The saga continues - Sputtering, loss of power when accelerating
 

Driving along this morning and everything was fine. All of a sudden it starts sputtering when I accelerate and I'm not getting enough power.

It's had all new plugs, points, tuning etc.....

However, I've put an inline fuel filter before the carb and that has some crap in it. Not a huge amount (I once owned a straight 6 Fairmont that would run like a champ right up until the filter was chock full), so I wouldn't have thought that would be the cause?

Naturally this has happened the day I decide to take it to work. So now I'm here all day being paranoid that I'm going to cause damage trying to nurse it home. Or that it's not going to make it.
Oh, it's a 61 305D if that's relevant at all. And yes, it has petrol (although at the moment I am having to use a broom handle to determine that).

Re: The saga continues - Sputtering, loss of power when accelerating
 

There's a hidden filter under the passenger side cab. It looks like a soda can sticking down. The replacement part is Wix 33271. Swap that puppy out and see if it clears up. Oh, and gas runs ALL DOWN your arm when you unscrew that can. :teehee:

Re: The saga continues - Sputtering, loss of power when accelerating
 

Is it re-useable? I guess what I'm wondering is if I take it off and give it a fling out (hopefully removing the crap that's in it, if that's the problem) will I be able to just pop it back in?

This is just so I can get it home of course. I'd be getting a replacement first chance I get.

Also, when you say the gas runs down you're arm, does that mean it's going to just keep spewing out of the tank until I put it back in? Or is it just going to be whatever amount of gas that's currently sitting in the filter?

Fingers crossed it's something this simple. I'd be pretty devastated if it was something catastrophic.

Re: The saga continues - Sputtering, loss of power when accelerating
 

Just went through this. Ended up being that the sending unit did not have the screen on it allowing a ton of crap through the line and into the primary filter. And with an electric pump you know something is wrong Right away. New sending unit, 2 new filters, blew out the lines and for the 1st time I am actually seeing 10 psi cold.

Re: The saga continues - Sputtering, loss of power when accelerating
 

That all sounds much better than what my worst case scenario brain was thinking. Typical of me, my first thought was a dying engine.

I'm really hoping it's something basic..... There is some crap in the pre-carb filter, and pretty much the only mod-con that the truck has (other than seatbelts) is an electric fuel pump.

I've already got a new sending unit on order (as much as I don't mind checking the level with a stick, it's not something I want to keep doing).

So, fingers crossed? Is there a chance it could be something major? If so, what other symptoms should I be looking for?

Re: The saga continues - Sputtering, loss of power when accelerating
 

If your driving along and it just suddenly starts to spit and sputter is normally two things...fuel or ignition. In this case all your ignition components are new so there's a 99.99% chance they are fine. The fuel system however I don't recall you checking? If some crap got to the second filter I am sure the 1st is packed. That's how it was with mine. By the way, be sure to disconnect the metal line from the send unit at the tank...that helps keep the fuel from siphoning and emptying the tank when you pull a line off from underneath. lol

Re: The saga continues - Sputtering, loss of power when accelerating
 

I had an old Fairmont before with a badly rusted fuel tank. Consequently, I had to carry a tank of compressed air in the back seat so that when the sock in the tank filled with rust I could pull the line off the pump and blow air back through the fuel system (which blew the rust off the sock) and then suck petrol back up the line, reattach it to the fuel pump and keep going.

For the short term (IE getting me home today) could I do something similar as a test? I don't have a tank of compressed air, but I'm thinking if I blow into the fuel line really hard I might be able to lung it? Except I'm assuming since this is an electric fuel pump I won't have to suck petrol back up the line afterwards?

Also, there's a shutoff valve on the petrol tank. Presumably if I close it then that should keep the tank from emptying when I pull a line off?

I know some of these are going to be 'duh' questions, I'm just well aware of my own limitations when it comes to experience and whatnot, so I'd rather ask a dumb question than assume that I know what I'm talking about and make a dumb mistake.

Re: The saga continues - Sputtering, loss of power when accelerating
 

You won't be able to blow hard enough. haha I'd just cruise it home and on the weekend take the time to fix it, so that way you can Find the possible problem and know you've fixed it. When mine had issues it happened at the worst possible time...leading me to think it was one of a million issues. When my engine lost power I was pulling a hill at 57 mph on a 105 degree day. Lost power and thought it had eaten rings. Looked through the mirrors for smoke and saw nothing...next thought was ignition or fuel...limped to the top and pulled over. Idled perfect....took a non load throttle fine....but you could grab the filter and feel the fuel pulsing really bad. I thought it was boiling, but it was really pulsing because of the clogged filter BEHIND the pump. That's the issue...Pumps are made to Pump...not Pull. The pump was having such a hard time Pulling that it couldn't keep up with the needs of the motor at speeds above 45 or under hard acceleration. Thus making me think things were worse than they were. So I decided to redo the Whole system starting with filters....and there it was...a jam packed filter behind the pump. Lucky I didn't fry the pump. I them completely removed the sending unit from the tank and saw there was no pickup screen....replaced it with a new one I had already(:upyes:) and cleaned out the lines. Went ahead and installed a USA made pump in with two fresh filters one in behind and one in front of the carb for more cheap insurance. And am now running at 10 PSI cold and 6 PSI hot and happy. I need to regulate it down to 5 as eddys hate high pressure but no issues yet.

Unless you have all the tools you need, I'd limp home and wait until the weekend to do any work.

Re: The saga continues - Sputtering, loss of power when accelerating
 

Hello All,
Quick one as I'm on a phone. I nursed him home!

Fingers crossed this weekend is a productive one lol

Re: The saga continues - Sputtering, loss of power when accelerating
 

My 64 suburban did not have a filter between the tank and the fuel pump, so all the crap filled up the fuel pump. took the pump a part cleaned it out. put a filter on the tank side of the pump. In the end, I took off the fuel tank, pressure washed the inside,used muratic acid to clean, lined it with red coat. Tanks that are real bad throw a chunk of chain in it and shake it. The best redneck way is to fill with some gravel, strap it to a tractor tire, and go for a drive.

Re: The saga continues - Sputtering, loss of power when accelerating
 

So, I've finally had a chance to crawl underneath it (we've been moving..... No doubt it would've gone faster had the truck not been out of action) and there doesn't appear to be another inline filter anywhere between the tank and the one that's just before the carb.

There is an electric fuel pump. So, do we think there's any harm in disconnecting the battery and having a tinker to see if there's any scrud in the pump itself?

The only reason I ask is I've only ever done this kind of thing on a mechanical pump. Not sure if there's anything special I need to consider with an electric one (and the Google isn't helping much, because most of what I'm finding relates to fuel injectors etc....)

Re: The saga continues - Sputtering, loss of power when accelerating
 

Disconnect the battery and jerk that ol pump out. Be sure to disconnect the line from the sending unit. Look into the ports and see if there is any crap. If there Isn't then check all the lines. Pull the sending unit out and check it, make sure there is a screen at the end. Also look into the tank while there. Then remove the line from the carb and pull the filter and blow compressed air through that line into a jug at the other end to see if any crap comes out. If so...there's your problem and check that filter as well. If there Isn't any crap in the line...replace the pump, filters, and all old rubber line. I'd do a double filter system with a filter behind and in front of the pump. Super cheap insurance and can save the pump. Saved mine, but I went with a new one anyway. Good pump if you end up needing one would be a Carter 50 GPH. Puts out around 4.5 to 8 PSI. USA made.

Re: The saga continues - Sputtering, loss of power when accelerating
 

I had the exact same symptoms one time. After a lot of checking things and head scratching, it turned out to be a glob of silicone sealant some previous owner had glommed onto the bottom of the pickup tube inside the gas tank. During normal driving it would run fine, but flooring the pedal sucked up enough gas that it would pull up the silicone glob (like a hinge) and block the tube.

Re: The saga continues - Sputtering, loss of power when accelerating
 

It's definitely looking like a sediment issue in the tank/lines. I took the fuel pump off (or, mostly off as I left it wired up) and blew some air through it (sadly, I don't have an air compressor, so when I say I "blew some air through it" I'm being quite literal) and what came out the other end was full of scrud.

After hooking it all back up, I was able to get a nice sounding rev out of the engine again. I've not taken it for a test drive yet, but I'm somewhat optimistic. I still don't think it's getting as much fuel as what it should, as the inline filter before the carb isn't as full as what I would like. But, at least it's a start.

Either way, I'm thinking it's going to need the thank cleaned (or replaced). I'm not keen on having this issue crop up every couple of months/weeks.

Re: The saga continues - Sputtering, loss of power when accelerating
 

A full system flush at the very Least is in order. Pull the sending unit and look into the tank to see how bad it really is. If it's really bad Classic Parts can get a tank to you for a good cost. I'd also invest in a new sending unit, electric fuel pump, and two filters. One before and after the pump.

Re: The saga continues - Sputtering, loss of power when accelerating
 

Supposedly it's a "new" tank and a "new" fuel pump. The latter might be true, but I'm seriously doubting the former. Particularly if there's that much scrud going on?

The good news is I had already ordered (and have just received) a new sending unit, as the gauge hasn't worked from the start. All the wiring and whatnot checks out as far as that's concerned, so hopefully there's going to be a bit of killing 2 birds with 1 stone.

I don't plan on installing the sending unit though until the issue with the tank is sorted. Otherwise, knowing my luck I'll have to get yet another replacement far too soon.

Re: The saga continues - Sputtering, loss of power when accelerating
 

If it isn't to bad you can always pull the tank and flush it. Then recheck. Main concern is loose rust from years water in the gas and condensation eating at the metal and gas itself. Had a tank that looked great, but after a hard flushing leaked like crazy. New tank was on the way and installed 6 days later. lol

Re: The saga continues - Sputtering, loss of power when accelerating
 

I'm a bit jealous as to how easy it is for folks in the States to get parts. It's a bit more of a time consuming/costly affair over here LOL

Re: The saga continues - Sputtering, loss of power when accelerating
 

My bad, I thought you were in the states for some reason. haha

Re: The saga continues - Sputtering, loss of power when accelerating
 

It was a pretty safe assumption.... There aren't exactly a slew of GMC trucks down under.

Re: The saga continues - Sputtering, loss of power when accelerating
 

So, apparently the plugs had fouled and the points needed adjusting. While there is a bit of sediment in the fuel, I'm told the tank is actually pretty clean.

Am I being unfair in thinking that if it was tuned less than 2 months ago and it hasn't been pushed real hard at all since then that I shouldn't be getting plugs which are fouling prematurely? I like the guy that's done most of the work. But, my gut is starting to tell me that maybe I'm getting taken for a ride. This last trip to the shop resulted in 11 hours of labour for the following:

Oil change (it was only changed 6 weeks ago. But, it had gotten dark pretty quickly)
Valve clearance adjustment
disassembly of distributor, clean and adjust points, lubricate advance weights
replace fuel sending unit
rework delivery pipe (the sending unit didn't quite align)
install a headlamp relay

I'm happy to pay what a job is worth, so if y'all think 11 hours is fair enough then I'll chalk it up as a lesson learned (IE, stop putting off buying the tools and shop manuals).

This dude is telling me that if it was him he would look at doing an engine rebuild in the next 6-12 months, as the engine is getting a bit noisy..... Again, it's all just starting to sound a bit over the top to me.

Anyway, the good news is I should be on the road again tomorrow.

Re: The saga continues - Sputtering, loss of power when accelerating
 

11 hours? Really? This guy work on tonkas for a living or what? lol Rebuild the engine cause it's noisy huh....hmm...I guess he's never head of solid lifter cams. He did set the adjustment to .012 intake and .018 exhaust right?

Re: The saga continues - Sputtering, loss of power when accelerating
 

If it took him 11 hours to do all that he was working in the dark after killing a keg. No way! :pullinghairout:


First rule of 6066 GMC Club - Don't talk about 6066 GMC Club! Ok, that's not really it, but the first rule should be "Don't let anyone work on your truck but YOU."

Too many times we've seen great iron be mistreated by ignorant (though sometimes well meaning) mechanics that have zero experience with a car that doesn't run on a computer.

If you're going to run an old truck you *NEED* to buy a manual and you need to be willing to get your hands dirty. It's just a necessity, but it's a good one. You'll learn valuable skills while tinkering with your baby and you'll grow closer to the historical genius engineering that made these engines. There's nothing like them, even today.

You don't need a ton of tools either. You can do most work on these trucks with a standard socket set (not metric), a couple of screwdrivers, and a set of wrenches, again standard. So for $60.00 you're all set to start fiddling!

The point is that you can't trust anyone with your truck. Only you. :thumbsup:

Re: The saga continues - Sputtering, loss of power when accelerating
 

I certainly agree for the most part that I want to get to a point where I'm doing the majority of the work. But, at the end up the day facts are facts. If the vehicle is getting work done in a garage that specializes in vintage cars then I'm going to feel more confident about the outcome than what I would if I was to attempt to do it myself. Particularly when you consider the fact that at the moment I've got a socket set and pretty much nothing else.

At the end of the day, I'm just not the type of person who is going to feel like I'm somehow less of a guy simply because I'm willing to defer to someone that knows more about something than what I do. In fact, that's half the reason why I don't have a problem asking what's possibly seen as stupid questions in this forum. This is all a process that I've only just started. Personally, I think things like comes across like the type of know it all bragging that I just don't think helps anyone. For example, even I know that there are a lot of reasons why an engine might be making more noise than it should. It seems pretty reasonable to think that a vehicle that is close to 60 years old might have a bit of piston slap going on.

If that's the case, why not look at doing a full rebuild? If the idea is for it to be the best than it can be and you've already committed to having the engine out, wouldn't it make sense to do it all while you're at it? I think so, others might not but that's ok.

Anyway, I guess my point (as this has gone off topic a bit) is that if my dog has a scratch, I'll take care of it myself. But, it's got a broken leg, I'm going to take it to a vet. Same idea. I'll do the work that I'm comfortable and capable of doing, and I hope with time that covers more than it does at the moment. But in the meantime, I'm not going to get my feelings hurt simply because a mechanic or an auto electrician or whoever knows more about this than what I do. That's why they're getting paid to fix cars and I'm getting paid to do what I'm doing. That's also why I come here, because there's loads of people that know more about this.

Re: The saga continues - Sputtering, loss of power when accelerating
 

On one hand you asked if you should buy a manual and learn. Then you turn around and say you're "not less of a man" for not doing the work yourself...I don't get where you think we're saying you have to "be a man" and growl at it while you eat a raw turkey leg.

What we're saying is your mechanic is stealing your money and you should'nt have your entire engine rebuilt just because his rent bill is due. It's up to you, dude. It's your truck and it's your money. Just don't ask if you don't want an answer. I don't have anything else to say on the subject.


:goodluck:

Re: The saga continues - Sputtering, loss of power when accelerating
 

Truth be told, I think the lesson here is I shouldn't communicate with the outside world when I'm at work. LOL I'm never the best version of myself when I'm in this place.

No offense was meant. I've just gotten prickly about it for no good reason.

Thanks again

Re: The saga continues - Sputtering, loss of power when accelerating
 

It's tough to read intent or emotion on these forums sometimes.

But having read a lot of posts from TJ and Fletch; I find them both to be pretty funny (Fletch) and resourceful guys (TJ-LOL-tongue-in-cheek), in their own unique ways. I've never met them so I can only go by what I read and my gut feel about them which is; very Positive and always helpful.

I detect some contradictions in your posts and nowhere did I read that someone questioned your manhood.

In my opinion:
The question/concern put forth by you was answered in a "tone" that I've always picked up from TJ and Fletch. You mentioned some terms like piston slap which tells me you know something more then a guy that just has a crescent wrench set.
That's probably why you came here to get confirmation and I think you got it.

Does not doing any work on your car/truck make you less of a man? Of course the answer is NO, but it helps to have the manual and read up on the areas you are having worked on, so you could ask the mechanic about the valve adjustment specs etc...etc.

It's great that you'll have your truck back on the road but...

I would trust your gut on this; but not with the raw turkey leg. but I digest...I mean I digress LOL

Re: The saga continues - Sputtering, loss of power when accelerating
 

My post was taken completely wrong. lol Sometimes it's hard to tell a person's attitude through a key board.
The 1st red flag for me was it took 11 hours to do basically an engine service and some other minor work. I service my 305 in about an hour. So, 10 more to do some other stuff.......hmm....

2nd red flag, Why did he do All that work just to tell you it's gonna need a rebuild in 6 months? Unless your driving the truck EVERY day, 6 months worth of miles is really not that much. I drive mine 7 days a week so the miles add up quickly.

Also, there are Plenty Vintage Car Guys/Garages that have never even Seen a GMC V6. I've seen plenty on Youtube that always say, "First time I've seen one!" That's why I said...He probably has never heard of a solid lifter cam because these engines are Supposed to have valve tapping noise(Assuming that's the noise he's referring to, which I should have mentioned.) That's one easy way you know the valves aren't to tight. lol Thing is, the valve train is noisy enough that sometimes you may not even Hear a slight knock in the motor. Mine had a slight throw out bearing knock only hearable from inside the cab, in the bay you could only hear loose and happy rocker arms.

I understand your irritations. And know that none of us are Downing you in any way because you are trying to do your truck the right way even if it means having someone else do it. We just don't want to see you get ripped off. It's an unfortunate thing that a lot of shops do it now a days.

Re: The saga continues - Sputtering, loss of power when accelerating
 

Just a thought, and my 2-cents...
Oftentimes when a problem pops up, it is very likely that the most recent change to hardware or other maintenance makes the problem appear in the first place, so going back to what was last done may be the issue.
You mentioned you are using an electric fuel pump- is this recent? Do you have a fuel pressure gauge (gauge AND regulator is better) to actually see what the fuel pressure in the line actually is? Fuel delivery pressure is important, and not all electric fuel pumps are created equally- some are quite poor in their basic job of a steady pressure and fuel delivery.
Has your mechanical fuel pump been removed from the engine, or is it still in place? If still in place, is your fuel line still connected inline or has it been bypassed?
Do you currently have a fuel filter on the pickup tube in the tank? You mention some "stuff" in the carb pre-filter- it's coming from somewhere upstream, most likely the tank.
If the innards of your tank is at issue (most 50 year old tanks should probably be replaced), then I would suggest this as a thought to pursue. Check out http://www.tanksinc.com/index.cfm/pa...rod/prd404.htm

Anyone out there who has "dressed up" their fuel delivery lines with the fancy (and $10.00 a foot expensive) should think really hard about removing it and hard-plumb it. It is nothing more than cheap rubber hose made in China that is covered in the braided stainless, and is not even compatible with gasoline for long periods, and I am a testament to this fact... I was backing my 55 Chevy out of the garage recently, and smelled raw gas- found a huge puddle under the engine, and it was soaked. Fancy SS covered fuel line has split. Can you say FIRE? Well, there wasn't one, but there easily could have been. :ahhhh:
Not to worry- :yes: NAPA has some hard line that is very malleable, because it contains some copper, it is easily bent, lasts forever, and is nice to look at with a very subdued gold look to it.
RUBBER FUEL LINE is just fine to use, just not the junk that is masked with the braided stainless mesh, at least the stuff that I had under my hood at the time. It just needs to be stamped as "fuel line", because that is what it is made for.

Re: The saga continues - Sputtering, loss of power when accelerating
 

Before spending any more money at the shop, I would have a compression test done. You really shouldn't have to change the oil after 6 months unless you've put some serious miles on the road. I surmise that you have some bad piston rings. This could be the culprit for the dark oil and fouled plugs. If you have bad compression, then you are up for a rebuild. If that is the case, you will now have a big decision to make. You will need to decide whether you are "all in" on the 305 or go another route such as swapping it out with a SBC for example. Getting the 305 rebuilt is going to be quite the challenge: both finding parts and finding someone you can trust to do it. Rebuild parts are extremely hard to find, and if your crank, cam, and/or pistons are shot, the task is even harder. I don't think anyone makes cranks, cams or main crank bearings anymore, so you will be looking to find NOS. Rebuilding the 305 will probably be much more money than swapping a SBC. But, I assume you are here at this 6066 forum because you believe there is something really cool about the GMC big block V6's. That is why we all are here!!! Finding a used 305 is also a recommendation.

Now if your compression is okay, I would replace the entire fuel system. Everything. Until the bad gas and sludge is completely removed from the entire system, you will never solve the problems.

If you are still fouling plugs, you can move on to the carb, timing and distributor.

This process should narrow down your issues. And, I agree with everyone, that 11 hours is way too much to spend before determining if the engine compression is good enough to begin with. It could be that the mechanic spent 7 hours of the 11 reading up on the GMC manual on how to fix things.

I hope this helps!

Re: The saga continues - Sputtering, loss of power when accelerating
 

Don't even bring up the thought of replacing the V6 with a SBC 350:pullinghairout:. If the 305 will be too costly to rebuild there is always an alternative to find a good used one and even upgrade to a larger V6:thumbsup:

Re: The saga continues - Sputtering, loss of power when accelerating
 

I totally agree! But, realistically, there probably aren't too many used GMC big blocks laying around in junkyards in Australia.

Re: The saga continues - Sputtering, loss of power when accelerating
 

Rebuild parts for a 305 V6 really Aren't That hard to find either. I got most of the parts from O'riellys. Didn't do rings, but gaskets, rod bearings, oil pump, timing set, and casting plugs all from auto parts stores. The rings I believe are still available to and the main bearings have to be purchased NOS. Valves I think may be available through Ebay and Summit Racing. Heck, might even be available from Napa. Cam bearings unsure of as well. Parts are there, but not quite EXTREMELY hard to find. Least not a good enough reason to put a 350 in there. lol

Re: The saga continues - Sputtering, loss of power when accelerating
 

Not a chance I'm going to put 350 in.... I just couldn't see myself parting with what's in there. I guess worst case scenario would be somewhere down the line finding another 305D to replace the current one. But, that's (hopefully) a long way off yet.
Now that it's home I'm going to try to go back to driving it daily, just enjoying the old guy. However, I'm also going to do a compression test.... At least then I'll have some idea as to the general health of the engine.
I think I've finally accepted that I would rather spend the time and money on tools and learning than get someone else to do the work. I guess I just thought getting an 'expert' to do the work initially was better for the truck.

Is it worth posting a video so y'all can hear how it sounds?

Re: The saga continues - Sputtering, loss of power when accelerating
 

I've uploaded a small video.... Sorry in advance for the file size. But, does it sound ok?
The carb has been leaned out a bit, so that's why (I think) it played up briefly (I didn't have the choke out at all because prior to today it was too rich. Also, it's like a sauna weather-wise over here)
https://1drv.ms/v/s!AjwPdb4c9NJus3o3lgBeTLTkLiGL

Re: The saga continues - Sputtering, loss of power when accelerating
 

Sound good to me.

Re: The saga continues - Sputtering, loss of power when accelerating
 

Sounds pretty smooth to me. Nice truck too!

Re: The saga continues - Sputtering, loss of power when accelerating
 

Thanks for listening and whanot! I've been worried it's sounding more ticky than it should.

Re: The saga continues - Sputtering, loss of power when accelerating
 

My computer didn't wanna load the file so I couldn't hear. :( Sure it runs like a top though. :thumbsup:

Re: The saga continues - Sputtering, loss of power when accelerating
 

Regarding your post on the 27th. The points should last more than 2 months. Mine were burning up and leaving me stranded--then I checked voltage from the key to the coil. 12 volts.

Not good, and was destroying the points in about 3 months of daily driving (back when I had hair--- see my build journal). GM built these trucks with a "fusible link" -their term for a high resistance wire- that dropped the voltage to 6 entering the coil. The PO had replaced the wire, allowing 12 volts to the coil.

Chrysler (and others) use a ceramic resistor to drop the voltage. I used one I had on hand, and my points were not a problem again. Sure, they need to be checked, but they are pretty low maintenance.