truck won't start
 

I have 61 GMC v6 305 that wont start. Last time started was about 3 months ago it back fired and didn't re start. I have replace the canister type fuel filter and the inline fuel filter also. Have used two different fuel pumps 9 O' Reily and Napa and still no go. Have disconnected the fuel line and gas gets to the fuel pump and not to the carb. Tomorrow i will prime the carb with gas and see. Please any suggestions. :helpsign:

Re: truck won't start
 

Acerna
Hopefully someone with more skill than I have will chime in soon, but Backfire can be several things. Usually its related to timing, but can also be a lean fuel condition as you suspect. I don't know which carb you have but putting an ounce of fuel into the air horn instead of dumping it down the venturi is a much safer approach and will give you a longer run time. That should be enough time get your fuel pump going.
These new fuel blends have a VERY limited shelf life so if it sat very long before you tried to start it 3 months ago you will probably have more work to do.
I have to pick up a grinder in San Antonio so If you need help or just want to chat I will pm you my number.
Oh and a fire extinguisher is a great tool to have nearby

Re: truck won't start
 

Greetings!

Since you are getting fuel to the fuel pump but not the carb, my suggestion is to check the inline filter installation. Inline filters are designed for the fuel to only flow through them one way. If the inline filter is installed the wrong way could be your problem.

Re: truck won't start
 

Agree with the others and agree with your efforts. Need to know if there is a filter between pump and carb. Need to know if you see no fuel coming out of pump output line when placed into a jar, while cranking for 15-25 sec, distributor center wire disconnected. If there is no fuel getting to carb, there is nothing to be gained by pouring gas down carb yet. You must do a proper pump flow test with no filters involved first.
I guess if you are curious if it will start/fire knowing no fuel is getting to carb, it's up to you. At least you will be happy if it starts/fires.
If no fuel at pump outlet (without filters)= bad pump, pump arm not aligned, air leak in hoses/lines, tank plugged, tank not vented. Not sure if all above will cause, just mentioning everything I can think of.
Should have a pretty strong pulsing squirt and start to fill jar pretty quick if battery and starter are up to snuff.
CAUTION: Fuel at the pump inlet can be deceiving. There will be a trickle or a dickle there but that does not mean the pump is getting enough fuel. Besides what George said, be sure there is gas in the tank, aye?

Re: truck won't start
 

Just to be sure the problem is fuel, take two minutes and put an old sparkplug on any plug wire, ground it and check for spark.
I have been fooled a few times over the years.
Good luck.