Fuel Delivery Issues?

[Cdubya27]

So my '78 C-10 suddenly won't start. The motor turns and turns and turns, but doesn't seem to get fuel. Now, if I dump a little gas in the carb, it'll start right up and keep on going until I shut it off, and then I can even start 'er up again, over and over. BUT, after sitting over night...it won't start again...just turns and turns.

Some specs:

• 1978 C10
• Rebuilt 97 VORTEC 350
• Carburetor - not fuel injected
• Electronic Fuel pump

Thoughts?

 

[1987 GMC Jimmy]

Have you listened for your fuel pump or pulled the line to check for fuel while it’s turning over? How is it wired? Is it an external type pump just wired to a 12V ignition source, or is it an in-tank, regulated, and relayed type pump? You gotta see if the pump’s giving you fuel first. What about your carb? Has it sat for a while, or has it been a long time since it was rebuilt?

 

[4WDKC]

my guess is floats stuck?

 

[Cdubya27]

First off, thanks for the replies...its really appreciated!

@1987 GMC Jimmy The fuel pump is external mounted next to the fuel tank but easy to get to. I haven't pulled a line to see if it is pumping while turning over...I can do that next. I don't have any idea about the Carb. I've only had the truck for a few months, and I don't have any idea how old it is or whether its been rebuilt.

I guess the most confusing part is...why will it KEEP running once it gets started with a bit of fuel dumped in the carb? Is that 'priming' something that then allows for gas to get delivered? If the fuel pump were bad, wouldn't the motor just die after it consumes that little bit of fuel in the carb?

@4WDKC - talk to me about the float being stuck... will that prevent gas from flowing until the motor got 'primed' with that little bit of gas in the carb? Also to note...my gas gauge doesn't work...when you turn on the truck, the gauge goes from empty, all the way past the full mark to the far right. I've checked the ground wire and reset it and it seems to be ok but didn't make a difference. So could the float be the culprit?

 

[4WDKC]

I know very little about carbs but as I understand it, the float controls when fuel is allowed in the carb. When it's high no fuel enters, when low it floods. Could be vibration frees it, also could be lack of power to fuel pump like someone mentioned.

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[yevgenievich]

Choke working?

 

[Cdubya27]

@yevgenievich - that's a good thought...I do believe the choke is sticky as it really had a hard time in cold weather until it would warm up...perhaps its the culprit.

 

[yevgenievich]

Relatively easy to verify. Guessing it is electric choke? See what it is doing with air cleaner off. Good way to verify fuel is in the carb is to move your throttle linkage manually while looking down the carburetor. It should pump some fuel in on every rotation of the throttle

 

[Cdubya27]

@yevgenievich - Well I believe you hit the answer on the head. I pulled the Air Cleaner and the Choke (electric) doesn't even have a power connector attached...just the ground. I manually shut the Choke and it started up with relative ease.

I don't see a loose power connector anywhere, So my next step is to get a power cable to that lead. I understand it is supposed to be a 12v connection and I guess I just run it to the fuse box and tie into an Ignition slot?

I do wonder why it has started fine for the past 6 months and just now is having issues. If the choke hasn't worked since I bought it, I would have thought that would have been an issue from the very beginning.

Anyway...thank you ALL for your help. It's great to be a part of a community like this!

 

[yevgenievich]

choke is usually powered from ignition hot 12v.

 

[4WDKC]

@yevgenievich - Well I believe you hit the answer on the head. I pulled the Air Cleaner and the Choke (electric) doesn't even have a power connector attached...just the ground. I manually shut the Choke and it started up with relative ease.

I don't see a loose power connector anywhere, So my next step is to get a power cable to that lead. I understand it is supposed to be a 12v connection and I guess I just run it to the fuse box and tie into an Ignition slot?

I do wonder why it has started fine for the past 6 months and just now is having issues. If the choke hasn't worked since I bought it, I would have thought that would have been an issue from the very beginning.

Anyway...thank you ALL for your help. It's great to be a part of a community like this!

zip tie holding it in place finally broke? It migh tbe disconnected because it wasnt working, may want to check resistance to confirm its good, if not replace it.