Carburetor Question... 283 motor. (1 Viewer)

[ruining]

So, my '76 FJ40 has a 283 V8 conversion. I just picked it up recently and it's the first carb'ed vehicle I've owned and I know pretty much nothing about them.

The problem is, I will drive for about 10 - 15 minutes, and it'll just act like it's run out of gas. It has no other problems. It starts and runs fine, but after about that amount of time, or more if it's idling, it'll just die. I'll wait 3-5 minutes, and it starts right back up again.

Any ideas? It sounds like it's still squirting fuel and it doesn't smell like it's flooded. I thought it was because the alternator was dead and maybe the fuel pump was dying out, but after having the alternator rebuilt, I'm getting plenty of power, but still having the problem.

Any input is appreciated. Thanks!

 

[splib]

What carb does it have? Q-jet? Holley? Edelbrock? Model of the carb? Sounds like you have an electric fuel pump?

 

[ruining]

Sorry. Q-jet. Don't have the model number right now. It actually looks like a piece was taken off when it was sitting in a shop for a year. Looks like the owner robbed a part for one of his hot rods and "forgot" to put it back. I think I'm just going to take it in to have it rebuilt while I have all the electrical work done.

 

[cmiller114]

Sounds like vapor lock to me.....How is the fuel line routed?

 

[RMC73FJ40]

My son's did that and it was garbage in the fuel input side of the carb. It would run great until all the gas was used that was in the float bowl.

I've also seen it on a Corvette when the filter sock in the tank, on the output to the fuel pump, was dirty. The fuel pump would put suction on the fuel line and collapse the sock then the motor would run out of fuel. Once it was off the sock would expand and fill the fuel line. We drove about 100 miles.....a mile at a time.

I would also check your fuel pressure at the carb.

 

[ar2stp48]

Had the same problem with the fuel sock on pickup in tank once. Could tank vent be stopped up; try taking the filler cap off and running the engine.

 

[Pin_Head]

Start by taking off the air cleaner and watching what happens when it dies. Is there any fuel left in the carb when it dies (pump the throttle and look for fuel squirting)? Do you see fuel pouring out of the vent tubes into the throttle body? If there is no fuel, check for dirt in the tank, filter, lines, inlet check valve to carb. If there is fuel pouring out, replace the inlet check valve.

 

[Brian in Oregon]

I had so many fuel/carb problems on my pickup that I installed a small inline fuel gauge under the hood along with a clear fuel filter. This allowed me to diagnose what was happening. For example, I was seeing 5 psi at the gauge, but the filter was completely empty. Problem was vapor lock, but not at the carb. Found the fuel hard line was routed to within a half inch of the exhaust pipe, hidden just under the lip of the frame.

This proved to be such a useful diagnostic tool that I installed a similar setup in my FJ40. It came in handy diagnosing fuel starvation, which in this case turned out to be the new locking gas cap, which was not vented and caused a vacuum in the tank, which the fuel pump eventually could not overcome.

 

[ruining]

Thanks, guys. I'll be taking a closer look at it tomorrow.

It was running fine when it was parked, which was some time may of '07. It seems like it would be more likely to be crap in the lines than the way the fuel lines are run. I'll run it tomorrow and see if I can get anywhere with it.

 

[4x4Poet]

Try changing the little in carb fuel filter first. Run it, then change any inline filters. $6 total cost, so far.

 

[Downey]

1. Follow all above advice and ensure fuel lines are clear.
2. Vapor lock occurs between tank and pump. If an electric pump is mounted at the tank, good bye vapor lock possibility.
3. Save your gosh-darn nickles and dimes for a fuel injection conversion!!!