Fuel Delivery Issue (i think)

[dvmotorsports]

So about two days ago I left my house going to work with the 40. Well after driving about 5 miles (maybe less), I started having what I believe fuel delivery issues.

What happens is between 10% and 20% throttle the motor wants to die. Before and after that throttle range everything is okay, but not great. I've had the carb rebuilt twice, fuel lines changed, fuel pump and filter replaced. I don't believe it is vaccuum related. If it was, I would think it would happen all the time. Once the vehicle cools off, it seems to be fine again when I start driving it. Then it repeats.

Any help is greatly appreciated. It is getting a new owner this week and I want to give them a vehicle that is mechanicaly sound.

 

[dvmotorsports]

Morning Update

So I got under the hood this morning and found that the banjo fitting on the fuel sending lines was loose and leaking a bit. Tightened it up and stoped the leak. Took it for a spin....No dice. Still doing it. I'm getting adequate spark too. I'm confused.

 

[Pin_Head]

It sounds more like a carb problem than fuel delivery. Fuel delivery problems tend to show up under high load sitations, like going up hill with wide open throttle. If it just bogs down temporarily during acceleration, it may be an accelerator pump issue with not squirting enough fuel. If it runs poorly as long as you hold the trottle at 10%, then it may be that the "off idle" or "transition slot" in the primary bore is plugged.

It could also be too much fuel. Lean mix tends to cause bucking and spitting if it is too lean to ignite. With too much fuel, the engine just bogs down or "loads up". This can be caused by the air vents, emulsion tube or "slow jet" being plugged or the power valve opening inappropriately (if you have one). What year are you talking about? If it does this while the truck is parked, then take the air cleaner off and take a peek as you open the throttle. If you see a stream of gas running out of the primary nozzle it might be running too rich at partial throttle.

 

[dvmotorsports]

Thank you Pin_Head. It is a 73. I hope it isn't the accelerator pump. I just had the carb rebuilt twice, pump included. I'm going down in the garage to check it out now.

****Could an extremely hot accelerator pump lead cause votage flux?***** I moved the wire and it seemed better. Time for a drive.

 

[Pin_Head]

****Could an extremely hot accelerator pump lead cause votage flux?***** I moved the wire and it seemed better. Time for a drive.

Only if the muffler bearing burned out your flux capacitor.
/jk

On a serious note, the accelerator pump is mechanical and is part of the carb. the wire going to the carb is the idle fuel shut off solenoid. If you paid to have it rebuilt, I would take it back and complain politely.

 

[dvmotorsports]

Hmmmm....

As I stated when I first joined, i don't know sh*t about carbs. What I find wierd is that when I spray brake cleaner into it, it bogs bad. I use to do that all the time to get it running......