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cant keep truck running...

gulffishin

gulffishin

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I haven't posted in a while, but I am need of some professional help

I have a 64 with a 283, Edelbrock 600cfm performer carb and Edelbrock performer rpm intake and after I drive about 10 minutes it starts to run really weak-like it's starving for fuel. If I keep the throttle down it will keep running, but if I let off-like slowing down for a light, it will die. It will start back up easily, but if I don't stay on the throttle it will die almost instantly.

Funny thing is, if I start it in the driveway and hold the throttle open 1/2 way for 10 mins it will not act up. I have went about an hour before revving and idling and holding the throttle in the driveway and it never dies.

It started doing this about 5-6 months ago and since then I have rebuilt the carb, changed the plug wires, and put fresh gas in it, but it's still doing it.

When I rebuilt the carb, I noticed a lot of fine yellow powder caking the inside of the fuel bowls. I thought it could be sawdust or dust coming in through the vent line for the fuel tank. So, I drained the tank and blew compressed air through the lines and replaced the inline filter with 2 inline filters back to back, put fresh gas in it, and put a fuel filter on my vent line for my fuel cell.

Anyways, when i finished, it ran really good for about 30 mins, then it was back to the old stuttering and dieing routine. Exactly as before starts right up, runs a few mins then acts like its starving. If I blow air through the idle mixture screws it runs good again...temporarily.

I thought it may be the fuel pump, so I disconnected the fuel line from the carb (with the engine off) and it started squirting fuel from built up pressure, so I assume this means the pump is working and that the carb is clogged again!:mad::eek:

I also thought it may be bad gas, but I put the same gas in my car and other truck and do not have any trouble with those vehicles.

Any ideas? Should I just carry an air tank with me to blow air through the carb when it starts acting up?

I give up ::throwing towel::

What do you guys think it could be?

Thanks for your help
 
Have you checked for vacuum leaks? Do you have a brake booster?
 
I've sprayed carb cleaner around the mating surfaces and did not notice any difference in the idle speed.

No brake booster
 
are you running a pressure regulator? if so, is it adjusted correctly to around 6psi and do you have a bypass line back to the fuel tank so the pump can operate freely without being restricted?

It sounds like the carb is having issues receiving fuel at low demand, which I suspect could be either:

1. pressure regulator is set too low and the fuel filters are restricting fuel until the butterfly opens and the vacume helps pull fuel through the filters. (also could be simply too much restriction in the filters regardless of the 6psi being provided)

2. if you are not running a bypass line on the regulator the fuel pump might be dead headed due to the restriction at low RPM, resulting in dropped pressure at the carb when idling, open up the throttle and the pump is allowed to work...

good luck
 
thanks for your help leyland,

I do not have a pressure regulator or a bypass line back to the tank.

Everyone keeps saying in other forums I need a pressure regulator, so I guess I'll pick one up and see what happens.

My fuel pump only has one outlet, do I need to replace it with another pump with two outlets to send gas back to the tank?
 
on second thought have you considered ignition instead of vacume?

what type of distributor are you running and where are you drawing vaccume advance from? I wonder if its an ignition issue, possibly the springs or weights hanging (maybe something broke inside the distributor) or a vacume line collapsing and failing to provide vaccume to the distributor.
 
I could be wrong (never done this myself) but I understand you can buy a regulator with (or without) a bypass line fitting... get one with a bypass option. have a look at jegs or other online supplier.

were you using this set up for long before you noticed the issues or is this a result of new upgrades a few month's back when issues started?
 
LEYLAND said:
on second thought have you considered ignition instead of vacume?

what type of distributor are you running and where are you drawing vaccume advance from? I wonder if its an ignition issue, possibly the springs or weights hanging (maybe something broke inside the distributor) or a vacume line collapsing and failing to provide vaccume to the distributor.
Click to expand...

It's a cheap hei unit that was on the truck when I got it. I have the vacuum hose connected to the left side of the carb...ported side I think.
 
LEYLAND said:
I could be wrong (never done this myself) but I understand you can buy a regulator with (or without) a bypass line fitting... get one with a bypass option. have a look at jegs or other online supplier.

were you using this set up for long before you noticed the issues or is this a result of new upgrades a few month's back when issues started?
Click to expand...

I noticed it a month or so after the new upgrades. Seems like the carb is getting a lot of junk in it. Every time I take it off it has this jelly like stuff in it. I thought it might be the vent hose pulling some junk in.
 
I think maybe just guessing here only because I had a friend with a pantera that had the same problem, it turned out that he had gotten silicone in his gas tank, not sure if the previous owner had done this or had gotten this contamination at the local gas station, you say you have a fuel cell in your truck, did the previous owner seal the fittings with silicone....?
 
If you had a fuel pressure problem that required a regulator then you would be flooding over not starving for fuel. Pressure regulators don't increase pressure they just keep it regulated. AFB carbs don't need more than 5 1/2 PSI fuel pressure. I run 5 PSI with 2x4's on my 61 and it runs fine. If you have a stock pump you should be fine without the regulator. The starving problem still sounds like you might have a plugged vent or possibly a collapsed fuel line. Have you tried just leaving the gas cap off or blowing a little compressed air in to the gas tank to push fuel up to the carb? It also sounds like you may need to take your tank out and wash it out to get what ever is in it out of it Good luck....Big Tim :cool:
 
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Are your fuel lines new? I've had the inside of a rubber fuel line peel back inside from being taken on and off too many times blocking flow. Is your jetting correct? I have had the amber flakes in the bowls before, little bits of varnish from evaporated fuel. They can dissolve sometimes, could take a while. I have had silicone in the tank before, i's a pain. Had to blow out the filter almost daily for too long. Might be easiest to flush the tank.
 
Back from the dead...

I sold my truck a while back and have the itch to get another one, so I am looking over my past posts just for fun.;) I also thought I would post the final verdict with my fuel situation since I am already here.

I looked down in my fuel cell, and it was full of crap and had water in it! I'm not sure where it came from, but it's probably from from junk that used to collect around the opening and likely fell in during fill ups.

Anyways, I drained the fuel cell and let it dry without the cap on it. Then I took a rag and wiped as much of the junk out of it as I could. Then I blew out the lines with the air compressor, replaced the rubber lines, rebuilt the carb..again, replaced the fuel pump and fuel filter, and filled it up with fresh 93 octane.

Ran great after that. :D
 
I have been looking all along, but haven't found "the one" yet. I am looking for either an AD or a 63-66 with a factory AC cab. Pretty slim pickins where I am and the prices can be really outrageous....people using the "bluebook" value:rolleyes:

I am also trying to be a little more picky with looking it over real well before I buy it. My last truck was an impulse buy, and I should have paid more attention when I was inspecting it.
 
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