Engine Dies When Warm

[gulffishin]

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.

It ran fine up until about 5-6 months ago.

I give up ::throwing towel::

What do you guys think it could be?

Thanks for your help

[rickpilgrim]

If it were minr I would plumb a fuel psi gauge by the carb inlet and check the psi when it starts acting up.

[neto]

Check your fuel lines, make sure everything is tight and you don't have a pin hole somewhere especially if you have good fuel pressure. The other is maybe a vacuum leak? Automatic?

[gulffishin]

Thought I would post an update since I have tried a few other things to try and fix this.

I rebuilt the carb...again. This time I noticed a lot of fine yellow powder caking the inside of the carb...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!

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?

[geezer#99]

When it acts up do you look in the carb to see what's going on. Raw fuel means it's flooding. Edelbrocks are fuel pressure sensitive. 5 to 6 lbs max. You might have too much pressure or your float is set too high.

[68gmsee]

As Geezer said... Too much pressure can force fuel through the needle valve and cause flooding. Have someone look at the exhaust pipes to see if there's dark gray or blackish smoke coming out when its running.

re. filters: The filters should have filtered out any particles that would clog your carb that quickly. I had a real bad rust problem on mine and also used two filters. It would run fine for a few weeks until the filters got clogged up.

One other thing. Don't assume the fuel supply is sufficient just because there's pressure. If you don't have a fuel pressure gauge, unplug the line and insert into a plastic container. Remove the distributor wire to the coil. When you crank the engine you should see a strong pulsing stream of fuel and should get about a pint in 30 seconds or less.

[cdowns]

if using cheap rubber fuel hose it can be breaking down from the bad gas nowadays with the alcholol additives sendin gook to the carb or rubber lines can also b collapsing from suction and starving engine

are you positive your venting is good on the fuel tank?? have you tried removing gascap after the motor has run? a whooshing sound when removing gascap means bad vent

[gulffishin]

Whoa, thanks for all the replies, lets see if I can answer a few questions for you all and hopefully get this straightened out.

I have not checked the float level or checked the fuel pump with an empty bucket; I'll try that tomorrow.

I do not have an auto trans, pcv valve, or brake booster, just the old 3spd manual and manual brakes-the only vacuum hose I have connected is for the advance the rest of the ports are plugged.

I have checked for vacuum leaks by spraying carb cleaner around the mating surfaces, but have not noticed any difference.

I do have about 12" of cheap rubber hose coming from the hard line to the fuel cell and also going from the hard line to the fuel pump, but could they have degraded in 1yr? The vent hose is also just a piece of rubber hose 16" long or so tucked in the frame rail under the bed.

I did notice a yellowish pasty "goop" that dried to a white powder the last time I rebuilt the carb, but assumed it was dust or dirt being sucked in through the vent on the tank.

I drove it today and I stopped and looked in the carb to see what was going on when it started acting up. I wasn't sure what to look for, it didn't look out of the ordinary to me, but I couldn't see in to the fuel bowls very well and I could see gas in the fuel filters...if that means anything

I have not noticed a whooshing sound when taking the cap off, so I guess the venting is good...

Guess that's about it, thanks for all your help, if I find anything else out I'll post.

[gulffishin]

I just couldnt resist the temptation to go work on it again this evening and here's what I found:

The fuel pump is pumping good, but when I was looking at the gas it had pumped I noticed it was full of water!

The floats were also within spec.

So I drained the tank...again and took the carb off and it was full of this jelly like junk, so I cleaned it up, filled it with gas from a different gas station and will change the filters tomorrow and see what happens.

hopefully it was just some bad gas...