fuel pump question.

Started by Dave, April 03, 2004, 07:18:26 AM

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Dave

ive got a new mechanical carter fuel pump on the 350 chevy in the 32. Im fighting some wierd idle issues and ive had the edelbrock 600 off twice. Heres the question Shouldnt the fuel line have some fuel in it? Ive even replaced the filter and its a foot from the carb inlet after the pump and still no fuel. Im trying to figure out why the idle acts wierd. I can only get one idle mixture screw to work right and when I do get it adjusted it will idle ok and then it just kinda hiccups and goes back to a fairly good idle again. It runs like a raped ape when i hammer it. ANd no theres no vaccum leaks ive already checked for that.
Dave
:?:

Bruce Dorsi

If you can temporarily install a fuel pressure gauge, you may get some insight into what is happening.

One possibility is that a check valve in the pump is not sealing completely, or hanging open, allowing pressure/volume to be erratic.

At higher speeds, the flow rates are much greater, so a small leakage will not affect pump performance as greatly as at idle.

The pump should not affect why only one idle screw has any effect, though.
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If being smart means knowing what I am dumb at,  I must be a genius!

GPster

Just to post some ideas from my large bag of mis-information. Is the vent open on the tank? If you're pumping a vaccuum on the tank it may be overworking the valves in the fuel pump and letting it siphon the gas back. You haven't put sealer in the tank recently have you? I have had the sealer not set up properly in a tank before (when doing it in the basement in the winter) and it seemed to coagulate in strange places and it even got through the filter. It looks like a very fluid clear silicone and I had it plug off the idle circuils in a Carter carb one time. GPster

Dave

Quote from: "Bruce Dorsi"If you can temporarily install a fuel pressure gauge, you may get some insight into what is happening.

One possibility is that a check valve in the pump is not sealing completely, or hanging open, allowing pressure/volume to be erratic.

At higher speeds, the flow rates are much greater, so a small leakage will not affect pump performance as greatly as at idle.

The pump should not affect why only one idle screw has any effect, though.

Thats what im thinking. I went to the store today and bought a vaccum gauge too bad the first store didnt have it for 8 bucks cheaper  :cry:
Then is reset the idle. Its better but it still gets the hiccup and im thinking its a pump problem at idle. It will idle along fine untill it decides it doesnt want to LOL. Took it out for a test cause I was working on the kick down cable and it gets up and goes. Im sure the pump is flakey cause there should be some fuel in the line. Id buy a new pump before id play with a pressure gauge just cause it doesnt check the fuel. And the tank vent is fine.
Dave