problem with fuel pump?

[71LT1-4SPD]

I took my vette for a ride today,weather was great.I notice that the enging started to idel rough when i stopped,it didn't stall,idel just dropped a little,the float in Holley carb is good not flooding,but i did notice that my gas filter was low on fuel (it's glass)and bubbling looked like air,checked rubber lines,no visible cracks,or leaks.I'm not sure if problem is fuel pump or maybe sock in gas tank is clogged,does anyone know how to check fuel pump.thanks i can use a little help.

 

[69autoXr]

If your fuel filter is a three-piece screw together, make sure it's tight, other wise, it sound like the lines are sucking air from somewhere else. Are the original steel fuel lines in place along the frame of the car? These could be rusted through in one small spot and allowing air to be drawn in. I had this problem on my 69, along with the fuel filter problem.

Chris

 

[MidShark]

I'm no fuel system expert, but here's my .02. The filter will not completely be filled with gas when running. That is normal. Not sure about "bubbling". You should get rid of the glass filter and rubber lines between the pump and carb for sure anyway- read the thread about the CAC member who just lost his car to a fire. You can check your fuel pump pressure with a guage, you can put it in-line to check it just before you switch over to the correct steel lines :gap Do you have the correct Holley carb on your car? Check those filters. Sounds more like a carb tuning issue than a fuel pump. Also, what about your plugs, wires, timing? Those could be a factor, too. Good luck!

Dick

 

[71LT1-4SPD]

THANKS for your replys.Yes I still have original steel lines from tank to pump.I have a new Holley 650DP on car.I just ordered a holley 780.I'm waiting for it to arrive.I checked glass filter to make sure it was tight,it was.When the engine was running the filter was always about 3/4 full.I'm going to check the pressure in pump,do you know what pressure should be from pump?69autoXr in your 69 where the rusted line was,did you get any sort of leakand how did you find rusted line?


thanks frank

 

[69autoXr]

The correct fuel pressure for a Holley carb is 6-7 psi. Holley recommends that you use a fuel pressure regulator with their carbs. My fuel lines were really bad, so I could see wetness on them near the leaks, and drips occasionally. I replaced the hard lines with braided hose and Aeroquip fittings. It still sounds to me as though air is getting sucked in, there shouldn't be any bubbles in your filter. Another possibility is that the fuel is getting too hot and boiling in the boiling in the filter. Does the fuel bubble when you first start the car or only after it's warmed up? This might tell you if it's air getting sucked in or if it's boiling. Are your fuel lines and filter very close to any heat sources? Make sure that your lines aren't touching any the lower radiator hose, and keep the filter away from the exhaust.

Chris

 

[71LT1-4SPD]

Thanks Chris,I'll check to see if there are any bubblkes when the engine is cold,I don't remember any thing touching the fuel lines but I'll check, just to be sore.I'll also find out about a fuel regulator.
Thanks ,Frank

 

[71LT1-4SPD]

Hey Chris,I think i found the problem,I went out and started car today,the gas filter was full when engine was running and no bubbles,i could feel the fuel pump pumping by sqeezing the rubber hose a little,but i realized that the steel line coming out of the fuel pump is resting on lower rad. hose.i have to get a new line and run it a different way.How is the line ran on your vette,does it run in front of the rad. hose or behind?
frank

 

[69autoXr]

My set up is not stock, I have an electric fuel pump at the back of the car with braided hoses carrying fuel to the regulator mounted on the inner fender well. My fuel lines never come close to any radiator hoses or other heat sources. You could try bending the steel line slighty to redirect it around the radiator hose rather than rest on top of it, and see if that fixes your problem. Then you could decide whether to replace the line or not.

Chris