Hey guys,

I am getting a new fuel pump cuz mine failed the volume test pretty badly. If i get a 8 psi pump now with everything else stock except the engine, do i need a regulator to lower the pressure for the stock carb? or is 8 psi ok. the pump doesnt need a regulator otherwise. Also if i fail the volume test for my pump will this keep my car from running more than 3-4 seconds?

Joshua

 

i think stock carb needs only 2-3psi, based on the flow needs of the stock carb. Do not run the stock carb at 8psi. The least that it will do is flood out your motor. the worst would be you would distroy seals.

 

Have you replaced the fuel filter recently? You car should idle longer than 4-5 seconds on the fuel in the float bowl alone.

 

Porting doesn't change the how the carb works, just like porting doesn't change the compression ratio. I makes the carb thirstier for more fuel since isit's sucking more air. It needs more fuel volume, not psi.

Simple answer, yes, it will need a regulator with 8 psi.

 

You may be alright at 8psi. I ran my carter pump without a regulator for some time. The restrictor in the return line will actually compensate for the pressure increase (somewhat). Best I can say is try it out, but long term you should get a regulator to "make it right".

 

Based on that last sentence, I doubt a pump replacement will solve your problem. Even a very weak pump will provide adequate fuel flow at low engine power settings. If your fuel filter hasn't been replaced in a while, do so and re-test. You might avoid mis-spending some money.

If you are convinced it's a fuel issue, check float levels and clean that little screen at the fuel inlet to the carb. Has the carb been disassembled and cleaned recently? Can you keep it running by playing with the choke?

 

Hmm, how will the regulator in the return line prevent 8 psi from going into the carb with too much pressure? I'm just wondering how that works.

 

If the pump is badly failing, there won't be enough flow to even keep it idling. Don't ask me how I know this. So the fuel pump replacement might well solve the problem.

Plus you're getting into things that would block the fuel flow in the carb, but he is saying the pump failed the volume test, which if done correctly it means the flow was tested before it gets into the carb.

 

The engine should idle longer than 4-5 seconds on the fuel in the float bowl alone even with no pump running, which is why I suggested checking the float levels also.

Fuel flow test by the FSM is done by popping the line at the carb, and measuring flow. This is obviously before the carb, but it's also after the fuel filter. A plugged filter will result in a poor flow measurement even if the pump is fine. Replacement of a $3 part and a bit more testing is needed IMO.