The engine is a 355 carbed engine in a 87 Camaro which did have a mechanical pump on it. I put in a Carter p4594 electric fuel pump (https://www.jegs.com/i/Carter/180/P4...B&gclsrc=aw.ds) and connected the pump to the tank and the existing fuel line and at the engine I by passed the mechanical fuel pump. and connected directly to the carb. I still have the mechanical on the engine disconnected from the tank and I closed off its return line back to the tank. The electric fuel pump is connect to a fuse in the fuse box with a jumper. This car still has the computer in it from when it had a fuel injected 305 in it. The pump stays on all the time , and it runs like hell.
So could this be a computer thing or should their be a pressure switch turning the pump on and off. It says 12lb pressure at the carb , the mechanical was 4 at the most.
I always leave out information that is needed so If You need more information just ask if you would , Thank you.

 

Sounds like it's WAY too much pressure.

Carbs don't work off of fuel PRESSURE. Common misconception. Rather, they work off of VOLUME. All the pump has to do, is keep the fuel bowl full. If it could do that at .001 psi, then .001 psi is all you need. That's an exaggeration of course, it does take SOME pressure to force enough fuel through the needle & seat, but the principle should be obvious.

Few carbs can tolerate FP above 7 psi or so. Few need the FP above 3 or 4 psi. If your old one was giving you 4, and the car ran good, then there wasn't anything wrong with it.

Don't outsmart yourself. If I may paraphrase one if the GOATs in a totally unrelated field of activity:

If it RUNS good, it IS good. Likewise, if it doesn't run good, … it isn't.

Why did you disable a perfectly good working mech pump and improperly install an electric one that doesn't work near as correctly? Was there a reason?

 

Thanks for the response , I need 9lb for the nitrous system, it's running through a 750 double pumper. My pressure gauge right before the carb says it is running at 15 or more but this fuel pump is rated for 6-9. The pump isn't regulated . it has no relay and has no safety shut off yet. The part that I find confusing is that the pump stays on. What is suppose to make it start and stop and what is your thought on it running through the computer. It's a 87 body that had a 305 fuel injected, with the pump in the tank originally.

 

I'm going to assume this is a wet shot?

Sounds like you need 2 regulators; one for the carb, set to 4 psi or so, and one for the nitrous, set to 10 psi or whatever. Both should be the return style regulator, not the dead-head type.

The computer turns the pump on & off.

 

[QUOTE=sofakingdom;6315358]I'm going to assume this is a wet shot?

Sounds like you need 2 regulators; one for the carb, set to 4 psi or so, and one for the nitrous, set to 10 psi or whatever. Both should be the return style regulator, not the dead-head type.

The computer turns the pump on & off.[/QUOTE) The nitrous has to be over 750psi and generally around 950PSI and that changes drastically with temp. To run the nitrous , the carb has to be at 8-10 lbs other wise the gas Nitrous mix will be bad, as in to much nitrous , which is real bad. If I bypas the computer what do I need to turn the pump on and off.

 

I have received the regulator and it runs great, So thanks folks your help has been much appreciated.