Possible fuel pump?

[TOOMANYTOYS]

Been chasing a lean condition that shows with audible detonation. Thought I had it nailed with a broken injector. No such luck. While looking at my fuel pressure gauge I noticed it was at 23psi with the vac line on so I popped it off and raised it to 43psi line off. Took the car out for a drive and the detonation is worse. Disgusted I parked the car for the night. This morning I started the car and the fuel pressure is now 43psi with the vac line on. I let the car idle for a while and the pressure slowly dropped down to 35psi line on. Seems like the pump starts out strong but then starts to slip after about 10 minutes. The car is hot wired but the pump is unknown. Voltage is between 12.9 and 13.1. Previous owner told me he had a Cottons "stage one " fuel system installed. I've no idea what that is. The only thing I can verify is there is a Hotwire and there are 60# injectors in it.

Sound like a fuel pump or should I be looking elsewhere? If I do need a pump do I still go with the walbro 255 or is there better now?

 

[ScottHeidinger]

It could be a fuel pump issue or it could be FPR or vac issue. Is the fuel pressure rising 1:1 with the boost? I have seen my fuel pressure start at 43 line on when the car is first started cold. Once it's warmed up I've seen very low 30's at idle. Before you spend money on a new fuel pump I would verify what you have unless it's really old. I helped a friend install a double pump in the late 90's and when we pulled the old pump it had part of a garden hose instead of a sock on it and it was actually working fine. I have seen issues with the small section of hose from the top of the pump to the hanger cracking causing low pressure issues. Those little fuel pressure gauges on the rail are often not accurate either. I assume the fuel filter is good?
If you feel good about your hot wire (relay included), filter and FPR then it might be time to drop the tank. If I wasn't sure about the pump or how old it is then I would replace it. I figure a new pump is cheap insurance especially if you don't know what you have or how old it is.


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[TOOMANYTOYS]

The car pulls 19 inches of vacuum at idle and that is consistent. The adj reg is a accufab. I tapped on the reg while the car was idling with no change in pressure

 

[The Granny]

What fuel pump you decide to go for depends on your combo and goals for the car. Take a look in the E85 section for marleyskater420's post titled "What fuel pump do I need" and it'll outline how you can go about choosing the right pump for your goals. The 255lph pump from Walbro is a good option, it flows a good amount at the higher fuel pressures that we need for when we're in boost. It's ideal for applications 500hp. I could be wrong on that HP number but it's in that neighborhood, I know that for sure. it's been a while since I looked at its flow chart. I personally have two external 255's, I believe the part number is gsl392, on my car with the second one kicking on through my XFI system once I'm in boost. The 255 is a relatively cheap pump too I paid around $100 for mine, so it wouldn't break the bank to eliminate a potentially bad pump as a variable in your quest to solve the issues you've mentioned. hope that helps somewhat


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[TOOMANYTOYS]

A 255 pump is more than enough. I just want a good strong running car. I'm getting too old to be racing and breaking stuff every other week. Thanks for the help