NSSANE02

iTrader: (14)

The pump bleeds off after priming no matter what pressure it's set at. At 60psi it will hold pressure at idle and light loads, but under WOT it drops to about 40. I replaced the almost new racetronix pump with another new racetronix pump and it was still doing the same thing. I then replaced the rest of the system with -6 lines, billet rails, and aeromotive reg... still same problem. I recently set the pressure to 70psi (idling) and it holds constant at 70 even at WOT. It sounds to me like the check in the pump is bad but it seems strange that 2 new pumps both have bad checks. Anyone have any other ideas?


BTW, I know I have another thread about this but it was 4 years old and had too much clutter.

Lonnies Performance

iTrader: (16)

The check valves do nothing while the pump is running. If you have a pressure loss at full throttle it is related to pump output or something else bleeding off flow, such as a regulator or internal line leak.

NSSANE02

iTrader: (14)

If that's the case, why would the pressure hold solid with it set at 70psi? The only way that would make sense is if the regulator was bad but I put the stock reg back in and it was still dropping. This whole time I've been thinking that there was an internal leak in the bucket somewhere but a leak wouldn't stop at a higher pressure.

poltergeist 02

iTrader: (65)

What style clamp did you use on the flex hose that goes on the pump outlet?

NSSANE02

iTrader: (14)

The worm gear that came with the kit. Still, if it was leaking there and not able to hold 60psi, why can it hold 70?

poltergeist 02

iTrader: (65)

If it is leaking at a consistent rate and only allows a certain amount of fuel to squeeze through, then adding pressure may have just masked the problem. The only time I have seen a fuel pressure loss problem with a new pump @ WOT, it was caused by either an in tank leak, voltage drop at higher rpm, bad regulator, kink in the feed line or the pump is too small for the setup.

NSSANE02

iTrader: (14)

I guess the only thing it could be at this point is an in tank leak. It just seems really strange to me that it would drop 20psi while set at 60 yet doesn't drop even 1psi while set at 70. No matter, I decided to switch to E85 so I have a complete new fuel system on the way. If it's still losing pressure after that I'll get a new sending unit and be done with it.

Inssan

Could it be a fuel press gauge/sender issue? At 70 sensor works but below 70 the added vibration causes an issue? Does it loose power?

NSSANE02

iTrader: (14)

Not a gauge issue, I confirmed the drop with a mech. gauge and it goes lean when drops to 40 and super rich at 70.

Lonnies Performance

iTrader: (16)

The kinked line sounds possible as the added pressure could hold it open.

Not an easy one to diagnose for sure.

NSSANE02

iTrader: (14)

I suppose it could be a kinked line but also seem very unlikely. I've had the pump out at least a dozen times trying to figure this crap out and have tried to be careful putting it back in each time. I got my new E85 pump today so I'll swap that out and be sure to seal everything up. Hopefully the problem will go away then.

Thanks for the input guys, this thing is confusing the hell out of me...

poltergeist 02

iTrader: (65)

Any update on this?

samdogmx

iTrader: (14)

Im guessing regulator. Have you tried swapping it out for a different one yet?

poltergeist 02

iTrader: (65)

He swapped the whole fuel system and was still having this issue.