Cutting out under load

[1989Flyboy]

Stutters and hesitates at >75% throttle

-Initial fuel pressure after prime was around 42#.
-Jumped to approx. 56# after start.
-flucuate 2-3#'s while accelerating.
-would jump 5-6#'s while aggressively revving engine while cruising with clutch in.

Any suggestions?
My gut is thinking the fuel pump. Seems like a bit of work for guesswork.
2001 ws6 convertible with 29,xxx - Absolutely CANNOT do the trap door mod.

Thanks for reading.

[DoctorJ]

i would also say fuel pump too op. i did some quick google looking and read possible issues can be related to dirty iac valve. also might want to check your pressure. the long shot suggestion i will say is a doing an evap purge.

[1989Flyboy]

Thanks Dr.J - pressures are in original post. I did clean the maf, I could also go back and try cleaning IAT sensor.

[1989Flyboy]

Sorry, just realized I read you wrong.... iac???

[SMWS6TA]

IAC - Idle Air Control = Really only used during Idle.

MAF sensor could be dirty or possible vacuum leak.

But if those are the pressure readings while under load then it is most definitely either fuel pump or regulator or both.

How old are they?

You should maintain 56psi even under load. The stock output of a LS1 doesn't overload the system that much like it would if you had a high hp or boosted car.

With my Racetronix Walbro fuel pump I see 58-60psi. Under load it never moves, even at WOT.

[nathan c]

I just replaced the fuel pump in my car 2 months ago. Hate to say it, but the access panel way is a lot faster and easier than dropping the tank. Good luck!