Weird problem after a fuel pump change

[Superdave]

Car is a 3rd gen Sunfire, 3500 swap with a P&P'd top end, Street/Strip cam, etc.. OBD1 piggybacked for the engine. $A1/'7730. 36lb/hr injectors.

It had the original fuel pump from the 2.2, upon tuning I determined that it just couldn't keep up with the engine. I maxed out the VE tables trying to get WOT to around a 12.5:1, even with a dramatic BPC change it just couldn't supply enough for the engine.

The owner purchased a 255lph pump kit from Racetronix for the 3rd gen Jbody and installed it. He brought it over last weekend for some datalogging/tuning. To our surprise it now will not rev past 6K. Once you get close to 6K it just falls on it's face like it's hitting a rev limiter (which is set to 7).

He's called the vendor and is waiting for a response from them but i figured i'd ask here to see if anyone's seen it before.


I can post the datalogs if anyone wants to see them...

[MidnightriderZ24]

is this verified with a pressure gauge dave? maybe a line is pinched, or something overlooked?

[Superdave]

Haven't checked the pressure yet.

The day we logged had some weird weather conditions and i noticed that the MAP was only getting up to around 85kpa @ WOT. I wanted to make sure that it wasn't pulling too much vacuum on the FPR so we un-hooked it. It acted a little better but i didn't get a chance to log it after. I'm hoping for Monday afternoon.

[1988GTU]

This a E 85 car? The FPR can clog up with debris from fuel corrosion and give funky driveability issues.

[Superdave]

Nope, normal gas.. probably E-10 since we're in Iowa.

[kflo 93 gt]

Modify the bucket so it gets more fuel flow. I'm guessing it's sucking the bucket dry.

[Schmieder]

Not sure if you considered this but, cheap fuel pump filters don't flow as well. I got an ACDelco filter which was much more expensive (for a filter anyways) as they are designed to flow better. Suppose the draw is enough to collapse the pump filter upon itself?

Just an idea tossed out there.

[Daguse5853Z]

I remember reading about bootleg walbro fuel pumps a few years ago.....3x00 modified might be able to chime in on that one

[1988GTU]

I remember reading about bootleg walbro fuel pumps a few years ago.....3x00 modified might be able to chime in on that one

I posted about it and informed a few members about it........ IIRC I told Jon about it (3100-modified)

[Superdave]

we haven't really done a whole lot with this, i think he contacted Racetronix but not sure what they said...