stumble with gt500 pumps

[Wicked One]

I have dyno time for next Saturday. In the meantime I am going to go over everything .........again and again....oh yeah....and again.

What gets me is the lack of fuel pressure drop during stumble. To go with a return system is not economically possible right now. Maybe later.

Will keep this updated with all I find or what doesn't work.

sent from my Damn phone

 

[JeremyH]

IMHO the stable fuel pressure during the stumble and lean a/f spike would point towards something in the tune that needs tweaked.

Best of Luck with this Gregg!

 

[Wicked One]

small update,

Car did ok. Still has the stumble but is a lot less now. The tuner is doing all he can. It stumbles under a load, and sometimes around both corners and sometimes just the right or left. I am leaning towards a mechanical issue not a tune, but still looking.

 

[Fake_Snake]

i have the same issues you have with these pumps but somethign that confuses me is i have a gt500 ecu and the factory gt500 pumps the stock fpdms..

my issuses still are:
1. speratically at the press of the throttle will lean out and climb lean the more i give untill i let off and just gradually give ti gas. were talking will jump from 14.8-17-18-19 af and stumble

2. gauge level has yet to work correctly even after the sending unit replaced, lever fixed.. usally if "about" half a tank if i idle for a few min the gauge just drops and low fuel light comes on... i recently ran out of gas and im thinking it might of reset the system cause its not dropping i will be watching it this week..

3. a/f will randomily spike to 17's at tip in at times...

 

[Wicked One]

The fpdm for the gt and gt 500 are the same. The additional one starts with I think 7r.

You and I are having the exact same problem. My fuel gauge did the same thing at half tank, went to empty. When I got gas it took 10 gallons so I know I was not empty.

For shits and giggles, I might put my stock pump setup with the bap and single fpdm back in and see if that helps. Then I can really see if it is hardware or computer.

Will let you know what happens.

sent from my Damn phone

 

[Fake_Snake]

Yeah please do . [email protected] is my email

 

[Fake_Snake]

anything new with this.. tuner called me and said next time it stumbles to disconnect battery see if it fixes it and if that does its prob in the adapitive learning for me

 

[Wicked One]

The only thing new was the motor blew up. The plug melted/broke and destroyed the head and one piston.

I got a new head and piston, all put back together, does the same thing. I am trying to get the data logs from the tuner, but that seems like too much of a task for him. I can data log it myself, but do not want to risk anything happening.

Car is going in for paint then off to Lund for a tune.

I have a new fuel system, it is a single walbro 400 with Bap. Taking out the dual fpdms and 2 pumps should narrow down the issue. IF that doesnt work, I am going to go back to stock fuel system and the 4" pulley and the original tune that I had before going forged.