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Evo GeneralDiscuss any generalized technical Evo related topics that may not fit into the other forums.
Please do not post tech and rumor threads here.
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My car sat last year for a good 4 months. When I got around to driving it again I noticed fuel was tipping pretty lean into the 12s once I started hitting a bit over 4000rpm. Originally it held 11.6-11.8 pretty steadily at full boost with E85.
Here is what I've done thus far that resulted in no changes:
1. Replaced Walbro 255 with a new spare I had
2. Replaced FPR with an AFPR unit (since it was only slightly more expensive than the gauge alone)
3. Observed fuel pressure during a pull and it seemed to work properly at 1lb per psi of boost but it quickly falls back down once peaking
4. Replaced likely dying battery with new one, I have 13.8-14+ V to redline
5. Had injectors sent off to be cleaned/flow tested
6. Tried new fuel
7. New wideband sensor
Not really sure what's going on. Does the IPW look weird? Here is a log from a quick 3rd-4th WOT pull, I let off early for obvious reasons, it only gets worse the higher you go.
Last edited by Turtletron; Mar 21, 2022 at 02:55 PM.
It sat with E85 in the tank for 4 months? Maybe the fuel pump hangers internal filter is clogged/dirty.
Does this happen? I didn't see anything when searching but at this point I'm running out of things to try so an inline filter conversion will probably be next.
Originally Posted by Kevin.
Voltage? fuel pump rewire?
Checked voltage and it was 9v with normal driving and peaked to 12v in the higher rpm
so you were seeing 71 psi plus on the fuel pressure at the top of the pull?
if so, looks like tune to me.
It turns out that the fuel pressure is quickly peaking with a 1:1 psi to boost pressure reading but then it sharply falls as the rpms continue to rise.
It turns out that the fuel pressure is quickly peaking with a 1:1 psi to boost pressure reading but then it sharply falls as the rpms continue to rise.
Changed fuel filter and strainer... No improvement.
Anymore ideas before I buy a new pump even though my old pump and this supposed new pump I bought from a user on here behaved the same way?
so you either have not enough pump for your set up, or you have some kind of restriction on the feed side, or you have to much voltage drop at the pump.
if it was running all fine before and now same setup, and it wont run.
its gotta be the pump or a restriction somewhere....
