255 walbro installed and check engine came on...

7mgangsta

New Member
Mar 19, 2011
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St. Paul, MN
I just installed a Walbro 255 and did the fp relay bypass and the check engine light came on and wasn't on before. Anyone have this happen?
 

toyotanos

What will we break today?
Staff member
Super Moderator
Nov 29, 2008
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Coon Rapids, MN
If the only thing you touched was the pump/relay, then my shot in the dark would be a rich AFR code (26 iirc) due to the J-tube not being drilled out/bypassed with the big pump. BUT, since we have no code info I'm useless!

But seriously, pull the codes and report back here for further help :)
 

7mgangsta

New Member
Mar 19, 2011
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St. Paul, MN
Yea, I put a fuelab AFPR in and put in a fuel feed damper bypass in too so the J tube is no longed in use. But My car is still running lean as hell lol I'm about to just junk it after 3k in upgrades lol I'm going to pull the intake manifolds off, turbo manifold off and pull the head off to check the head and install new MHG with new manifold gaskets. I tested it positive for combustion fumes in the coolant with an HKS MHG... How do I check engine codes on the 89 7mgte oh ps I'm running a safc 2 and it's almost maxed out, 550's lex afm intercooler and hardpiping. Thanks.
 

TurboStreetCar

Formerly Nosechunks
Feb 25, 2006
2,776
3
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Long Island, Ny
7mgangsta;1704134 said:
Yea, I put a fuelab AFPR in and put in a fuel feed damper bypass in too so the J tube is no longed in use. But My car is still running lean as hell lol I'm about to just junk it after 3k in upgrades lol I'm going to pull the intake manifolds off, turbo manifold off and pull the head off to check the head and install new MHG with new manifold gaskets. I tested it positive for combustion fumes in the coolant with an HKS MHG... How do I check engine codes on the 89 7mgte oh ps I'm running a safc 2 and it's almost maxed out, 550's lex afm intercooler and hardpiping. Thanks.

How is it lean as hell with 550's and lex afm? Unless you mean maxed out pulling fuel with the Safc. Leads to my next question of how do you know its lean? Do you have a wideband? If you know its lean then that would likely be the issue, Though usually lexafm and 550's run rich.
 

7mgangsta

New Member
Mar 19, 2011
35
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0
St. Paul, MN
Nosechunks;1704463 said:
How is it lean as hell with 550's and lex afm? Unless you mean maxed out pulling fuel with the Safc. Leads to my next question of how do you know its lean? Do you have a wideband? If you know its lean then that would likely be the issue, Though usually lexafm and 550's run rich.

Yea, I have an AEM wideband that reads around 16 idle and 12.5 at about 25% throttle and it goes lean and bogs out around 10 vacuum on the boost gauge. Base fuel pressure is 43.5 lbs which is what my precision 550's call for. I even called the tech there. I'm going to pull the intake manifolds off, check everything and do a new metal head gasket or clean it and seal it, with new manifold gaskets. Pretty sure there is a leak in the manifold gaskets and I know there is combustion in the coolant. I haven't checked code yet. I will tomorrow.
 

TurboStreetCar

Formerly Nosechunks
Feb 25, 2006
2,776
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38
Long Island, Ny
Fuel pressure needs to be set to fit you particular setup. A generic number will not work for every car the same way.

First you need to zero the safc, set fuel pressure to stock spec, and check the VF signal so you can see what the TCCS is doing. Then based upon the VF signal adjust the fuel pressure to get a general reading of ~2.5v across the board. Once the VF signal is roughly stabilized to neutral, make small adjustments to the safc untill VF perfectly stable at 2.5v.

VF will zero out in open loop operation like WOT so disregard those readings.

Make these changes to get the engine running properly as a baseline before you tear it apart so if something goes wrong on the rebuild you know it ran fine before.