fuel pump issues?
Yours actually shows more pressure than mine. I'm at about 40 - 42 idle and 30 - 32 with car off. Seems to be a normal thing with this set up. Well, maybe I shouldn't say normal but same thing is happening. I guess it's like someone mentioned on this thread, pump is overrunning fpr. I will still check relays since I have an evo junkyard close by. I can get a fuel pump resistor for $30 so I'll go there with a multimeter and get one that shows a reading within spec. Maybe I should get relays 1 - 3 new since they're not that much online?
EvoM Community Team Leader
Joined: Aug 2005
Posts: 5,690
Likes: 708
From: West Coast
i never really stated this, but i was never concerned about the exact pressure numbers (unless they looked really low) you where getting. I was really only ever interested in the behavior of your fuel system. This is for a couple reasons, I put very little faith in the accuracy of those little mechanical fuel gauges, so the exact numbers aren't the most reliable in my book, but they can be useful. Second, your stated problem was a lean condition, and in that context too much fuel is probably not going to be the problem. Lastly the combo of walbro 255 and stock regulator/lines is so common, I have that setup myself, and nobody has problems with it. Its pretty common to hear that you need a retune after installing an upgraded fuel pump, and dealing with that few PSI might just be wrapped up into that. I have never actually checked my fuel pressure at the rail, but I scaled my injectors, tuned my fuel map, and watch my fuel trims and I never have had a problem. The base fuel pressure is arbitrary, it could be what ever you want it to be so long as the ECU is properly calibrated to deliver the correct IPW for the desired Air fuel mixture. The fuel trims are the canary in the coal mine to tell you if this is working properly or not. The ecu will automatically adjust the fuel trims to try and get the AFR it wants for Idle and cruise, so if you see large numbers in the fuel trims you know the ecu isnt calibrated (tuned) properly for your specific setup.
Sorry for the wall of text but after all this noise i thought i would lay out my thought process on this. I think these guys have you chasing your tail trying to figure out why your fuel pressure is reading to high, but troubleshooting is all about no stone left unturned.
To take stock of all you have learned though, your high/low voltage circuit works and hasnt been bypassed, your regulator is working, your fuel pressure isnt to low. Your resistor might be out of spec, but it apparently isn't hurting your pressure at idle (at least when you have tested it, could still be heat related). The thing i'm still interested in seeing are the fuel trims, that will really open up a window into what the ECU is doing.
Sorry for the wall of text but after all this noise i thought i would lay out my thought process on this. I think these guys have you chasing your tail trying to figure out why your fuel pressure is reading to high, but troubleshooting is all about no stone left unturned.
To take stock of all you have learned though, your high/low voltage circuit works and hasnt been bypassed, your regulator is working, your fuel pressure isnt to low. Your resistor might be out of spec, but it apparently isn't hurting your pressure at idle (at least when you have tested it, could still be heat related). The thing i'm still interested in seeing are the fuel trims, that will really open up a window into what the ECU is doing.
Hey man I really appreciate you and all the guys that have chimed in this thread. All ideas are good ideas. I have learned a lot in this thread and those that have a similar issue will have this thread to read through and help figure it out. I still think it's heat related but then there's this. When it goes lean at idle and it's hot outside, fuel pressure is still the same. Sometimes, specially when it's cool out it'll be rich at idle instead of lean and it will try to find 14.7 mark but it seems to not be able to thus staying around 13.8 - 14.2 ish. This tells me it has to be something with electricity (sensor,relay,resistor maybe)? I will try to figure out how to log the fuel trims like you explained and post it here for you guys to see. That's the only thing left to do I think. Also, I will try to get another resistor that's in spec. For $30 used its worth it. Lastly, if alll else fails I may replace all relays since they're relatively cheap. Drive ability and wot are fine but remember the main issue was the fuel pump making a super loud noise when it was hot out which hasn't happened again since it's been cool out lately.
so im trying to log this ****...i hit start datalogger and its logging but what am i supposed to do from there? I hit stop datalogger and it stopped but how do i see the info or save it?
EvoM Community Team Leader
Joined: Aug 2005
Posts: 5,690
Likes: 708
From: West Coast
yah, it showed your trims at 0 and 0. Which is strange, either your cars memory was wiped recently and it hasn't learned them, your scalings are dead perfect (not likely), or your car is not going into closed loop and learning the trims. Try running the car and logging Fuel trim in use and the oxygen feedback trim as well and post your log. Do this while letting it idle for like 10 minutes.
I know this has nothing to do with this thread but you seem to know some stuff biggie so tell me what you think. I was at a friends house and we were redoing some of the exhaust so I disconnected the battery and now the car idles at 1200 rpms. Still drives fine etc. Could it be relearning or something?
EvoM Community Team Leader
Joined: Aug 2005
Posts: 5,690
Likes: 708
From: West Coast
I know this has nothing to do with this thread but you seem to know some stuff biggie so tell me what you think. I was at a friends house and we were redoing some of the exhaust so I disconnected the battery and now the car idles at 1200 rpms. Still drives fine etc. Could it be relearning or something?
awesome thx man...havent had a chance to log the fuel trims...tomorrow im taking my kid to universal for his birthday so maybe when i get back ill log it...now i have to try and find a muffler...look at what the previous owner did...im thinking buschur sd maybe?
Evolved Member
Joined: Mar 2014
Posts: 816
Likes: 82
From: wisconsin
i never really stated this, but i was never concerned about the exact pressure numbers (unless they looked really low) you where getting. I was really only ever interested in the behavior of your fuel system. This is for a couple reasons, I put very little faith in the accuracy of those little mechanical fuel gauges, so the exact numbers aren't the most reliable in my book, but they can be useful. Second, your stated problem was a lean condition, and in that context too much fuel is probably not going to be the problem. Lastly the combo of walbro 255 and stock regulator/lines is so common, I have that setup myself, and nobody has problems with it. Its pretty common to hear that you need a retune after installing an upgraded fuel pump, and dealing with that few PSI might just be wrapped up into that. I have never actually checked my fuel pressure at the rail, but I scaled my injectors, tuned my fuel map, and watch my fuel trims and I never have had a problem. The base fuel pressure is arbitrary, it could be what ever you want it to be so long as the ECU is properly
I calibrated to deliver the correct IPW for the desired Air fuel mixture. The fuel trims are the canary in the coal mine to tell you if this is working properly or not. The ecu will automatically adjust the fuel trims to try and get the AFR it wants for Idle and cruise, so if you see large numbers in the fuel trims you know the ecu isnt calibrated (tuned) properly for your specific setup.
Sorry for the wall of text but after all this noise i thought i would lay out my thought process on this. I think these guys have you chasing your tail trying to figure out why your fuel pressure is reading to high, but troubleshooting is all about no stone left unturned.
To take stock of all you have learned though, your high/low voltage circuit works and hasnt been bypassed, your regulator is working, your fuel pressure isnt to low. Your resistor might be out of spec, but it apparently isn't hurting your pressure at idle (at least when you have tested it, could still be heat related). The thing i'm still interested in seeing are the fuel trims, that will really open up a window into what the ECU is doing.
I calibrated to deliver the correct IPW for the desired Air fuel mixture. The fuel trims are the canary in the coal mine to tell you if this is working properly or not. The ecu will automatically adjust the fuel trims to try and get the AFR it wants for Idle and cruise, so if you see large numbers in the fuel trims you know the ecu isnt calibrated (tuned) properly for your specific setup.
Sorry for the wall of text but after all this noise i thought i would lay out my thought process on this. I think these guys have you chasing your tail trying to figure out why your fuel pressure is reading to high, but troubleshooting is all about no stone left unturned.
To take stock of all you have learned though, your high/low voltage circuit works and hasnt been bypassed, your regulator is working, your fuel pressure isnt to low. Your resistor might be out of spec, but it apparently isn't hurting your pressure at idle (at least when you have tested it, could still be heat related). The thing i'm still interested in seeing are the fuel trims, that will really open up a window into what the ECU is doing.
Well put! sorry about all the crappola Biggie
Those are really nice welds, they look like my coworker stevens work!