96 ls400 fuel issues
Thread Starter
Driver School Candidate
Joined: Apr 2014
Posts: 31
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From: FL
96 ls400 fuel issues
So upon driving to work today, my LS started to be unresponsive to the gas pedal, and would not rev up. I kept tapping the gas and it would slowly climb in RPMs but not accelerate very much. It then died out. I also had low oil, so I put in 3 quarts and let her sit for three hours. Returned back to the car and she fired up so I could drive it to work, then letting it sit for another two ours. Went to leave work, and now she won't start again, at all. I've replaced the pump and filter, though I cannot hear it surging after turning over. Almost positive it's a fuel issue (unless ECM). Any way to bypass the pumps relay on this model? And can it possibly be the ECM? Getting a can of starting fluid now to make sure it's a fuel delivery problem. I'll keep an update, thanks.
Thread Starter
Driver School Candidate
Joined: Apr 2014
Posts: 31
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From: FL
Replaced the pump prior to a starting problem, but it turned out to be another reason related to an engine relay problem. Anyu way to bypass the pump relay though? I know on the 90-94 it can be done through the engine diagnosis port, haven't found anything on this model yet.
Thread Starter
Driver School Candidate
Joined: Apr 2014
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From: FL
Okay so I know it's fuel.. Upon spraying starter fluid into the intake she will fire up. Waiting on anyone that may know how to diagnose this models relay? So I can tell before diving into the pump again
Thread Starter
Driver School Candidate
Joined: Apr 2014
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From: FL
So here's where I'm at. It's not the relay.. Surprisingly found one at Autozone (for a whopping $50) and put that in with no results. Also, I am finding no good leads as to if there even is a fuel pump ecu in the 96's, can't even find any shopping around, and I figured there's no need for one with the relay in place. So it's pretty much down to the pump itself, which I literally replaced a month and a half ago.. But at least it's under warranty. Thanks for the help guys, I'll let you know how that goes tomorrow.
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Thread Starter
Driver School Candidate
Joined: Apr 2014
Posts: 31
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From: FL
One thing after another.. I solved the fuel issue and got her running by replacing the ECU with a spare one I bought a while ago. So now she's misfiring cylinder 6, and a further obd reading shows it had a history of this misfire? Whatever that may mean, I replaced the passenger coil pack that controls 2 4 6 and 8, and my problem still persists. It's to the point that I'm burning $10 of 93 in about 10-15 minutes. Any ideas here?
CL Community Team
Joined: Aug 2011
Posts: 4,188
Likes: 1,011
From: Japan
Sounds like your spare ECU has a serious problem judging from the blinking problem. Was it confirmed good before you bought it? I find many of junkyard ECUs are not in good conditions.
Incidentally, how did you fix your fuel problem? Did the spare ECU fix it or did you replace the fuel pump again to a better one?
Incidentally, how did you fix your fuel problem? Did the spare ECU fix it or did you replace the fuel pump again to a better one?
Thread Starter
Driver School Candidate
Joined: Apr 2014
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From: FL
Yamae, just put a post on the huge "all my problems fixed" thread about the two ECUs. If you would assess that question, you may just solve all my crazy problems. It is indeed, regarding leaky caps.
CL Community Team
Joined: Aug 2011
Posts: 4,188
Likes: 1,011
From: Japan
Leaky capacitors damage the board and it is the often case that the board can't be fixed. Replacing them before the leak starts, you can prevent the damage as well as you mostly get the better engine performance as is close to a new.
Aged Nichicon PF(M) and PR(M) capacitors loose the capability to bypass the AC components and cause different problems since the ECU can't work as is designed. I'd recommend to replace them all when aged. The parts cost is only $10. I have seen many people who didn't want to do so and spent big money and his/her energy to fix the car. I don't want to add your name to the list who have wasted a lot.
Aged Nichicon PF(M) and PR(M) capacitors loose the capability to bypass the AC components and cause different problems since the ECU can't work as is designed. I'd recommend to replace them all when aged. The parts cost is only $10. I have seen many people who didn't want to do so and spent big money and his/her energy to fix the car. I don't want to add your name to the list who have wasted a lot.
Driver School Candidate
Joined: Feb 2021
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From: Jatim
Sadly, i couldn't find all the capacitors on the list in my country 
Leaky capacitors damage the board and it is the often case that the board can't be fixed. Replacing them before the leak starts, you can prevent the damage as well as you mostly get the better engine performance as is close to a new.
Aged Nichicon PF(M) and PR(M) capacitors loose the capability to bypass the AC components and cause different problems since the ECU can't work as is designed. I'd recommend to replace them all when aged. The parts cost is only $10. I have seen many people who didn't want to do so and spent big money and his/her energy to fix the car. I don't want to add your name to the list who have wasted a lot.
Aged Nichicon PF(M) and PR(M) capacitors loose the capability to bypass the AC components and cause different problems since the ECU can't work as is designed. I'd recommend to replace them all when aged. The parts cost is only $10. I have seen many people who didn't want to do so and spent big money and his/her energy to fix the car. I don't want to add your name to the list who have wasted a lot.