Lexuszeal Posted January 3, 2008 Posted January 3, 2008 I am having the similar issues with my 91LS4hundred as 'blessed' and 'Vincyray'!! So far I can continue to start the car and it runs awhile then dies--from here it will not fire back up but I cant crank it as long as I want. Some hours later I can restart it and the process begins again>>> In the beginning the CEL codes indicate 24 air intake temp sensor. Ok?? Just today I figure when it dies I check to see if there is spark-- no spark in all wires! but how can I restart it hours later?hmm Check to see if there is fuel while it wont start also..crank crank crank and no fuel at all running through lines- cut off! Normally I will check the CEL codes after it dies but today there is no check engine light or O/D light when I do the diagnosis and when the ignition is in "on" position. hmmmm However I will be able to restart it here in an hour... what the bleep does this indicate is going wrong with my car? Not the ECU is it? What can I do? <_<
Lexuszeal Posted January 4, 2008 Author Posted January 4, 2008 Changed my 20amp EFI fuse b/c it was blown so now I have CEL and O/D light along with spark on all wires. Definitely no fuel still so I will have to look into my fuel pump and or fuel filter but I cant figure why it would work intermittently so this is surely a tricky diagnosis!
SKperformance Posted January 4, 2008 Posted January 4, 2008 It sounded like the fuel pump was not working in the first place . Make sure the battery is fully charged. turn the key to run not start and listen for the fuel pump in the trunk. No whirring noise ,no pump.
Lexuszeal Posted January 5, 2008 Author Posted January 5, 2008 So today I remove my fuel pump from the tank to see if it works- i hook it to a battery and voila it does in fact work! But just before removal I turn my key to "on/run" and no fuel pump operation... even when B+ and Fp are bridged! I reinstall the fuel pump as I know it works.. turn the key to on and hear it working b/c the lines were free from fuel. try to start the car and the engine would not start.. soo i turn the key to on again and no operation of fuel pump even with B+ and Fp bridged?? Ok Strange so I am led to believe now that I have a completely blocked fuel filter because I have no fuel pressure at the fuel rails. And if I remember correctly the fuel pump will not operate if it believes there enough pressure in the lines.. so this would have to be the fuel filter right? I am stumped
SKperformance Posted January 5, 2008 Posted January 5, 2008 Fuel filter is a good starting point. Is the relay for the fuel pump functioning properly?
Lexuszeal Posted January 5, 2008 Author Posted January 5, 2008 How can I be certain that the relay is functioning to specifications?
SKperformance Posted January 5, 2008 Posted January 5, 2008 1 is to test the connectors on the block then see if jumping the posts activate the pump. Sometime the relays open up when pulled and you can see corrosion.
Leadfoot Posted January 5, 2008 Posted January 5, 2008 1 is to test the connectors on the block then see if jumping the posts activate the pump. Sometime the relays open up when pulled and you can see corrosion. You could also swap over the relay thats next to it, I think its the horn relay, the starter relay is also the same wiring config but I am not sure if that one fits. If your horn works before the swap over and not after then you might have a culprit.
C.P. Posted October 21, 2022 Posted October 21, 2022 (edited) I have the same condition with a 1995 Lexus LS 400; The car has been bullet proof until now The engine turns and "starts to start" and then dies; no trouble codes either; one mechanic told me it was the ECU (a common problem for older cars); so I replaced 6 capacitors in the ECU and nothing has changed; The fuel filter was replaced 15K miles ago; Could the fuel filter be completely blocked in 15K of driving? What else do I check. Have replaced the started relay and fuel pump already - have confirmed the fuel pump is running (hear it running when trying to start) I am totally-totally stumped on this and need help. Thanks, C.P. Edited October 21, 2022 by C.P. added more data
paulo57509 Posted October 24, 2022 Posted October 24, 2022 How bad were the capacitors (in the ECU) you replaced leaking? The stuff that leaks can damage the middle layers of the multi-layered PCB. When you replaced the fuel pump, was the pickup screen also replaced? Long shot, but I think there's a second fuel filter inside the tank (P/N 23300-50060).
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