mrcoolauto

hello folks a costumer came to me that a painter after painting this 1992 ls400 misplaced the key, another key was cut out and started the car, it works but vibrate and shuts off and since then the car has refused to start. I checked it out and has comprssion, it cranks it brings light on my testing lamp testing the the injectors power feed, it has sparks on the spark plugs but it just won't start. I don't have a powerful scantool that have a bidirectional abilities, and the cheap ones I have can't scan any car dated back 1996 ..I will be hoping to hear from you folk's who have dealt with issues
​​​​like this before to give me an insight on what to look out for while performing further diagnostics. thanks.

Moarpower

Check the fuel pump relay and the circuit opening relay.

dicer

You don't need a powerful scan tool it likely won't do much on a OBD1 system. Does it have fuel pressure?
It can be quite a few things causing the problem.

mrcoolauto

i have checked the presure but am not quite satisfied with and locating the fuel pump is another problem

mrcoolauto

its pumping fuel but it doesn't have an outset to check the presure from the fuel pump

Moarpower

It could be timing related if fuel and spark are present.

dicer

I posted a photo some place on how to check the fuel pressure. No one here would give me a special place to put all the good stuff I had taken pictures of.

Dgoll75

I just went through the exact same situation in my 93 in Jan. It was the ECU. I tested and goofed with every little solenoid, tested fuel pump and fuel pump ecu, utilized jumper wires, checked wire harness', yada yada yada. Finally gave in and opened up the ECU. 2 leaking caps. Sent it out for repair. Got it back, plugged it in and car runs flawless again.

mrcoolauto

I doubt cos the customer said and I quote " I gave out the car for body repair and after when there are done painting the car the key got lost, another key was reprinted which was used to start the car and drove it to another paint shop and just right there the car started idling rough and after a while it shuts itself down until this very moment it hasn't started again", so when go there I made some visual inspections put on the ignition and the light on the dash came right up, no alarm sign during my time of diagnostics I only did some manual pressure check from the fuel supply and it was average compared to the pressure I do get from a healthy working fuel pump, set aside that the second thing I noticed was no suction power through the air intake that leads to the maf and air file box, it could be Timing issues that leads to valve stocked open, but there wasn't any sort of engine dismantle before that issues began and I checked the timing belt there don't feel loosed of stuff like that, so it could be the brain box like the other friend said, why? because this is not distributor less ignition system no crank sensor, if it have crank sensor then possible it could be one of the culprit but am not sure, my three things am looking at is fuel pump, ecu and security if at all its have one.

mrcoolauto

This remote part of the world have no such facility and getting hands on another ecu will need it to be reprogramed to work with this system which I don't have that $3,000 scan tool that can handle such task.

mrcoolauto

how did you know the circuit opening relay on ls400 1992 sir?

mrcoolauto

and what could that be?

cdchase32

Did you check all the spark plugs or just one? I had the a similar issue and one of my coils came unplugged.

Moarpower

The relay is mounted on to the ecu. You shouldn't need to reprogram the ecu if you replace it.

cdchase32

The fuel pump is accessible behind the rear seat. Take the back seat out and there is a circular access panel center of the rear wall. It is stuck on with butyl tape.