engine won't start

[JDMCelsior]

My 91 LS400 won't seem to start up. Did anyone have this problem before?? It cranks and stays on for 1-2 seconds and then dies out. One day i drove it, then i came back to it and it wouldn't start. Im thinking its the hoses or the fuel filter?? any suggestions on how to fix this???

 

[Guts]

I`d guess fuel blockage or the fuel pump isn`t pumping the amount of fuel it should.

 

[Zuffen]

I'd start by replacing the fuel filter.

They're cheap and it's easier to replace than the fuel pump.

When replacing the filter you could try putting compressed air (at about 60psi) up the fuel line and listen at the gas cap (with it off) for the fuel and air comming through. If you wanted to be safe you could diaconnect the fuel line before the fuel rail so you didn't force any rubbish past the injectors.

Remotely it could be an ECU problem as the ECU kicks up fuel pressure to start then drops it once the engine is running. Although this does re-inforce Guts suggestion.

 

[krayn]

Could be fuel pump balast resistor????

 

[JDMCelsior]

well, i've changed the fule filter but still the car doesn't stay on. Any other suggestions??? How can we tell if its the fuel pump thats not working, because i know thats expensive and i don't want to replace it if its not the problem

 

[madmont]

What about the IAC valve?

 

[Zuffen]

If you don't have access toa fuel pressur gauge you can do the following rough test of the fuel pump. Disconnect the fuel line in the engine bay and have someone turn on the ignition and see how fast the fuel flows into a bucket.

If it's flowing fast try blocking the end of the line with your thumb and try the ignition again. There should be enough pressure that you have trouble holding it back.

Don't do either for more than a second or so as fuel may well spill and it has atendency to ignite.

The real answer is take to your mechanic and see what he has to say.

 

[JDMCelsior]

i've spoken to my friend who had a SC400 and had the same problem. He says his problem was the ECU but he bypassed it by rigging a wire from the diagnosis box (FP to the B+). Can anybody explain why this would happen and how to actually do this rigging??

 

[JDMCelsior]

well, somehow by luck the car started up. But once we start driving it, it dies out!! anybody know whats wrong now???? fuel pump seems to be working =)

 

[KDog]

That line is to bypass the fule pump speed controller. If basically turns your fuel pump fully on. Have you tried bypassing the fule pump just to make sure its not the problem?

 

[sideshow]

i have fixed afew soarer v8s with similar probs

first one was a bad connection on the efi relay
or bad earths on efi relay fuel pump relay and circuit opening relay
all under the fusebox at front and all use common earth
so i joined all the earths together and put to an extra earth spot on chassis

theyre near battery and this car had abit of corrosion near battery

and i also tightened pins on efi relay

this soarer was cuttin out as soon as the car hit about 6 kph on the road
on stands in the air it was fine

another prob i have fixed was a bad earth on the main ecu earths for the injectors

this earth bolts to the back of the block and the engine had been changed afew months or so ago so i gues it might have come loose

when crankin the injectors would cut out due to so much current from styarter motor
the 2 main earths for th erinjectors on the ecu are the culprit
i added 2 new earths for those wires and fixed it
it seemed like a blocked fuel filter prob at first but after cleanin fuel filter and nearly stuffing the fitting on it
refitied filter cause it was clean then did more tests and found bad earth