New Member 1992 Ls400 Wont Start Please Help!

[CRLS400]

Hey all,

I just purchased a 1992 LS400 that won't start and I wanted to ask your opinion before I begin diagnosis. I'm an automobile restoration mechanic by trade so I'm not afraid of cars but I work mainly on pre-1970 vehicles so computer brains aren't my thing. Anyway, the guy I bought it from (an honest friend) rear-ended someone and cracked the driver's headlight, grill and dented in the bumper a little - a real minor accident. He said he shut of the car - which was and had always operated perfect up until this point - and when he went to restart it the car wouldn't start. He had it towed to his condo and tried to start it again and nothing happened. He eventually wore down the battery trying to start her every few days. About a month later he tried again with a borrowed battery and no dice. I bought the car and installed a new battery. She'll turn over and over but won't fire. I was wondering if these cars had a fuel pump inertia cutoff switch in them. I know Range Rovers have a switch that senses an impact and shuts of the fuel pump so fuel doesnt spew everywhere. You have to push the button back in manually to reset them or they'll never start. Sorry about the long post. Any advice is greatly appreciated. Thanks!

[SKperformance]

Sorry i don't know about any fuel pump cut like the ones ford use on any Toyota.

Have you checked for the fuel pump functioning ?

Spark at the boots?

Try locking then unlocking the drivers door with the key with a good battery in the car.

Any fuses blown?

[CRLS400]

Sorry i don't know about any fuel pump cut like the ones ford use on any Toyota.

Have you checked for the fuel pump functioning ?

Spark at the boots?

Try locking then unlocking the drivers door with the key with a good battery in the car.

Any fuses blown?

Thanks so much for the reply! Stinky - I was really hoping oit was as simple as reseting the cutoff switch lol! There are no blown fuses. I installed a new fully charged battery and unlocked the driver's door with the key - no luck starting. She does have another aftermarket alarm with a toggle switch under the dash and an LED and neither the prior owner nor I really know how it works (although in one position the light goes out so I assume it's disarmed) but the accident could have done something to it. Where exactly is the fuel pump in this car?

[SKperformance]

Fuel pump is in the trunk where the fuel tank is wedged between the tunk and rear seat.

If the car has an aftermarket alarm then there is no use trying to repair the car until it is either taken out or disabled.

If it has a switch that lights up the LED then you want to have the LED on as that is valet mode and disables the alarm and its starter or fuel pump kill.

Try turning the switch on so the led lights then starting the car.

Also see if you can find where the alarm is installed and disconnect the harness.

[sha4000]

i had an aftermarket alarm on my 91 and every so often it would affect the ther car and it wouldnt start no matter what i did. i would just have to leave it and try every so often until it would start. finally i just disconnectedthe alarm and it nevedr happened again

[CRLS400]

i had an aftermarket alarm on my 91 and every so often it would affect the ther car and it wouldnt start no matter what i did. i would just have to leave it and try every so often until it would start. finally i just disconnectedthe alarm and it nevedr happened again

Thanks for the help guys. I've tried starting her with the alarm light on and off no difference :( So I'll be trying to remove it tomorrow. I also had a buddy of mine turn the key while I had my hand on the fuel pump relay in the engine bay - no click - the relay's not engaging. I pulled the relay and could manually operate the relay with jumper wires. Is the relay supposed to engage (click) when the key is in the on position or only when the starter is turning the engine? I get 12v to one of the relay sockets only when the starter is turning and the one that is supposed to read ground doesn't. Thanks again!

[SKperformance]

Are you sure the efi relay is working as well?

I think the alarm is messed up and the wire either disconnected or grounded out which is causing the fuel pump not to engage.

You should be able to hear the pump from the drivers seat just by turning the key to on.

[Ross W.]

There's got to be an impact switch that's activated. I'm not 100% positive on if or where it would be in an LS, but you describe exactly the way they sometimes are set off. Every Italian car I've owned had one, and sometimes they'd go off from a hard bump or a bumper tap. The impact switches in the cars I had killed the fuel pump and ignition. The dealer should be able to provide you with reset info, otherwise the chassis electrical diagram should show at least the location. Perhaps a body shop would have that info? I'm absolutely sure that's why your car won't start.

[CRLS400]

There's got to be an impact switch that's activated. I'm not 100% positive on if or where it would be in an LS, but you describe exactly the way they sometimes are set off. Every Italian car I've owned had one, and sometimes they'd go off from a hard bump or a bumper tap. The impact switches in the cars I had killed the fuel pump and ignition. The dealer should be able to provide you with reset info, otherwise the chassis electrical diagram should show at least the location. Perhaps a body shop would have that info? I'm absolutely sure that's why your car won't start.

Thanks again for the replies!

I was thinking the same thing (hoping) - that's why I asked about the fuel pump cut off switch first. I downloaded a doc that shows the location of every electrical component (there's hundreds) throughout the car so I'm about to read each one and see if there is any kind of impact/safety switch. I'll let you guys know.

By the way, at this point, the pump relay is not getting power with the key on - only with the key turned all the way to start and the motor turning...

[CRLS400]

Okay, I checked all the diagrams and there's no sort of impact switch... I removed the alarm and it made no difference so I removed the timing engine covers to get at the spark plug wires to check for spark and I found out that the timing belt was shredded! there was fuzz from it all under the timing proket covers. The belt wasn't broken but a lot of the teeth were worn off and it obviously had been slipping so I cut it and looked down and saw that one of the idler pulleys was broken. :( I had a pretty serious question before I went throught the trouble of replacing the timing belt. With the belt removed, can you turn the camshaft timing pulleys by hand to move the valves or does it take an extreme amount of force - I want to make sure the heads aren't shot before I begin..... Thanks!

[SKperformance]

I didn;t think there was any fuel pump cut off.

Should not be very hard to turn the cams.

Now you removed the alarm but did you disconnect all the relays that it came with and reattach them?

[sha4000]

yeah it shouldnt be hard to turn the cam and i dont believe the LS has a fuel pump cutoff swtch

[CRLS400]

yeah it shouldnt be hard to turn the cam and i dont believe the LS has a fuel pump cutoff swtch

Hey all - I started another post about the cams and the consensus is that it IS hard to turn them b/c you are overcoming all the spring pressure. I'm going to begin dismantling her tomorrow and I'll update my process on the other post. BTW I found out that I had power to both coils with the ignition on so the only thing not working was the fuel pump. However when I jumped the two terminals (FP and +B) on the check connector the fuel pump ran and pumped pressure. Do you think it's the EFI ECU? Thanks again.

[Threadcutter]

CR:

The belt wasn't broken but a lot of the teeth were worn off and it obviously had been slipping so I cut it and looked down and saw that one of the idler pulleys was broken.

OK, so by now it should be evident why it won't start. Hint; Valve timing is in need of a "little adjustment".

With the belt removed, can you turn the camshaft timing pulleys by hand to move the valves or does it take an extreme amount of force.

You might be able to by hand, but if you try, wear a good pair of leather work gloves. When the cam rotates, some of the lobes go over TDC & the spring pressure will cause the cam to spin out of your hands. Ouch! if you try it barehanded!

I'd suggest using a breaker bar (non-ratcheting, ratchet, if you know what I mean...........) with the correct size socket to turn the camshaft. It won't "get away" from you that way.

I want to make sure the heads aren't shot before I begin.

Your engine is non-interference, no worries...........

I would suggest that when you replace the timing belt (but before you "button" everything back up), you remove all the spark plugs, install your compression tester in each cylinder, one at a time, & rotate the crankshaft with a large ratchet wrench/socket. You won't be fighting compression in 7 other cylinders & you won't have a piston go over TDC & get away from you because of compression. Your compression should be very consistant through all 8 cylinders. If you don't get compression in one or more cylinders, there's no point in buttoning it up. That's highly unlikely though.