92 LS 400 cruising at 65 & died ?

[bobirw]

Just died, starter turns it over one or times and it fires but no more. Acts like it's out of gas but is full. Where do I start? Any help appreciated. Bob

 

[stevechumo]

Just died, starter turns it over one or times and it fires but no more. Acts like it's out of gas but is full. Where do I start? Any help appreciated. Bob

When you crank, how does the engine sound like? Does it sound strong when trying to start? Is there any fuel or burning smell? You may check all fuses first, main and kick panel fuses. Any check engine? It may be fuel, spark, and electrical problem. It takes several steps to find out.

 

[bobirw]

When cranking it sounds strong. No smells, nothing different and now will fire and run for about one second but dies as if it is not getting any fuel. When the key switch is turned on, would there be any sound from the fuel pump because there is not any sound from anything until the starter engages. Also, how far can this car be pulled in neutral. Sorry for so many questions but really in the dark here. Thanks in advance. Bob

 

[Zuffen]

When the starter engages it switches the fuel pump to high speed (high output) and once it disengages it drops fuel pump spped to the low setting unles the engine is calling for more fuel.

I would think the Fuel Pump Control Unit ( I suspect you have an SC400) could have died.

You could try "hotwiring" the fuel pump to have it on high speed all the time to see if it will run.

 

[bobirw]

LS 400.. I located the Fuel Pump Control Unit. Now need to figure out how to hotwire the pump so it is on high speed. If it runs then thats the problem. Anyone familar w/ this hotwiring please drop a hint. Would be a timesaver for me and much appreciated. Thanks again . Bob

 

[spf_lexus]

I am having issues with what I assume is my fuel pump too. Mine runs/starts fine but it's ball-less after 2000rpm at part throttle, great performance if I floor it but if I just wanna cruise over 2000rpm, it isn't happening. It feels like the car "slams" as if the fuel is being cutoff. It feels like the TRAC engages and "slams" to cut fuel but I always have mine off. I have a new fuel pump but havent decided if thats my issue. I think I damaged mine from over-working via supercharger.

-the LS fuel pump is increased/decreased based on it's voltage. More voltage=more fuel and less voltage=less fuel. I would try popping out the fuel pump relay and just wire up igition and ground. I don't have the wiring specs of the relay but doing it correctly like Zuffen said would "force" the pump to max out at startup. Your idle may get a little crazy once the car is running tho...

 

[stevechumo]

If you test out the fuel pump, don't run it dry because it can be damaged. Most liquid pumps will burn if there's no liquid run through it. Perhaps you can have the emergency fuel tank (the red plastic 1 or 2 gallons) and have the fuel pump to it, while the pump inlet is in the car tank.

It could be the fuel pressure regulator, too. My desktop computer has the manual repair on it, but it's in the repair process so I can't help much with specific details.

 

[bobirw]

Well, I just got back on this project & don't know if I continue on this thread or start new one. I replaced the inline filter & wasn't the problem. I pulled the fuel pump relay out, just small plastic box connects with 4 prongs. Does anyone know how to check if it's ok or where I could go to find the procedure? Thanks, Bob

 

[spf_lexus]

I know the fuel pump relay doesn't go out... hardly ever. Mine was acting up and it was just dirty, wd40 + rag and issue went away but thats not too common.

 

[bobirw]

I tried the wd40, rag cleanup & no change. The fuel relay has 4 prongs which enter the 4 female prongs to reconnect. Which 2 of these 4 female connecters do I wire direct to fully activate the fuel pumps max pressure so I can hear it, start the car or whatever to find out whether or not the fuel pump works. Can any one tell me or direct me to a site with this onfo? Thanks again, Bob

 

[gloverman]

To run the fuel pump all the time bridge the Fp and B+ terminals in the diagnostic box under the bonnet. Then check there is voltage at the large terminals on the fuel tank. You also need to check for spark. If one of your coils fails the ECU will not receive the feedback signal from the ignitors and will turn the injectors off. If it is a failed fuel pump then the engine will start when you manually feed engine start into the intake(use the powersteer idle up hose on the front). To check spark remove number 5 and 7 leads (LH side rear) and earth some spare spark plugs onto the manifold and crank. Both should have strong spark when cranking. Just a few suggestions - cheers