Fuel pump?

[a.Lpha]

Okay i think i remember reading something about this earlier on the forum, but can't remember.

Now that my wonderful car wich is just a money pit (obviously though it is old) anyways to get past the bitching...

i've recently changed the alt and the power steering pump and NOW have a new problem wich i think is the fuel pump. (it has also been getting colder and has only just recently dropped below 0C) the car can start no problem as in the starter turns the engine over, it sounds normal in that sence but then it just dies after the starter stops. it sounds jut like it's out of gas. are there other fixes first that i should look at or is the fuel pump my best bet.

 

[Peewee]

Fuel pump doesn't have to do much at start or idle.
If it runs out of fuel at full throttle, thats when you look at the pump.
If its having issues starting in very cold, then start with the cold start injector and time switch.
However I'm not sure if the 1994 LS400 runs this (they stopped using them around then, but it could have been 1995).

Failing that, next thing I'd try is replacing the caps in the ecu.

 

[a.Lpha]

I'll see if i can add a bit more, as unfortunately i was not driving when this problem happened. It was running fine and was driven down the highway for about 20min at 60m/h ish the person picked somebodey else up and it stalled in the driveway. it started again with some pumping from the gas and drove back down the highway and stalled at a stop sign and didn't start again. it sounds perfectly normal though when i try and start it just after again as i said before the starter stops turning the engine over it just stops again.

 

[Peewee]

Bridge FP and +B in the diagnostics box and try again.
You should hear fuel going through the fuel rail (with the key ON).

 

[a.Lpha]

Bridge FP and +B in the diagnostics box and try again.
You should hear fuel going through the fuel rail (with the key ON).

i want to make sure i do it rite is there a picture or anything that i could get of the diagnostics box and make sure?

 

[Peewee]

Its a small black plastic box on the engine with DIAGNOSTICS written on it.
Under the lid is a legend of what pins do what.
Assuming you aren't blind you can't go wrong.

 

[361UZ]

This is exactly what my 1uz was doing, except I traced it to the injectors - as the engine hadn't run for 10+ years, they were all gummed up.
BUT it is the same symptoms:it fires up OK, but stops within a few seconds ( at most).
I would be checking the 12 volts to the injectors. If you use a test light (a 12 volt bulb in a suitable holder) you should see a constant light on one terminal of each injector, and a pulsing light on the other as you crank the engine.

 

[a.Lpha]

Okay so this is a bit odd... i took it to my mechanic to do a double check for me and he said that the computer just needed to be reprogramed. (Asked if i had been having battery problems wich i had as i just replaced the alternator) He told me he just left the car in the on position but with out starting the engine for 10 min, and now it's running normally again. So, that's an inexpensive fix!

 

[a.Lpha]

I also changed the battery as the old one was starting to die (rated at 850CCA and was only giving 500 now)

 

[361UZ]

Okay so this is a bit odd... i took it to my mechanic to do a double check for me and he said that the computer just needed to be reprogramed. (Asked if i had been having battery problems wich i had as i just replaced the alternator) He told me he just left the car in the on position but with out starting the engine for 10 min, and now it's running normally again. So, that's an inexpensive fix!

Nice one.

I wonder how many "dead" computers are fixed this way, after the unsuspecting customer has paid for a new one... (Then the old one gets resold as "reconditioned"?)

 

[Peewee]

Did you try to restart it after you put the battery in, because removing the battery for more than a few minutes resets the ecu.

I'm not aware of having to leave the key ON to reset the ecu.