Fantius

My 1992 SC400 has developed an annoying problem. Here is everything I know about it:

1. The car cranks up with no problem, but will only run for a few seconds, no matter how much gas I give it.
2. The problem does not occur all the time. It seems to be worse in hot weather.
3. If I am unable to get it up and running, all I have to do is wait 5-10 minutes and try it again, then it will start up fine and keep running. So far, this has ALWAYS been the case.
4. Once it is started and running for more than 5 seconds, it will run indefinitely without any symptoms (not even a 'check engine' light).
5. If I have been running it for a while and stop it and attemp to immediately start it back up, it may or may not start (if it does not, see #3).
6. It is not the fuel pump (I just replaced it, thinking it was the problem -- so let me know if you want to buy a used fuel pump that probably works great).

BLK13X

Sounds like the fuel pump ECU (not the fuel pump). Usually these things go as the car ages.

Do a search and you should find some info on how to bridge the fuel pump ECU to run on 12v instead of the normal (I think it's 9v?), because I can't remember which terminals to bridge

BUT I'm pretty sure that the problem is the fuel pump ECU.


Jose

Fantius

Why should I bridge it to 12v instead of 9v? What does that accomplish? Do you mean so that a replacement fuel pump ECU will work or something? Thanks for the reply.

Fantius

After doing some research (should have done it before my last post), I see what you mean. But isn't that just a temprary solution? From what I've read, it sounds like that is a way to verify that the Fuel Pump ECU is in fact the problem, but leaving the bypass in indefinately could harm the fuel pump? I'd rather not pay $250 or whatever for a new fp ecu. But I'd also rather not ruin my brand new fuel pump.

JspecSC3

iTrader: (4)

Sounds like something my car was doing a while back. I think someone had called it missfire at startup. I just replaced my car's battery and everything was great. Turned out that my battery's core was almost dead due to its old age. Not enough cranking AMPs to start the car strong. So yeah, might just want to check that.

Fantius

There is absolutely no problem with cranking it. It always cranks. It just doesn't run for very long. I can rev the engine way up and it still dies slowly after a few seconds.

Fantius

Okay, I've got the part number but I'm having a hard time finding somewhere to buy it from. Google returns nothing useful. And the local Lexus dealer wants $330 or something.

Part number 89570-24010

I see now that this is a common problem, so who is selling these things?

Cloud9

iTrader: (2)

I just bought one for $45 shipped:

https://www.clublexus.com/forums/sho...d.php?t=159441


There are threads on the boards on how to install it.

https://www.clublexus.com/forums/sho...light=stalling

SoarinSC

I too am experiencing a similar problem. whenever my car is warm I sometimes have trouble starting it, after a couple of minutes it'll start with no problems. could this be the same thing?

London Bill

Yes it could (amongst other things) be the Fuel ECU preventing a warm restart, here s clip from my site about it;

ECU Symptoms:

The car failing to start when warm is normally the first indication that the fuel pump ECU is playing up, some time afterwards it might exhibit other faults, misfire under load (fuel starvation), starting up and then dying, this can be quickly checked out using the routine below. A replacement ECU is about £180 +vat, I managed to get a secondhand one for £70 from a breaker and it is working fine. The ECU is located behind the passenger rear side panel (the arm rest bit), take out the rear seats and side panel, the ECU is bolted to the frame, (15 minute job).

If you want to read the rest of it go here and look in Electrical/Fuel ECU SOarerTT

dwebb99

iTrader: (17)

Had same symptoms on my 92 sc 300(190,000 miles). Found a Fuel Pump ECU from my local junk yard for $40. (drove me nuts trying to fiqure out problem but this forum helped pinpoint problem)(dealer wants $325!!!yikes) Very easy to change out (below passenger window driver side 15 miniutes)and works like a charm. Alot of people seem to be having this problem and dealers are making A TON of money changing out everything BUT this part trying to fix this problem. Be smart, track down used part and change yourself.