Hey guys, I picked up my sc300 about 6 months ago and she ran fine up until December, specifically NYE. I was driving on the freeway going to go party it up and the car just shut off on me. I was in cruise control and all of a sudden the gas pedal wouldn't work. I coasted to a stop and tried to figure out what was wrong. After about a minute, I took out the keys and put them back in the ignition and she fired up just fine again. It was VERY weird.

Fast forward a few weeks and she would do it again randomly. The car would just die when I was cruising on the freeway or street. I'd have to pull over, take out the keys, and restart it. However last night, the car just would NOT turn over at all. I was sitting on the freeway shoulder trying to get it to fire up. I got her to fire up a couple of times but it would idle at 100rpm and immediately die out. I called AAA and they towed it back to my house. When I got home, the car started up fine and idled perfectly. I absolutely have NO IDEA why the hell my car is acting up.

I did change out the spark plugs about 3-4 months ago and made sure they were gapped perfectly. I changed out the air filter and cleaned out the airbox too. I also changed out the fuel pump in the middle of all this for a walbro unit so I'm pretty sure its not the fuel pump.

What do you guys think??

 

Ok I came back to check on the car and it seems to have trouble starting again. I can start it for a bit and drive it for 2 feet and it shuts off. Took me a long time to move the car. I'm lost. Anyone got any clues?

 

Fuel pump ECU I'd say. I had this happen to my SC300, as well as a friends.

Search for jumping the Fuel Pump ECU using the diagnostics port under the hood. I'll look for it now and post the thing you should try. If it never does it again, it means the ECU is messed up.

 

Ahh duh, it was in an old post of mine in 2007 when I had this same problem!

You need to open up the diagnostics port under the hood and jump the Fp and +b. If this works, then you have a faulty fuel pump ECU (at the very least).

Good luck!

 

This happend to me.

the EXACT same things, in fact.

Fuel pump ECU.

do the 12v mod.
Search for it on this forum, read, perform, done.

 

See if the fuel pump ecu has gone out. Also check your MAF unplug it and see if the idle stays in the correct range in the 800 area. Do you have any check engine lights on? If the fuel pump ecu is going out there should be a code for it same thing if it was a MAF issue.

 

I have same issue with my SC300...

Here is what I did so far...

When I first had this problem... I did 12V mod.... good for about 3 months...

again, I had same problem... changed fuel relays... fixed the problem for 2 weeks...

I had same problem... changed fuel pump... did not resolve my problem...

changed fuel pump ECU... still did not solve the problem...

ran code... got back with 71 / 78... 71 is o2 sensor... with I don't care anyway... and 78is fuel system...

I removed all the parts of back seats... and ended up towing it back to my place...

Any idea? I am thinking of reversing 12V mod.... please help...

 

I had a short in one of my O2 sensors and It would die right away, or even blow the EFI fuse. thats the second part of the problem. You should locate the faulty 02.

 

so I should be reversing 12 MOD...

 

I finally fixed it... undo my 12V mod...

 

I don't have the 12v mod done, but my car does the same thing. I've bought new Relays, replaced the EFI fuse, and got a new fuel pump ecu, and i'm running a walbro 255. I was thinking it could be the 5speed 92 ECU but now im thinking its something else.

I have a possible air leak after my MAF sensor, and I checked my cats recently, although I have no codes, i could of damaged or did something to the 02 sensor..im not sure.

Also, my fuel pump would not shut off after the car was running and i shut it off, and the relay seems to be getting power with the car off. No mods, no jumper from Fp to B+, and no idea why.

HELP ME!! i've had this problem FOREVER and it's seriously driving me mad, i need my car to run!!

 

pull ur code... did you replace Fuel Pump ECU?

that was my main problem...

 

He has no codes, and replaced the ECU.. its clearly stated up above.

You have some electrical gremlins to work out. When I smashed in my O2 sensor, it kept shorting out the EFI fuse. Sometimes he car would just die, and the fuse was fine. Check the O2 sensor and listen for leaks after the MAF.

 

Did your o2 sensor problem only occur when the car was warm? I'm guessing it threw a code as well?


My car has no codes, and when i power the fuel pump by jumping the terminals fp - B+, eventually it gets warm, idles really low and then dies on me.

 

i was having the same problem found out my neg cable was loose on my battery..