1G GSX starts everytime - but dies in 5-10 seconds...

[JohnnyPC1]

Hey fellas!

I'm somewhat new to this DSM scene. I have a 91 GSX that will start everytime but then dies after about 5 - 10 seconds. So far I have replaced the fuel pump, ISC motor, fixed a idle control switch to close when the throttle is shut and replaced the capacitors in the the ECM. Still the same trouble...drats!

The car will start everytime and seem like everything is OK but then dies. If I step on the throttle it has little or no effect on keeping the engine running...even if I rev it to 3000 rpms it will still die. I bought the car with the same symtoms so whatever I have done to date has had no positive effect...

What should I verify next since I'm kinda running out of things I know to check...I've scanned the FAQs and forums for similar troubles but none really jumped out at me

Thanks!

 

[JohnnyPC1]

That's what I was thinking too. The traces looks a little grungy and a through hole doesn't look the cleanest...I'll see about giving them a redo. So the capacitor leaks, corrodes some components and the ECU dies. Replacing what appears to be the bad components may spring it back to life? Or will the fact that these components being compromised lead to damaged circuitry elsewhere? Damage that might not be visible?

 

[steve]

The elecrolyte seeps under the coating and eats away at anything metal it can reach. I've found that it tends to attack the solder and the exposed copper around the ends of the solder mask sometimes just enough to seperate the trace from the pad but sometimes it will eat the pad off the board, like you found. If you don't clean off all the contaminated conformal coating and neutralize the electrolyte it will continue to eat away at things in the future.

Any part that the solder joints have turned black should be inspected for damage or opened traces. So far all the ECU's I've worked on that just had corrosion problems have been recoverable as long as I could replace the damaged parts and repair the bad traces.
The only source for most of the IC's are other ECU's so replacing them can get expensive.

Steve

 

[JohnnyPC1]

Well I spent some quality time with the circuit board today. I soldered in a replacement for c37 (.1uf) and created some alternate routes for traces that looked corrupt. Also stuck wires through a couple through holes that looked yucky. Plugged it up to the car and same issue - starts but stalls within seconds...damn! Thought I could salvage the unit but no go. At least I recreated the problem after swapping in a known good ECU.

Anybody want to sell me an ECU for a 91 GSX?

Cheers!

 

[steve]

Did you get your ECU today?

Steve

 

[JohnnyPC1]

Sure did Steve! Haven't had a chance to even open the package yet - I'll see about getting it re-installed Tuesday.

Anybody in the market for the '90 ECU I was using while this electronics ace repaired mine? Worked perfect in my '91 GSX after modding the 6 and 14 wires on my harness. Even the tach worked - I thought that wouldn't work per topics in the FAQs...

 

[ITSME4G63]

Mine did that, Checked the ecu and the capacitors leaked, caused the fuel pump to turn off, check your ecu.

 

[JohnnyPC1]

Yep! That's what did the trick for me. Except the caps alone wouldn't solve the problem - I replaced them and still had the same trouble. This Steve guy is pretty damn great at at understanding how to repair these things. I sent the unit off to him, he figured out he could fix it and 4 days later I had it back ready to go. Anybody falling into my same boat ought to drop him a line...

 

[steve]

Good, USPS said it would be there today and I wanted to make sure it didn't get lost.

From what I dug up this weekend, I have a better understanding of the differences between
the 89-90 and 91-94 as it relates to the ignition and tach. The tach signal is not generated by the ECU, it comes from the coil pack on an early 1G or the power transistor module on the later. From the circuit diagrams it looks like the early 1G uses a OR gate on the two coil lines from the power transistors where the later used a NOR gate. I haven't sat down and figured out exactly how that changes the nature of the tach signal but since what the tach is looking for didn't change by switching the ECU I'm not suprised it worked.

Steve

 

[steve]

, I fixed ITSME4G63 ECU too for the same problem, different cause but the same symptom.

Steve

 

[ITSME4G63]

, I fixed ITSME4G63 ECU too for the same problem, different cause but the same symptom.

Steve

Sure did, and works works great now

 

[GSX503]

I have a 2g, but last week I was in pheonix and my car was doing the same thing. It would start every time, run for a few seconds and then die immediately. The check engine light was on. I had to bring it to a shop, they put the scanner on it: Cam position sensor. Replaced that and it runs perfect again.

I'm new to these cars, but I thought I might be able to help here...

Hey im having the same problem. But I replaced the cam position sensor the problem is still there. I plug the OB2 and reads cam position sensor or cam position in PCM. Car starts up idles for 1 to 2 seconds then dies. I've got so piss so I gave it a rev to 4k rpm and now the car wouldn't start. The car trys to spark does not turn over.

 

[GSX503]

Welp! I think it's mission accomplished I tested the known good ECU from my other GSX (auto) in the stalling car and it appears to run fine. At least the issue I was having has abruptly disappeared. I'm going to put the old ECU back in to see if I can re-create the problem I was having but I'll do that this weekend.

I guess the capacitors I replaced in the stalling ECU weren't all that was wrong with it. Looking closer, I found that there's a capacitor (c106) that just fell right off when I nudged it a bit. Some traces are grungy too. I'm going to replace that cap and see if I can resurrect this ECU - anybody know the value of the c106 capacitor?

Also, I haven't run the thing all day long or really beat on it with the auto ECU in it, but it does seem to run properly. Anybody have more input on using an auto ECU in a manual equipped car? I have my stuff for a datalogger cable coming later this week so I'll get to see some actual numbers of what's going on. I do get a check engine light that comes on occasionally when I coast to a stop but other than that, car runs well...

Cheers!

I was reading thru the forums looking for the same way you were before, also i'm in the same boat. I plug in a OBD2 and reads cam sensor position or at PCM malfunction. One day I've got piss and rev it to 4k rpm and now the car wouldn't turn over. I changed the cam position sensor and it wasn't the problem so i checked the volts to the that sensor harness and it came back with no volts. I tried just about as much as you did but not the ECU. Question is the ECU and PCM the same thing? After I kept trying to start it so much, I also flooded my motor, but I took out the spark plugs and the first one was filled with oil.
I've cleaned them and still not turning over. The plugs are new only a few weeks old.

 

[mitsutuner]

since it won't start, Pull out any spark plug & see if it's wet with gas.
You are lucky if it is dry & the problem gets fixed with a new fuel filter.
If the car runs a few seconds then dies, won't restart right away, but after awhile it will restart & run a little then die--consider an almost completely clogged fuel filter that won't allow enuf gas to pass to run the car---yet after sitting, enuf gas slowly passes thru the filter to allow you to restart,
(because the fuel in the line from the pump is still under pressure after the motor stops.)

 

[92tsifwd]

Mine is doing the exact same thing exept it does not do it all the time. It keeps throwing a knock sencer code. I replaced all 3 capacitors and it still dies only it is doing it more often now. I think it might be a bad cam angle sencer because a guy on tuners not to long ago had that problem and had a cel (knock sencer) come up even though it was the cas. I don't know what the simptoms were though. I still hear the click everytime (coming from ecu) right before it dies and when it decides it wants to idle I hear backfires and pops like a mother and smell gas. I know it is running rich possibly due to the timing. The only other thing I can think of is the ecu itself or the knock senser but most people's cars dont die from bad k-sencers do they? Any help is greatly appriciated!

 

[92tsifwd]

The car drives perfect at night and only acts up when it is moist or hot out and the fact that it starts up every time leads me to believe that it is vaper locking. I know, it sounds stupid but, my fuel pump cover has never sealed sence the new fuel pump went in. Anybody that is experienced with fuel press tell me how this effects the fuel press.
Thanks!

 

[mitsutuner]

100% gauranteed, have your ECU professionally rebuilt & your car will run correctly. Sooner or later you WILL arrive at that conclusion for your problem, if you continue to drive the car like it is, you WILL destroy your ECU to the point where it will have no core value, adding $200 to your repair cost.
Every click you hear before the motor dies, fries your ECU printed circuit board a little bit more.

 

[92tsifwd]

100% gauranteed, have your ECU professionally rebuilt & your car will run correctly. Sooner or later you WILL arrive at that conclusion for your problem, if you continue to drive the car like it is, you WILL destroy your ECU to the point where it will have no core value, adding $200 to your repair cost.
Every click you hear before the motor dies, fries your ECU printed circuit board a little bit more.

The car drove perfect last night for the most part and never died once. It only dies when it is moist or warm outside. The fuel pump cover does not seal and there is water in the gas so, I am going to fix that first and go from there and the fuel filter could be clogged also due to water getting in the gas. The cel is on regardless of it running or not but, I believe that it is a bad sencer. Not shure why it clicks right before it dies though? If this does not work I will send my ecu off somewhere to have it checked.

 

[92tsifwd]

I have sealed the fuel pump and it still dies. I did not even make it out of the drive way before it died. I will explain exactly what the car does from the begining.

I start the car up, In 10 seconds the cel kicks on. During this time I hear miss fires poping sounds from the exhaust. I let it warm up and put it into reverse and at the end of the drive way I hear one click from ecu then it died and after that it starts up every time and then dies after 2 seconds. Sometimes it will die amedeitly after you start it and sometimes I can drive around a whole night without it dieing but, cel is always on. I think it is the ecu. Who can check it and possibly fix it? Also plugs are Bpr7es ngks and they are dark colored almost black. I need to know who can check and repair my ecu?
Thanks!

 

[92tsifwd]

Bad ECU in my case.