1G Fuel pump stops working occasionally

[Otto]

Yesterday my car went off while driving on the highway. Had to pull over and start scratching my head. It's the third time my car has done this to me. Previous two times I got it started after waiting about an half an hour and several cranks. But this time it didn't work. I got a friend of mine to tow me to a nearby parking lot where my car is atm. We inspected it there and noticed that the fuel pressure wasn't rising while cranking.

I've changed my fuel pump about 5k miles ago to a non-OEM replacement pump. Fuel filter was replaced at the same time. I kinda doubt that it'd be the pump, because last two times this happened it eventually wasn't it's fault. The wiring can't be all bad either because the car would most likely start now if I went there and cranked.

I read in a thread here that the ecu won't let fuel be pumped if it gets no signal from the CAS. Is this true? Could this problem be caused by for example leaky caps or a bad CAS? A bad CAS would most likely cause a terrible amount of other problems too, wouldn't it? I also read that someones fuel feed problem was solved by a rewiring mod. What's that and would it possibly help me?

One common factor with these three times my car failed this way is that the temperature has been very warm (which means about 80-85F in here). But no signs of overheating though. In dash temp gauge shows the normal reading.

This is very annoying. So please, if you have any ideas I'd be glad to hear them.

TIA.


PS. My car is a n/a '92 EDM, which is similar to your 1Ga. Almost everything is factory default. No bigger injectors, pumps or anything.

 

[psiaddict]

Well, just an opinion here, but if money were not the concern, I would definitely be leaning toward the Evo X. I love DSM's myself, but the only advantage to starting with the older platform is lower cost of entry and the "old-school charm"!

The Evo platform has been improved beyond the DSM as far as handling and chassis performance. In addition there will continue to be performance upgrade options coming out for the Evo for years to come so you will not be limited in any way no matter how you want to build up the car...and on top of that you will have a newer vehicle to drive while you are building it up.

As far as the Fuel pump stopping, one question I would have is if the pump is stopping due to overheating...not the car, the pump. Since it usually starts again later, the pump would have cooled down again and is no longer locking up for instance. I have heard of contamination getting into the Fuel pump and causing it to lock up also.

I agree that the wiring is less likely since you did not touch it between no-start and start conditions but on the other hand, I have had faulty ground do some strange things to me if they are loose or contaminated.

I have not heard about the CAS signal not allowing the Pump to run... but it may be true.

 

[Otto]

As far as the Fuel pump stopping, one question I would have is if the pump is stopping due to overheating...not the car, the pump. Since it usually starts again later, the pump would have cooled down again and is no longer locking up for instance. I have heard of contamination getting into the Fuel pump and causing it to lock up also.

Does anyone else think this makes sense? Overheating of the pump would be a reasonable explanation, but is it possible? At the time of failure my fuel gauge indicated about one sixth of a tank of fuel. Would the fumes inside the tank be hot enough to jam the pump? Ofcourse the pump generates some heat by itself, but still...

And when it comes to the contaminations, as far as I recall there was a tea-bag-like filter on the bottom of the filter which is meant to prevent junk from getting through the pump.

 

[steve]

Since the car doesn't start right now you should be able to identify the cause. Treat this just like a typical no-start problem, check the ECU then look for compression, fuel and spark. Don't assume anything upfront.

If you don't have a datalogger, it might be time to make one.

 

[Otto]

Since the car doesn't start right now you should be able to identify the cause.

Problem is that the car does start now.

I have a DIY logger cable which I've been using with Tunerstein. But haven't been able to use the logger since I changed to laptop without a serial port. I even bought one of those USB <-> RS232 adapters, but it didn't for some reason work.

One thing I could add here is that I didn't get a CE-light at all.

 

[steve]

Problem is that the car does start now.

Yesterday my car went off while driving on the highway. Had to pull over and start scratching my head. It's the third time my car has done this to me. Previous two times I got it started after waiting about an half an hour and several cranks. But this time it didn't work. I got a friend of mine to tow me to a nearby parking lot where my car is atm. We inspected it there and noticed that the fuel pressure wasn't rising while cranking.

Sorry, I'm easily confused. Since you said you had to tow the car I got the impression is wasn't running.

I have a DIY logger cable which I've been using with Tunerstein. But haven't been able to use the logger since I changed to laptop without a serial port. I even bought one of those USB <-> RS232 adapters, but it didn't for some reason work.

One thing I could add here is that I didn't get a CE-light at all.

1G's use a non-standard bit rate that few USB to serial adapter beside those based on FDDI chips support, like the Keyspan everyone uses.

If your CEL bulb works, it not turning on for five seconds when you turn the ignition on is a indication that the ECU didn't power up and isn't running.

That will keep the engine from running but not the fuel pump from pumping when your cranking the engine. That's independent of the ECU, it only keeps the fuel pump running after the engine starts and you stop using the starter (while it sees CAS pulses) or turns it off a few seconds after it stops seeing CAS pulses.

Random dieing and being able to restart the car after some delay was one of the early symptoms of capacitor leakage in the ECU.

 

[Otto]

If your CEL bulb works, it not turning on for five seconds when you turn the ignition on is a indication that the ECU didn't power up and isn't running.

Bulb works. It lights up for a few seconds after turning key to ACC.

Random dieing and being able to restart the car after some delay was one of the early symptoms of capacitor leakage in the ECU.

Could this be fixed by changing the caps? Or does this basically mean that the whole ECU is wasted? I'm experienced with electronics and soldering. I've been modding game consoles and built guitar effects, so technically it's not a problem for me.

 

[steve]

Take it out and check it. If it is leaking the extent can vary greatly. If it's not and still has original capacitors replace them before they do leak.

 

[spydergotboost]

impossible to diagnose a car that isnt showing the symptoms. have to carry tools with you until it acts up again and diagnose it then.

 

[Otto]

I took the ECU out and here's what I found out...

Apparently the caps have been changed by a shop back in 2005. There were no factory seals but instead it was sealed by time stamped stickers of a german shop. The caps are of higher voltage than the original ones and they seem to be ok externally. But the circuit board underneath them seem to have taken a little damage most likely from the previous caps electrolyte. A couple of copper traces seem to have been replaced with jump wires or solder. Nevertheless the rebuild quality looks good. Do you think it'd be worth trying to fix this by changing the caps?

In case I decided to get a new one, does the MD number have to the same? Or is it enough if it's take from a similar car with same engine, tranny etc? My box has the number MD169144 on it, while the ones dsmgraveyard sells has got a different number. Will those work even though they go by a different number? Dsmgraveyard has those listed for $65, but they seem to be out of stock atm. Where else could I look for a replacement? Perhaps eBay? What are the odds to receive an actually working ECU from there?

Eventually I'm looking for the cheapest way to get away with this.

PS. Is there a schematic of the ECU?

 

[steve]

PS. Is there a schematic of the ECU?

No schematics, the best you can do is what little is in the FSM and work backward from there.

 

[debbie]

I had a similar problem on a car I had, it turned out to be faulty fuel pump relay. It would over heat and cut off the fuel pump. Apparently it was kind of like a safety thing and was acting like there was a fire in the engine bay and it would stop the fuel pump pumping fuel into the engine.
It would happen at any time and i would take like 5 to 10mins to start the engine once it had stopped.

 

[Otto]

I had a similar problem on a car I had, it turned out to be faulty fuel pump relay. It would over heat and cut off the fuel pump. Apparently it was kind of like a safety thing and was acting like there was a fire in the engine bay and it would stop the fuel pump pumping fuel into the engine.

Are you talking about the MPI relay under the radio? The one that clicks quite loud in a couple of seconds after shutting down?

It would happen at any time and i would take like 5 to 10mins to start the engine once it had stopped.

The time between the stall at the highway and getting towed to the parking lot was more than an hour. That wasn't enough time to recover. The next morning it did start though.

 

[debbie]

This was on a different car all together. It is just a thought. If you could get ahold of one and try, you never know

 

[Otto]

I changed the caps and C44 which looked a little damaged. I also rewired some worn copper traces with jump wires. I found out that C44 is a 0,01uF ceramic capacitor. I didn't have those as surface mountable, so I replaced it with a normal two-legged ceramic cap. This shouldn't cause any problems.

To my surprise the car didn't start after plugging the ECU back in. I'll try again in the evening when the temperature has decreased... It's close to 85F outside and the car is in direct sunlingth :/

 

[Otto]

I diagnosed this problem further and found out that my fuel pump starts pumping only maybe every fifth time when connected directly to a battery. When it doesn't start it just says "gluck" and starts to heat up. We'll see what happens after I replace it.

 

[spydergotboost]

any update?