[neondoctors]

Hi, I am completely new to dsm.

I found a 91 eclipse fwd non turbo automatic 2.0 l dohc.

The car had been sitting for maybe a year with a bad tranny.

The car seems to be whole and in good shape. It does not appear to have been tampered with in any way.

After some new gas and oil the car started ran ok then died about 2 minutes later.

Now you can start the car by pumping the pedal and as long as the key is still in the start position you can even rev it up but as soon as you release the key it dies.

The problem seems to be getting progressivly worse as it becomes harder and harder to start.

I am thinking maybe the cat is clogged?

Do any of you have suggestions or know of a similar problem before I start ripping pieces off?

Thanks in advance

 

[colonelfox]

Maybe I'm not following you post properly, but I'll try to help. When the key is in the "start" position the starter is engaging the flywheel and turning it and the engine's rotating assembly. This is building compression in the cylinders which is necessary to start an internal combustion engine. If the engine is running when you're doing that, you're destroying the starters and the teeth on the flywheel. I'd suggest you don't hold the key in the start position.
There's a few things that generally keep a car from starting. Start with the basics. Make sure you're getting fuel to the fuel rail. Make sure you're getting spark. Check the ECU to make sure the caps haven't leaked. We get several posts a week with starting problems, so try a search for "car wont' start" or something along those lines. Every answer you need should pop up.

 

[neondoctors]

Yes that is exactly what I mean. The car will RUN with the key in the START position. I realize that doing this is not a good thing but I also needed to show that the car does RUN under certian circumstances. IE the ecu fuel rail and other things appear to function when the car is in the start position but perhaps not in the run position.

I have done the search and can not find a problem like mine and that is why I was hoping I was just stupid and missed something.

I guess the way I see it either the car cant breath and the starter is keeping the engine turning or there is something missing in the RUN signal to keep the motor spinning. I am just not smart enough to fugure out which one is true and I hope someone who has heard of this problem will lend a hand.

Thanks

 

[neondoctors]

I removed the exaust pipe from the manifold and that has not helped the situation any at all.

Do any of you have an idea for the next step to troubleshoot this out?

thanks

 

[greenstreak]

This is a complete shot in the dark but perhaps look into the actual ignition switch itself. I am thinking that the electrical signal is lost when the key falls back to the run position.

 

[colonelfox]

I think Erik is onto something. Does the car actually run when the key is on start, or just sputter and sort of run?

 

[stevep]

Check the fuel pump circuit. The pump gets power while the ignition is in START but it's up to the ECU and the MPI relay to keep giving the pump power once you releace the ignition switch to RUN.

Steve

 

[neondoctors]

fuel pump control

Thank you for the replys....

I bought the haynes manual and it says to remove the fuel filler cap and listen for the fuel pump.

The fuel pump makes no noise in the start position so I crawled under the back of the car to make sure... still no whirring sounds.

Had them try to start the car and in the START position the fuel pump whirrrs to life and the car tries to start. As soon as they release the key the fuel pump drops out.

Soooo where do I go from here? What controls the fuel pump?

Thanks again for all the help!

 

[stevep]

The MPI relay has two inputs. One is from the ignition switch (after it winds through all the interlocks), the second from the ECU.
You need the wiring diagram for your car to track down what's failing. I can make a pdf of the diagram from my Backup Manual on CD but if your going to maintain your car you should think about getting one. http://www.manualcd.com/ Email me if you can read pdf and need it.

Steve

 

[neondoctors]

more stuff

The mpi relay, the one under the radio only clicks when the car is being started...

then shuts off when the key is placed to run

 

[stevep]

Pin 9 on the MPI relay comes from the ignition and interlocks. Pin 6 is ground for that coil. Pin 7 is from the ECU to enable the pump. Pin 3 is power for both the ECU coil (the other side of pin 7) and the pump. Pin 2 is the output of the relay to the fuel pump switched from pin 3.

So pin 7 should be pulled to ground by the ECU to keep the pump running. There should be resistance between 3 and 7 like there is between 9 and 6 if the coil is good.

There isn't anything other than wire between the ECU pin 56 and MPI relay pin 7. If it's not being pulled low then you need to check the wire, then the ECU.

Steve

 

[neondoctors]

Thank you steve for all the excellent advice

You have been a life saver...

 

[neondoctors]

It is storming here now so I really cant do much but I did try the little fuel pump by pass connector behind the battery and the fuel pump still did not start.

I will try to get voltages from the mpi and ecu tomorrow...

Thanks again steve

 

[stevep]

That's interesting. I've heard of that happening but my car (like some '91's) doesn't have a fuel pump check connector in the engine bay, only the connectors for the tach (found where the FP check connector should have been) and setting the timing. The connector, if present, should just be a tap into the line between pin 2 on the MPI relay and the fuel pump power feed. Connecting 12v to it should spin the pump up.

Since the pump does run in START mode there must be power at pin 3. Pin 8 would get power from the ignition switch to energise on of the two coils and close the contact from pin 3 to pin 2 to provide power to the pump.

I'm assuming that the ECU does work somewhat since the engine continues to run in START mode but either it isn't pulling pin 7 low to keep the pump running or the coil between pin 3 and pin 7 is bad and won't keep the contact closed.

Like I said, I'd first measure the resistance of the two coils to see if 3-7 went open. Then I'd try grounding 7 manually to see if the pump runs.
I'd also check to make sure power stays on at pin 3 when the ignition switch is in RUN.

Steve

 

[neondoctors]

IT STARTS

I am posting this final so that people like me who are dumb have a shot

Stevep was right on the money.

The ecu was not pulling in the contacts for the mpi. Well unless the contacts would pull in with less than 4 volts anyhow.

I went to the junk yard and picked up a ecu from a 92 talon with a 5 speed... mine is a 91 automatic.... and just in case to got the mpi relay too.

I tried the mpi relay ~less bolts to remove~ Even tho I didnt think it would work.. It didnt.

I replaced the ecu and the car fired right off. Died.. fired up again with a slightly high idle and continues to run.

I could not have gotten this far without the help of the wonderful, great and ALL POWERFUL ~falling to my knees and doing the waynes world were not worthy thing~ SteveP. I can tell you how appricative I am that he took his time to help out a newbie like me.

Thanks everyone that took the time to read this and I hope it helps someone else solve their problem.

 

[stevep]

Blush

Your welcome, I'm glad I could help.

Open up the old ECU and replace the caps. The odds are good their shot and that might just be all that's wrong with it. It never hurts to have a spare.

Steve

 

[neondoctors]

I have a friend that fixes vcrs and he thinks you are right, just replace the caps and I might have 2 of em.

Thanks again ... You have been great!!!

 

[stevep]

Tell your friend to look at this http://www.tmo.com/howto/ecu1g/caps.htm
It will tell him which one usually go bad. Don't forget to clean the board completely before putting the new caps in or the old electrolyte will eat the traces up.

Steve