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 Post subject: 91 Dodge Colt GL dies
PostPosted: Mon Nov 12, 2012 9:06 pm 
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Location: Pittsfield, ME
I have a 1991 Dodge Colt GL with the 1.5l 4g15
it has a 5 speed transmission with 285k miles
it burns a little oil and runs great

it does have a problem though.
I can start it and run it for about 20 mins and then it just dies.
I expected the fuel pump because it only died when driving so tested the psi in the fuel lines and it was 35-40 at all times right up until it died. I didnt test the power to the fuel pump but if it has 35-40 psi then it must be working correctly.
I was also expecting the coolant temp sensor may be an issue if it dies when at idle without driving so I let the car idle until it died. Then I let the car cool down (outside temp 45 degrees) for 5 hours and then tried again and nothing.

There is no issue with air, no issue with spark, and i think the fuel system is good, so this issue has stumped me.

I don't know if there is a common issue with these cars or anything that would cause this, a sensor, or relay or something.
Any ideas or questions , this car runs great when it runs, I just want to put it back on the road.


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PostPosted: Mon Nov 12, 2012 9:22 pm 
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Is the check engine light on by chance?


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PostPosted: Mon Nov 12, 2012 9:23 pm 
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No it is not unfortunatley, I wish it was so I could scan it.


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PostPosted: Mon Nov 12, 2012 9:26 pm 
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When it "dies" can it be started again, or does it just crank without firing?


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PostPosted: Mon Nov 12, 2012 9:51 pm 
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It will just crank over and over, it also doesn't even give the appearance of catching ever. I ran it until it died 9.5 hours ago and I just tried to start it again and nothing. It will start tomorrow though as it always has.


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PostPosted: Mon Nov 12, 2012 10:03 pm 
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Just to clarify, now that it has "died", it still has spark and fuel pressure correct?


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PostPosted: Mon Nov 12, 2012 10:13 pm 
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If no spark at that point, suspect electrical issues.

Has the ECU been inspected for leaking capacitors?

Sorry to interject, I know we were all thinking along these lines, so I put it forward.

Now back to our regularly scheduled program.


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PostPosted: Mon Nov 12, 2012 10:18 pm 
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I am suspecting ECU, MPI relay or injector resistor pack (POSSIBLY, if the car even has a resistor pack), that funky little "power transistor pack" that the coil interacts with or something along those lines. What is strange, though, is pretty much all of these things would cause a no spark condition and/or a CEL. If the spark is weak then it could potentially be one of these items.

My current Colt had a weak spark condition but would not start, the resolution was to replace the coil.


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PostPosted: Mon Nov 12, 2012 10:40 pm 
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I was having driving issues with my first Colt 4g15 setup, and finally died at a stop light. Bought every manual know to man that was not OEM, traced all the wires with my little electrical know how at the time, and thought my coil was boink. Replaced the distributor, and nothing. Turns out the ECU was leaking heavily and not repairable even with new CAPS. Yes, this was a no spark condition unlike was is likely happening here, but it sounds like heat is a major factor and what is making it seem like the situation resets after a cool down. IF the ECU is not recapped already, we all agree it has to be regardless of where this situation leads us, but this will be a five minute ECU removal, and best he figures out where it is now. I totally get where you are going with this too Shaun, no worries.


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PostPosted: Tue Nov 13, 2012 7:37 am 
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Ecu

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PostPosted: Tue Nov 13, 2012 3:23 pm 
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Okay sorry I didn't get back on here last night. So from what I can tell is that you guys think its the ECU?

Some other theories I had (and correct me if I'm wrong) were:

*The Check Engine light is not on...

1. The Coolant Temp. Sensor: I was thinking that it runs for 20 mins, gets up to a certain temp and then kills the car. The car still has fuel pressure when its dead but I'm not sure about the spark. The only thing that makes me veer away from the temp sensor is today I started it this morning, got it up to temp and shut the car off. I tried to start it again and it started fine. The temp gauge displays normal temp as well.

2. The Fuel Pump: I thought that when car was started there was pressure in the lines and slowly as the car runs the fuel pressure goes down and kills the motor. When the motor died though it didn't sputter or anything just died like someone hit a kill switch. As well as when its running the car runs without stutter. So that made me veer away from the fuel pump.

3. The Thermostat: May cause the temp to be read wrong and tell the ECU the car is too hot. Again though the temp gauge still shows normal temp and if the thermostat was bad wouldn't it overheat and/or display incorrect temp on the gauge.

4. A relay (ignition, fuel pump, etc). There may be a short in a relay that after it heats up causes the car to die. I have never seen that happen and I have had about 40 cars but I have never had one of these cars.

5. ECU? Can you tell me why you guys think its the ECU. I would normally think that it could be the ECU but where it starts right up the next day like clockwork it leads me to believe its something that has to do with heat. The ECU if it stopped it wouldn't come back on, and if it did it wouldn't be so regimented in how it will only start the following day.

Sorry for the long wind on this, I just got the car for a good deal and need something to get to my Dr's appointments 1.5 hours away because I have a terminal illness and with gas at 3.75+ I will like the mileage and want to get this thing running smoothly.

Any other questions or ideas would be so helpful. Thank you for the help I really appreciate it I am beyond stumped on this one everything seems to contradict the other.


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PostPosted: Tue Nov 13, 2012 8:05 pm 
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If the coolant temperature sensor is bad the ECU will assume the coolant temp is -77*F. This does make the engine run rough, but does not keep it from running.

Mitsubishis of this vintage are known to have ECUs with leaking capacitors which damage the printed circuit board. This can create odd issues, but usually results in multiple CELs and/or a car that will not run at all.

To rull-out the ECU, simply remove the small vertical kick panel on the right side of the passenger foot well, remove the ECU from its place, open the ECU by removing the four phillips-head screws then inspect for burnt areas of the printed board, any "fishy" or "electrical" smells or obvious leakage onto the board.


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PostPosted: Tue Nov 13, 2012 8:09 pm 
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4g15's using EFI were/are very known to have the following weak points - distributor (which is mainly the coil we see fail) and ECU which can cause all kinds of gremlins.

CSM Shaun and I are poking at the ignition and related controls, the ECU.

We need to know the condition of spark when it won't start.

For reference, all the factory service manuals are located here: http://www.lilevo.com/mirage/ <-89-92 (4g15 mainly) and 89 Colt.Mirage Turbo (4g15/4g61t) are both located there and so are the specs if you are testing individual components.

So, when the ECU caps leak, which they WILL DO GUARANTEED (if never changed and acid damage stopped/repaired), is the acid will leak down the circuit board as the caps heat cycle and deposit a bad smelling and caustic chemical bath on the traces, chips, and whatever happens to get in it's way.
The ISC driver can be blown, the spark circuitry (as affected on my first car), and many more ghostly things can happen as a consequence.
There is an entire rebuilder industry focused on early Mitsu boards from 1989-1994ish time frame due to their capacitors being essentially defective. They were all made like this.
Now that you know a little history about what can go wrong, we would need a little input about the spark when the car does not start, and what the ECU looks like internally.
A spark tester can be setup readily on top of the motor and can probably be seen from the front seat as the motor cranks.
Next up, is removing the ECU from the right front kick panel. Remove trim, two 10mm bolts from the ground straps/case grounds, and find a way to dislodge the ECU pulling very sharply in a downward motion; be warned they are wedged in good and will have to back the same way!
The outside ECU case scews are very tight, so have a proper fitting phillips screwdriver and use your weight on them as you turn.
Once inside, you will find something like this:

GO HERE - http://vfaq.com/index-main.html
Select the DSM site
There are headings at the top - select ELECTRICAL
First post is Capacitor replacement - select and scroll down for pics.

Ha, Shaun and I just posted at the same time.


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PostPosted: Tue Nov 13, 2012 9:01 pm 
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It's okay, great minds think alike. Your post is more informative than mine. I tend to post exactly how I work on these odd issues which is one step at a time. For an experienced wrench, such as GLman, it is better to provide as much information as possible up front.


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PostPosted: Wed Nov 14, 2012 2:04 am 
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Another vote for the ECU. Open it up and take a whiff, if it smells a little fishy, take a close look at the capacitors.

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Had a:
1991 Eagle Summit ES Hatchback - 4g15 12v 5spd
1991 Dodge Colt -4g15 12v 4spd
Have a:
1978 Oldsmobile Cutlass - 468BBO TH350
Round 3:
1990 Dodge Colt-4G63T 5spd


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