1990 3.1 Euro having the 'stall when warm/will only crank, no start' issue

[JDMichel]

Good afternoon all:

I have been reading the AF forums for a number of years, but today decided to register as a member, as I am having the problem that seems to plague the 3.1L MPFI engine where it will sometimes turn over when cold, run for a short period of time (usually until it goes into closed loop) and then stall, not being able to start for a period of time after that. It's only been doing this for the past two weeks, although I've had the car since 1994, and it has pretty much run maintenance free since that time.

In the last couple weeks, I have changed out the three coil packs and ICM that the coils sit on, had all six injectors replaced last week, and although it ran great for the road test, after it was parked in the dealer lot and I went to pick it up, the ol' girl would crank over and not fire up. We had the mechanic that worked on it come out and check the fuel pressure (42 psi), spark (good), but for some reason it still would not fire and turn over. As a side note, the low coolant light has been on for a number of years, to which I have just monitored my coolant level. I cannot see any evidence of LIM gasket leaking or any coolant on the ground or in the oil either. Now that the injectors have been replaced, when it did fire up, it ran better than i can remember in recent years. For the longest time it would surge at idle after warming up and even though it sounded like it was going to stall out, it never did up until two weeks ago. There are little things that at the time I thought made a difference, like unplugging the A/C compressor relay from the electrical center on the passenger side firewall to get it started, that never seemed to make a difference. One thing that I did notice however is that when I try to turn it over now the check engine light will not display the "12" code because the two relays for the rad cooling fans keep cutting in/testing/starting, which interrupts the code display cycle.

From reading the various Lumina posts and the wisdom contained therein, it doesn't seem like there is one specific solution for this issue aside from trial and error and replacement parts. I, for one,thought that replacing the injectors would have solved the problem, but now am starting to wonder. I also had thought that it could be sensors, because it would die after it went into closed loop, but after leaving it sit for a couple days in my garage to ensure that it was nice and cold, it started today for about 15 seconds and then stalled out at which time it would not start again. It's worth noting that the car has 290000 kms on it, with a new motor that was replaced at 204210 kms. A close friend has access to all the parts that I could possibly need, but I'm not about to start blindly replacing parts. It's served me well, and if I can get it to stay running I would gladly keep it.

I guess it kind of goes without saying that any and all input is appreciated and the one thing that I cannot readily locate is where to find the Coolant Temp Sensor - many of the posts that I've referenced have pointed to that as a possible failure point.

I look forward to any comments
Regards,
Jeff

[maxwedge]

Was there spark to the plugs when this occurs will it start with starting fluid sprayed into the intake, all basic initial diagnostics for this condition.

[JDMichel]

Right after it died, the mechanic went and got his test spark plug and we had lots of spark. There was also 41-42 psi at the fuel rail and we had lots of pressure during cranking. We didn't try the starting fluid, though.

[maxwedge]

You may not have injector pulse if not it should start with starting fluid.