3.1L cranks, won't start when warm

[Jeffi]

94 APV won't start if left to sit after driving. No spark and no gas at injectors. little while later (5 min to 2 hours) will start right up. Can hear the fuel pump. Any ideas short of swapping out ECM?

[xjoeharperx]

From my experience id swap out that ecm...have had so many 92-95 luminas with bad ecm's its not even funny anymore...all have that same problem with stalling and not restarting..

[dxrflyboy]

Try tapping the ECM with a screwdriver handle when this happens. I had that happen with an '89 Cavalier. Tapping the ECM made it work when it quit. Also check all power and ground leads for intermittent open circuits. There are multiple power and ground leads. You will need to check them all.

Dan

[MonicaNY]

Where is located ECM in Chevy Lumina APV 1994 monivan? Is worthed to replace it? How much is it? Thank you.

Originally Posted by dxrflyboy

Try tapping the ECM with a screwdriver handle when this happens. I had that happen with an '89 Cavalier. Tapping the ECM made it work when it quit. Also check all power and ground leads for intermittent open circuits. There are multiple power and ground leads. You will need to check them all.

Dan

[xjoeharperx]

The computer is behind the glove box.

here is link for computer http://www1.autozone.com/servlet/UiB...7C%7EEA%7C%7EV

here is another http://www.partsamerica.com/PartDeta...pe=248&PTSet=A

[Jeremy-WI]

Is the CKP connected to the ICM on these? Could a messed up ICM keep the ECM from getting the reference pulse to energize injectors, fuel pump, and send the timing signal to coils
Guess fuel pump could get energized through oil pressure sender if its like full size trucks

[xjoeharperx]

To the best of my knowlegde the crankshaft position sensor on this year would not keep the car from running..it would send a code if it did malfunction..the cam position sensor would keep the car from running..Now that you reminded me the 3.8l v6's would suffer the same problem..after running the cam sensor would get warm and lose its magnetic suseptibility and fail to trigger the ignition, causing stalling and no hot start condition..But I believe the root cause of that was engine overheating...good post Jeremy

[MonicaNY]

Thank you. Do you have any idea which sensor can be broken (ignition one , other, where is located?)?
Is there any way to disconnect any crazy sensor/another stuff to make my car running?
I am feeling I am NOT an owner of my OWN car anymore because now ECM OWNS MY CAR without paying for it !!!


[quote=xjoeharperx]The computer is behind the glove box.

[xjoeharperx]

The best way is to go to a shop that has a diagnosis computer that can read a data stream..
This enables the mechanic to read a multitude of sensors at once...usually unplugging sensors wont make a car go..

The ecm might seem like the just have to lay the smack down on it

[MonicaNY]

Thank youvery much . ECM is just an effect of someone's idea...how they call this guy with 50 billion dollars.... ? Heloooooo Bill you have to fix my car!
.......Meantime I have a next question. Someone told me there is an iginition sensor under an engine (such a great location for a sensor !... ) which (or connection, wires) get wet or oil very often and then ECM reads it crazy. Is it a true? Is it worthed to go under a car and check/replace it?



The ecm might seem like the just have to lay the smack down on it [/quote]

[xjoeharperx]

You can have it checked out, its not a bad idea, It will probably cost you $90, thats 2 labor hours of diagnostic time. Thats about the standard for these kind of problems..The unfortunate thing is that they might not find anything.....The first time i came across this problem i had the car for 5 days, I couldnt find anything wrong with it. It would run fine for a while and then all of a sudden stall for no reason. It was a pain in the ass to restart and then not show any problem for a while...The usual sign that the ecm is bad is when it refuses to start the ecm shows that it is reading 26 volts. This is determined by reading the data stream with a gensys diagnostic tool... Of course i have run into this problem so frequently since then we have a spare computer on the shelf and its the first thing that i swap out, 90% of the thats it..
Have the shop test out the cam position sensor, the crank position sensor, the coolant temp sensor and the air temp sensor. Dont let them replace any of these unless they can positivly show you that they are malfunctioninig.

[MonicaNY]

Thank you very much ...you know ....I am missing old good times when everything was a simple and only REAL GHOSTS were present ....

[Jeffi]

Well, I had the ignition module checked out on a tester 20 times or so. It got plenty hot but never failed. Tapped the ECM and the van started for a second or two. Replaced the ECM with one from the wreckers. Same service number. Started and ran and I turned it off after 1/2 hour. 15 minutes later, no start. Lots of crank, bt no gas at the injectors and no spark at the coil wire. I really don't want to have to start tracing wires, especially on speculation. Here's another thing, according to both my manual and the chev parts guy, there is no camshaft sensor and no crankshaft sensor on the 94 Lumina van with the 3.1. What gives? Different sensors for different lumina 3.1s? This one is a "D" series.???!!?!?

[dxrflyboy]

You're at a point where you will need wiring diagrams and a factory shop manual (or another reliable source of diagnostic flowcharts). The wiring diagrams will show you which ECM wires are power and grounds so you can verify that they are intact when the engine quits. Your van probably has throttle body injection and a distributor, so the ignition module provides the crank/cam signal to the ECM, unlike 3.1 engines in cars of that vintage, which have port injection, no distributor, and a crank sensor. If all the power and ground leads are intact, check to make sure the ignition signal is getting to the ECM (a wiring diagram will indicate the correct wire). You will need a labscope to verify this.

[Jeffi]

Thanks for the reply, Dxrflyboy! I think you're right. Here's an update. Induced a no start and checked the IM in the van. 11+v at + and C terminals. put 12V to P terminal and showed a slight drop at C. Took the 12V away and got a spark at the coil wire. Put it back together and still wouldn't start. So now I'm thinking pickup coil but now I can't get it to fail. Maybe a fault in a wire I wiggled??? I want a carbuerator, points, mechanical fuel pump and a choke! Can anyone point me toward a pinout for the ECM??