'90 3.1 Lumina stalling when warm

[Wilbur]

Hi everybody, I would appreciate any help you can give me, my car has been down for 2 weeks, and my truck is killing me in gas.My problem is my 3.1 shuts down after 20 mins. or so with no fuel at the rail, no codes, just series of 12s (safe) I have replaced the fuel pump/filter (napa) ECM,CPS still same thing, runs and drives fine untill warm, then Blahhh wont start untill completely cool, thought it could could be the FPR, but whats to heat up? I swapped out the relay and still S.O.S. I need help. Wilbur

[Wilbur]

Has nobody else had this problem? I've been reading 60* for a few months and dont remember seeing any post like this, darn gremlins!!!

[bszopi]

I'd look into the coolant temp sensor.

Similar problem (although on a DOHC) : http://60degreev6.com/showthread.php...nt+temp+sensor


Values to check for proper operation : http://60degreev6.com/showthread.php?t=25015

[Wilbur]

Thanks bszopi, Ill check into that tonight and thanks for the thread... Wilbur

[GutlessSupreme]

If not the coolant temp sensor, ICM and/or Coils next... my Cutlass did it a few months ago and I couldn't figure it out. I believe the shop replaced just the coilpacks, though I'm not positive.

[Wilbur]

Thanks gutless & bszopi, I tried new coolant temp sensor and coilpacks and still the same thing, gets warm,shuts down, and no fuel. Man I'm baffled,I miss my car. Anymore ideas? Thanks Wilbur...

[Juglenaut]

When cold, unplug the throttle position sensor, try and start it, if it starts let it idle don't push the pedal if it doesn't start plug the TPS back in a start it then unplug the TPS and let it idle.
If the engine stalls when you unplug the TPS something is wrong with the fuel advancing regulator perhapse, if it doesn't start with an unplugged TPS something is wrong with the map.


Something is failing when it is hot or warmer than 120 degree F, start ruling thing out by casuing fault codes:
Pull the map plug while running, does it stall?? if not rev it some and let it fault.
Pull the IAC and TPS plug while running, does it stall?
Pull the coolant level and corrosivity sensor plug.


These sensors on 1988 to 1990 3.1L Vin T engines are circuited together and share a common ground:
Map, Coolant level, TPS, EGR Electronic only.

Parallel sensors relative:
Intake air temp sensor, engine coolant sensor, EGR Electronic (not digital)

Integrated association interpolated and active:
Knock sensor, Air select switch can cause EGR faults digital and electronic, and can cause the tps to shift suddenly. Electronic EGR's are ground referenced by the TPS.

[Wilbur]

Thanks juglenaut, I unplugged ts, no change,coolent level sensor the same, no change,IAC again no change, I tried the map it still ran but I forgot to rev it up to get a code, and now like you said atabout 120 it doesn't want to run, whatever it is, I think you are on the right track, thanks for any help you can give. Wilbur

[Wilbur]

OK Now I let it cool off for a while, unplugged the MAP, revved it up , the onlycode that came up was 13, open O2 circuit, would that be because the MAP was unplugged, or is the circuit open? or bad O2?Thanks back soon..Wilbur

[Wilbur]

Still no luck, Its turning into a money pit!!

[Wilbur]

wanna buy a Lumina

[3100 MPFI]

It just sounds like a bad MAP sensor to me. I had this happen to me once, and to two different frends TWICE. In both cases, replacing the MAP sensor fixed it in all cases.

I know that there is still a lot to do that can diagnose it, but it sounds like a problems that happens in CLOSED LOOP, and that is one of the only things that has happened to me like what you are experianceing.

[Wilbur]

Thanks Taylor, I tried swapping out MAPs with a friends '91 Lumina, but I didn't remove the fuse for the ECM, I will try that again as soon as I have access to it.I think you are right about the close loop thing though, This is driveing me crazy

[Wilbur]

Well tried new MAP sensor and no luck, but now it is giving a code 34,(low voltage,high vacuum to MAP) aaarrrrggghhh, It didn't do that before?!! I know the sensors are in series, but I'v checked them w/ tester,the only one in question is the coolent level sensor,be another 2 weeks before I can afford that. I am befuddled....

[torq455]

you said you repalced the coil packs. did you replace the ignition control module? usually that's a prob after things get fully heat soaked. shut it off and won't restart until cold. got my extra one from ebay. check for vac leaks too.