Crank/no start

[blk\blk90]

My new to me 91 has been having some issues lately. After sitting a few weeks I couldn't jump it, so I pulled the battery and charged it with another vehicle. Put it in and started right up. I pulled onto the road and at about 50% throttle it just falls flat on its face. It did that twice, and has done it randomly since I bought it. After coming around a turn and downshifting to second, it did it again. Cluthed in and tried first, died. Wouldn't start and killed the battery. Pulled it home and got a new battery in and now it just cranks. The tach does move while cranking.
I also found out my neutral safety switch has been bypassed, as the car will crank w/o the clutch in.

I tried pulling codes only to find my mil light doesn't work so I tried reading voltage at the eec port. I'm just getting constant 12v there. So I bought a code reader and it's not reading anything either. Went to try and pull the ecu and it felt really wiggly. I tried undoing the 10mm bolt on the engine side but could never get it to pull loose. Also, the nut holding the plate on the engine side was loose. Tightened that only for it to snap the stud. Awesome.

I have no clue if I'm even heading in the right direction since I cant pull codes. Before the car would idle just fine and the falling on its face was random at best. It has an lpm(?) And I have a spare dis, x2j, and CPS sitting around if need be. Any help is much appreciated.

 

[sperold]

Shoot some "quick start" in the intake hose while it is cranking to see if it momentarily runs.

There is a fuse that feeds the coils among other things, have a look at that. I think it is 10 amp.

See if there is spark at the plug with a spare spark plug on a metal part of the engine.

Could be the crank sensor, but don't jump to that conclusion just yet.

The tach moving is good news for the cam sensor, but it is not a vindication. Try the short burst starting attempt if you have not done it so far; I think you can unplug it as well if the crank sensor still operates well.

 

[luigisho]

keep the lpm out. reset the pcm with pulling the power. do you think the pcm wiring harness is in there tight and making good contact across all the wiring/pins?

 

[Irish Pride]

Without being able to pull codes you are shooting in the dark. I did have a similar situation years ago when my 89 had a LPM. I lowered the glove box and drove around with it hanging. Whenever it would start to sputter I would reach up and tap on the PCM and it would clear up and start running good. Once I determined it was either the PCM or the LPM I removed the LPM to eliminate it from the equation. It still had the same problem and would still correct itself when I tapped on the PCM. At that point I replaced the PCM and it ran perfect ever since.

 

[rubydist]

based on your description, I also think the pcm is a very likely candidate, and I would replace that next.

there is a nut molded into the connector housing and it sounds like in your case that nut is just spinning inside the connector housing, not letting the bolt get loose. iirc, when I had that happen I had to pull the entire pcm through the firewall with the wiring harness connected and then open the pcm cover to get to the connector housing to grab that nut with a pliers or vicegrip.

 

[blk\blk90]

Had to wait till dark to check, but I do have spark. I dont have anyone to help me with starting fluid, that may have to wait till tomorrow night. Is what I described symptoms of a dead fuel pump?

 

[rubydist]

after cranking for a while, pull a spark plug. If it is wet, then you have fuel. If it is dry in that situation, it is very likely you have no fuel. There are several possibilities for no fuel, including bad pump, bad ccrm, bad injectors, bad pcm, etc.

 

[luigisho]

Do you hear the fuel pump prime when you turn the key to run just before engaging the starter? These pumps are loud and easy to hear when they prime

 

[sperold]

If there is atomized starter fluid anywhere in the induction system, it will start and run a few seconds (if lack of fuel is the problem). You don't need a friend for this procedure.

If you have too much fuel, then the procedure is to hold the gas pedal to the floor while rolling over the engine.

Hope this helps.

 

[blk\blk90]

Ok, car started with starting fluid, and I can hear the fuel pump. I have pressure at the rail. I pushed the Schrader valve and fuel spurted out. Cranked it and pushed it again and it shot out again. I'm almost wondering if it could be the fuel filter? But could that completely stop the motor? Either that or the pcm is stopping the injectors from firing? I completely forgot to pull a plug and check.

 

[rubydist]

now you are narrowing things down. if you pull a plug and its dry, then the injectors either are gummed up and not spraying fuel, or the pcm is not commanding them to fire. if you pull a plug and its wet, then you most likely have a timing problem.

 

[luigisho]

and if your pcm has been flopping around it could be an issue. an old fuel filter probably not going to stop it up but they are cheap and a good idea to get a fresh one in there every now and then.

check the plugs as suggested above and I would consider removing the pcm, freeing the wiring plug bolt and trying your extra x2j.

 

[Irish Pride]

Then when you get the PCM off, there's this.

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/161195716572

 

[blk\blk90]

Thanks Chad! I went ahead and bought it since I'm betting pcm and I cant seem to get mine out. I'm gonna go ahead and listen to the injectors just in case, but the not showing codes thing is probably a giveaway. I wanna thank everyone for the help; this has definitely been a head scratcher. I'll report back after work tonight if this cold front moving in doesn't stop me (car is outside).

 

[luigisho]

rubydist in #5 above posted how he got his out and apart. removing it through the firewall

 

[blk\blk90]

Yeah, its 25 and snowing in the trailerhood. Dont think I'm doing anything tonight.

 

[luigisho]

Wow. This early in Texas?

 

[blk\blk90]

Wow. This early in Texas?

No kidding. But I'm up in the panhandle so weather here is erratic at best. Its gonna be 75 on Saturday.

 

[blk\blk90]

Finally got a helper out so I could listen to the injectors. As I had the stethoscope on one my gf cranked it. And the car started. And just sat there idling. It had a hiccup and completely died for a second and came right back up. Idled for about 5 minutes so I decided to drive it around the block. Closing the hood made it stumble. Twice. So I got in and got on it to about 4k and let off and it died. Wouldnt restart. Then it decided it wanted to restart. So I reversed it back down the block and did another heavy acceleration test and it died again. I dunno, I'm at a loss. This car is haunted or something.

 

[blk\blk90]

Finally got the pcm out. Had to have a 2nd person turn the bolt while I pulled on it. With the new computer it seems to be ok, but I didnt take it out for a test, just up and down the trailerhood. It still stumbles when I shut the hood and there was a loud clunk from the right rear when I pulled away. It smells like burning plastic and the motor doesnt sound right. It sounds burbly when accelerating and ticks. Oil light comes on when idling and my pressure guage still drops to 1 or 2 psi once warmed up. Oil dipstick says it's fine. I'm gonna take it out today and see how it does.