So first and foremost, hiii!

So i joined this forum to troubleshoot my 91 max. its the 4dsc model.
the car will randomly shut down with no real warning. No bucking, no sputtering, just pfft dead. if i am driving and it does this, i can sometimes save her by either stomping or tapping the gas. regardless of whether i bring her back or not, she WILL shut down eventually.
She seems to just shut down whenever. i can be accelerating, slowing down, shifting into drive, or even sitting still in park. its the damndest thing, but i wont give up on my baby, it was my grandmas car and i bought it from her a month before she passed unexpectedly.

I have done some basic troubleshooting as follows:
I have ran with the MAF unplugged, and plugged in, same thing happens regardless.
I have Removed the IACV and cleaned the thing thouroughly, it was fairly dirty, but no real difference except i was able to get her to idle smoother.
I have replaced the ignition control module, no difference
I have checked the knock sensor, it had came unplugged and been unplugged for a while. repaired connector, reattached, made a difference for a day, then came unplugged again (my fault) and started acting up again. limped home, it would act strange at 2k+ rpms and then straightened out and smooth sailing, til i pulled in the drive and she started acting funny again. at this point, she threw a MAF code and a Knock Sensor code. Properly fixed the knock sensor connector this time, both codes went away, still shuts down randomly as before.
Checked o2 sensor by unplugging, still randomly shuts down with or without.
removed the only ground i could find (passenger side engine bay near headlight) cleaned, reconnected, no difference.
Tested fuel pressure. Starts at 30, when running wiggles at 39-40 mark, when she shuts down drops back to 30 and holds. changed fuel filter as well.
Cleaned MAF with cleaner, no difference.
Have wiggled and jiggled all connections and harnesses, as well as ran with battery dc'ed, no difference.

Someone please give me some guidance on the tests and checks that i should perform. im pretty mechanically inclined, so no ideas will be too extreme! just help me resurrect my baby i hate driving my camaro all over hell and back!

 

does it happen when it's hot and cold (engine temp)?

more when it's cold...or...more when it's hot?
how's your fuel consumption?
is it hard/difficult to start in the morning...cranks a few times before it starts?

 

Well checking fuel pressure and ignition control module are 2 big things that can cause random stalling. Have you checked battery terminal connections or connections at the fuel pump itself? I had a problem with random stalling once and it actually wound up being the fuel pump fuse terminals slightly spread. I pulled the fuse block, squeezed the terminals together tighter so the fuse went back in snug making better contact and never had the problem since. Have you tested the fuel pressure when the stalling occured or squeezed the hose running into the fuel filter right after stalling to see if the pressure was there or not.

 

battery terminal are not really in play when the car is running. when the car is running the alternator pretty much feeds the power to the car.

 

also, the only info ive found on the fuel pressure states it should be 43 standing and 36 running, im getting 30 standing and 40 running. ideas? when she starts it raises very quick to forty, then when it dies it drops back down to 30, also pretty quickly(1.5 seconds maybe)

 

it does it when it hot or cold, but it normally dies about 5 minutes in.
she normally doesnt have a problem starting, but every once in a while she takes a bit longer. tch-tch-tch-tch-vroom yknow? but not consistently


where is this fuel pump fuse of which you speak?
any ideas on how to test the FPR? and how about testing the fuel pump with my DMM?

 

DanNY, The only reason i mention the battery terminal connections is because a buick i used to have once had a problem shutting down while driving due to a bad connection to the positive terminal.

Adam, The fuel pump fuse is located in the fuse panel on the left hand side of the drivers side dash. I cant recall off hand but i believe its in the right hand row but the inside of the fuse panel cover will tell you which 15amp fuse it is. Its just a suggestion im sure its rare that would happen but it just turned out to be a random stalling problem in my case. Not sure about testing the fuel pump with a DMM but perhaps DanNY or someone could chime in to help you with that one.

 

the buick had a dying alternator that's why it would die when you unplug the battery.
you can probably just get a DMM and check voltage and resistance for the fuse.

to the OP...is the car in tune??
new cap and rotor?
plugs ok?

usually you have some bucking or something when it's fuel related. since there's still some fuel in the line..it's kinda like you're running out of gas.

the other thing i can think of is ignition system related. wires, dist rotor, dist cap, plugs. that stuff tend to shut the car right down when those parts are worn. you mentioned that it takes a few crank before it starts up sometimes.

it's probably not O2 related or the MAF related since it "runs" ok normally....and it doesn't matter if it's hot or cold. bad O2...it'll do weird stuff when it's hot....when it's cold it'll still run ok.

with the weird stuff it's best to start with the basics....then move up to more expensive parts. if you don't know the history of the motor do a fresh tune up...(all the items mentioned above and PCV also). always get NGK or Denso plugs. don't by the gimmick plugs.

 

the car purrs like a kitten while shes running, and even upon dying its doesnt sound "bad" persay, just pfft dead like someone killed the switch. as far as a few cranks, yes, 10% of the time it will have to turn over a couple times before starting, but the other 90% its turn the key, it rotates once and vroooom

like you stated, it does act like its running out of gas the way it just dies, but the fuel pressure test tested out that she is holding pressure, not optimal, but holding nonetheless. its specs are 43 standing 36 running, its at 30 standing 39 running, is this acceptable?

i have been considering replacing the distro and distro flag, it appears to have some years on it (its an off pink color, like an old toilet plunger), as well as an oil change and plugs and wires just for kicks, my buddies 350z wont run correctly after using the same oil for a good minute.

where is the PCV located? anyway to test if it's bad?

as far as the buick goes, yeah, thats alternator symptoms all day.

 

PCV is top right on the intake manifold. if you search i'm sure you'll find a pic. it's all steel with one end being threaded.

oh that sounds like an old distributor cap and rotor. get a good set of OEM cap and rotor (it's black in color) and that should help out. i bet your current one was red when it was new and it's so old that it turned pink.

 

If you remove the pvc valve and shake it from front to back you should hear it rattle. If its built up with carbon and sticking the plunger inside doesnt move. For whats its worth i'd just pop in a new one for piece of mind when you do your tune up.They're very inexpensive. The oem caps are hitatchi but if you find the dealership to be too costly i've had good luck and no complaints with BWD. But for the plugs and wires i'd stick with NGK like DanNY previously mentioned.

 

thanks for the advice guys. i have ordered new NGK plugs and wires, as recommended, as well as a Bosch distro cap and a new flag. I have also got a new PCV valve on the way, and plan on doing a early oil and filter change this weekend. i found these parts much cheaper than any parts house on partsgeek so i opted to wait for them to ship versus digging too deep into my limited funds. i will keep you all posted.

 

so while waiting on the replacement plugs and crap to get here, i installed a new air filter, and gave her a nice oil change, and she seems to want to drive much better, no real hiccups after thirty minutes of riding which is extraordinary comparitively considering how frequently she was acting up. i will post an update after i change the ignition coil, distributor, wires and plugs. fingers crossed that baby just needed a tune up

 

I seem to have located the issue, after replacing the plugs, wires, distro, distro flag, and ignition coil as well as a other basic tune ups, she started to run much better, but still intermittently shut off. she finally threw a MAF code once again(note that the code has only shown once prior and will go away and not come back for some reason for a couple days), so at this point i double checked and cleaned my engine grounds, and tested the MAF plug grounds, which tested out fine they are grounding properly. i got her running, and right before she died i unplugged the MAF and she whirred back to life and continued to run. after running for twenty minutes (much longer than she would run since the problem started) i plugged in the MAF again while giving her gas to compensate while the ECM caught up, she died within 30 seconds. started her back up with MAF still connected, died in a few minutes. repeated the same process of unplugging the maf while she was running and she sat there an idled for 30 minutes strong, until i decided to plug in the MAF again and she died again within half a minute. during testing the grounds, i touched the wrong wire and she died in the exact same way she has been dying. this leads me to believe that there is an issue with the circuit in the MAF that is grounding its signal and killing the engine as an act of self-preservation. this would also explain why it isnt throwing a code but every so often because technically the MAF is in working order, its just grounding itself out or something along those lines that create a electrical issue. I have ordered a new MAF sensor and will post results to help anyone else who has this issue.

thank you all very much for your help.