93 PAU Won't Start - What Else Can I Try?

[dagauto]

I'm out of ideas. 1993 PAU (3.8 SC V-6)just passed 200k...I haven't worked on it much but I'm good (or thought I was) with GM's. Suddenly started cutting out. At first, it was possible to restart hard...but now...after all my hard work...it occasionally hard-starts and will run for 3 second to 3 minutes regardless of RPM (still idles at proper RPM and I've had it up to 3,000 RPM.)

All wires, hoses, filters, vacuum lines are good and/or new...same for plugs and wires, fuel filter. Gets plenty of gas but an intermittent spark. Occasionally I will hear a backfire in vicinity of exhaust manifold when trying to start. I checked continuity, voltage and operation for every fuse, breaker, solenoid and sensor I could find...and even brought the tires up to 35 PSI for the first time in its life.

Initial codes showed 18 so I replaced the camshaft AND crankshaft position sensors. Cleared codes...same thing...hard to start, starts occasionally, then dies suddenly.

Then I got a code 22 and replaced the throttle position sensor. Cleared codes...same thing...hard, occasional, or no start. Code 18 reappeared.

The engine runs very smooth (as it did before) when it is running...but just suddenly quits.

One thing I noticed today when it was running for about two minutes and I had it up to 2,000 RPM in Park, is that the car seemed to jump forward a little bit...maybe an inch or so...but in park...it did this twice during that run-up...but only that time. Tranny filter and fluid is new and I never had a transmission issue during the 25K I've owned the thing.

So...I'm out of ideas and maybe someone can help me. I'm really curious to see if anybody can explain why the thing jumped forward a little bit while in Park!

Thanks for ANY ideas...before I go buy stock in Wells Mfg. Co!

[wrightz28]

Originally Posted by dagauto

Thanks for ANY ideas...before I go buy stock in Wells Mfg. Co!

That could be your problem right there. I put a Wells crank sensor on my PA and it ran terrible Raplaced the with one from Napa and all was well (no pun intended)

[dagauto]

You may be correct....everything points to it still being a timing issue. The chain is fine...and the thing DOES start and run OK for up to a minute once in a while.

It's odd that I keep getting a Code 18...most references (Haynes, Chilton, AllData) don't mention a code 18 for this make and model. I found a reference to it on-line...and have read every post in this PAU forum...and the Code 18 never comes up.

One mechanic I talked with said I have "one of those 1992 1/2" engines in my '93 PAU (e.g. it took me 6 tries to get the correct belt tensioner pulley.)

I'll try NAPA and redo the whole thing again...AutoZone has a great websight...but I keep getting suckered into cheap parts...I gotta learn!

Thanks for your input!

[HotZ28]

Three codes are closely linked in the 92-93 3.8L & 3.8L supercharged engines. Code 17 - Spark Reference Circuit, usually referring to the CPS, balancer interrupter ring, or associated wiring problems. Code 18 - Cam/Crank errors, usually related to cam sprocket magnet, timing chain, cam sensor or associated wiring. Code 41 -Cam Sensor Circuit, may be related to the CPS, cam sensor or associated wiring. Keep in mind, if you are only showing a code 18, this does not necessarily mean that the problem is limited to that code.

BTW, the popping noise and lunging forward could be a worn transaxle drive chain. When you rev the engine, the chain will pull out the chain slack and when you let off the throttle quickly, the slack in the chain reappears and will try to jump the sprocket, hence the popping sound and lunge forward scenario.

[Bassasasin]

Have you replaced the Ignition Module?

[dagauto]

Originally Posted by Bassasasin

Have you replaced the Ignition Module?

Thanks...that was the culprit. Still ran a litle rough after I replaced it so I changed out the Wells Camshaft and Crankshaft sensors with higher end NAPA parts. Now the thing runs like a clock...albeit a clock that runs 2 minutes slow every hour. But that's how she was before.

Again, thanks for all of your help. This is the first forum that I've ever gone to on-line where I was able to get useful, knowlegeable, and correct assistance! I'll be back!