Daily driver 86GT conv run problems

[erratic50]

Had an issue late last night where my son's 86 started running horribly rough then it cut out, stumbled, sputtered and stalled. It fired again but would barely idle. Then as quickly as it did this it started running fine again.

The car has around 120K miles and as far a I know original ignition except plugs, wires, and cap.

Its running a VM1 ECU out of my 86. Grounds are all home run back to the battery. Fuel pump is new last spring as is rubber pump line and gas gauge pickup.

When it sputtered the tach also went well past 7K even though the motor was barely running.

Im about to scan it for codes. Based upon my past experience with my 86GT I suspect I'm going to see ignition pickup or ignition module.

Looking for a few other ideas so hopefully this repair doesn't take forever.

Im tempted to toss in a reman dizzy or get a new pickup and rebuild it myself then add a new ignition module and go from there.

Id use my 86 for parts to test with but it's running great and I don't feel like messing with that tortured old bullet under the hood of mine right now.

[erratic50]

Codes show zero. The only thing I found was oily residue on the rotor.

Bought a new autozone dizzy complete including cap and rotor, steel gear. Cheaper than pickup, module, cap, rotor separately. Come pre-tested for what it's worth.

[boboli]

Codes show zero. The only thing I found was oily residue on the rotor.

Bought a new autozone dizzy complete including cap and rotor, steel gear. Cheaper than pickup, module, cap, rotor separately. Come pre-tested for what it's worth.

Save your old distributor. I put 1 of those new distributors in my 89, years ago. The pickups in them are junk. I ended up having to warranty it 2 times. So just because they're new and tested, doesn't mean they are any good long term

[erratic50]

The module on the original dizzy was a wells. The pickup looked factory. It had the stock distributor part number on it. Much to my surprise it had more slop between the shaft and the bushings in the housing than anyone would expect. I wasn't really OK with it so a new fully loaded dizzy was the route we went.

The plastic that transitions from the metal base to the cap and locks the cap down is a total piece of crap. The cap could move around a degree each way relative to the base. I could actually make the motor run differently by wiggling on the cap. Also the latches would fall off every time they were unlatched. I could just see pulling the dizzy sometime and having one fall off in the hole for the shaft and end up in the pan.

No way. Not putting that crap on a car! I put the factory piece on the metal base instead.

The rotor and cap it came with were both a nice piece. Module and pickup seemed ok quality. There was at least effort to get the module metal on the dizzy metal for cooling purposes like it should be.

When I dropped the dizzy in, buttoned it up, hit the key it fired right up like it had just been running. That's what it's supposed to do. No fuss, etc.

I always get the motor to TDC before yanking the dizzy. If it's TDC on the power cycle on an HO motor the rotor will point at a 90 degree to the firewall (#1) . TDC on on exhaust cycle the rotor points directly forward (#6). Just pay attention and no need to fight it around a 2nd time. On the EFI cars if you can make the rotor at a 90 degree to the firewall with the module in the middle of its sweeping motion with the rotor pointing where the old one was when you took it out you're usually golden for getting it up and running so you can time it again.

I dialed it in by ear with the advance plug in initially then revved it and could immediately tell it wasn't quite right. A quick drive confirmed it was almost exactly at stock timing-- unacceptable. After pulling the advance stub and playing with base advance a little more it was right where the motor wants to be.

Funny how you can hear it in the pipe once it's timed the way the motor wants to be. Once it's "there" its just before has just the lightest hint of sounding pissed off or pinging when you rev it.

Happy it went ok. it's like hearing an old friend again.

So far so good on repair. Runs like it's supposed to again. Totally knocks the tires off in 2nd in the rain, etc.

Time will tell if my educated guess about what the problem was is correct.

Still open to other ideas about what else it could be, just in case something comes up at 2 am again.



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[erratic50]

Gave us plenty of extra drama along the way with the heat problems we were battling this summer. Ended up tossing the autozone ignition module and installed a Motorcraft along the way due to it doing the same crap as above again. So far so good now that it runs cool again.