shazam74

Hey guys,

I've been blessed with an inherited 84 Z51 with 75K on her. I've been going through the typical stuff, weatherstripping, replaced the rack and high pressure line recently (OMG what a difference in driving now), new Rad and hoses, some vacuum lines, wires and plugs, starter, the usual stuff with a car of this age topped with a father that drove it 2K miles in the 20 years he owned it. These cars love to be driven and in Fl, that won't be an issue from now on.

Anyways, today I took her to work since I just had the rack redone to show it off and put some miles on it. I hit a final speed bump and tapped the gas, the engine went dead. Full dash lights stayed on, no sputter, just engine died. I put her in to park and she fired right back up. I've take it over train tracks and some bumps without issue over the couple months I've had it but this is the second time it has done this in the lot at work. The lot has 4 of them and it happens after the 3rd bump.

Any suggestions on where to start and what to look at? I have baby #3 coming in a couple days so I may not be on to update the thread as much but appreciate any and all replies.

Whaleman

Wouldn't it almost have to be a loose wire connection? Dan

1984Z51auto

Check the internal wiring inside the distributor and the distributor connector to the main wiring harness at the rear of the engine (near the oil pressure sender behind the intake manifold). The heat from the engine is hard on the insulation, plastic and rubber parts. It could also be the distributor itself failing, try tapping it while the engine is running in park to see if it quits.

shazam74

Thanks guys, will do when I have a moment. Cap and rotor were on my list soon so I can dive in a little deeper and check the rest of the connections while I'm tooling around.

383vett

Sounds electrical. Just wondering, what was your fuel level?

shazam74

I had a half tank when I made it in to work this morning.

81c3

Possibly the electrical connection feeding the pump & float at the top of the tank that may be loose, or on the verge of being broken in two....

DUB

My vote is for something electrical due to how the engine dies so quickly and does not sputter.

This sounds like a good candidate for some test equipment to be attached to it because if it is failing on the third speed bump on a constant basis....then watch a fuel pressure gauge and setting up other test fixtures can be done to try to find why it does....BUT...it will crank back up right away.

I do know that bad IAC's can cause an engine to die when coming to a panic stop..and the engine will crank right back up.

DUB

1984Z51auto

Hey OP: Are you out there or did the '84 hit a bump, quit and the gators got ya?

Seriously, any progress on the stalling?

shazam74

Yep, gator took a bite after it stalled. So I have a new addition to the fam and haven't been able to play around a lot with the toy. I have taken it to work and likewise gone over bumps without issue as long as the you maintain a stead light foot to the pedal. I'm really thinking it's fuel supply related and not truely electrical (cutting the pump off that is some it continues to run after hitting rail road tracks and additinal). I would assume that the car would quit on me if hitting those rail road tracks since those are pretty crazy. All speculation till I get some time to dig in to it of course and check the suggestions. Thank you guys.

On a side note, my outer rear tail light turn element burned out. With the damn ground effects on it, it makes it impossible to go under the car without some disassembly. Looks like in popping the lights out to get to it and slicing the crap out of my arms while going through the plate cover before I can get her back on the road. Lots of fun to be had.

1984Z51auto

Yes, you want to use long life bulbs when you do the tail lights... changing them on the early C4s is a pain. The later models have two screws. Chevy made constant progress on the C4s!

shazam74

Huge pain. This is the second time doing this and I had used long life the first round. Ugh, the joys of an early c4. It still puts a smile on my face when I fire her up and get her a little sideways once in a while like my dad use to.

DUB

I do not know if I would consider it a huge pain. Many other things I know that would be a part of service are just that...A HUGE PAIN. Servicing the bulbs is a bit more involved than the older taillights that had screws to hold the light housing in. But changing a light bulb in the rear is really not that bad.

If all is still factory..all you need is whatever screwdriver to remove the license plate...then a 7mm for the reverse light and then a 10mm to remove the inner taillight housing.
(OPTIONAL) There is a 10mm nut behind the reverse light that if it is removed will allow the bumper cover to flex a bit more....assuming it is urethane.

If I want to get my arm chewed up..I can go up from the bottom and get to it.

AS for back to your issue of it cutting out. IF it dies and no sputtering like you wrote...I am still convinced you have an electrical issue. SO driving it with a fuel pressure gauge hooked up and watching it and getting it to die and seeing if you have fuel pressure that is maintaining...then that obviously will let you know it is not fuel related. If you loose fuel pressure..it still can be electrical due to the fuel pump is electric.

It is obviously now down to you having the time and performing diagnostics on it as I know you are quite aware of.

DO NOT be surprised if the wiring harness strap that is more than likely on the back of the block where the transmission is bolted has cut into your main wiring harness. I HAVE seen this first hand...and that is because GM used a metal clamp...and when wires cut into it...it grounds them. There was service bulletin on this issue and GM changed that strap to a plastic one.

DUB

shazam74

I know new guys like me have a tendency to not update after things have settled on there issue. I ran through connections to the pump and all looked good so I started looking at the ignition. I made me way to the distributor and HEI pigtail to the battery and found there to be a series Bubba job on that. The wire was spliced once as an extension and again for a newish end. Both jobs were horrible and covered in poor conditional electrical tape. I pulled out the splice and put in a new, proper gauge pigtail/connector properly soldered in place with shrink tube, and I haven't had the issue since. Been to work and over those bumps about 20 times since with zero issues and it appears to run a bit smoother.

Hot Rod Roy

Two babies doin' good!! Congratulations!!

383vett

Nice!

vette196

CONGRATS (on the new baby)....it doesn't take long at all for them to grow up, see my avatar.....

Gibbles

For the tail lights, i found it easiest to pull the fuel pump...
kust make sure you replace the hose ends and don't reuse them.
tons of room once that pump is out of the way!

If your arms are skinny, most pull the license plate off, but it's still a pita.