'96 Metro starts then immediately dies

[riverat440]

Off hand has anyone had a problem with losing spark immediately after getting started? It will fire up but within a couple of seconds it dies. I suppose I could go get a used distributer and do a swap but I would like to be able to pin point the problem before I start buying parts. Someone told me to check the crank sensor but Mitchells only shows a cam sensor in the distributer.

[Johnny Mullet]

Has there been any recent work done to the car? If an oil pan gasket was used, the gasket is too thick causing the crank sensor signal to be erratic. Use RTV only.

[Woodie83]

There is a crank sensor between the oil pan on the passenger side end of the engine and the accessory drive pulley. Get a Factory Service Manual. Seems to me I vaguely remember something about the fuel pump not running if the alternator wasn't turning. There's a feedback circuit in the alternator that reports back to the PCM, maybe that's bad or disconnected.

[91Caprice9c1]

Any codes?

[riverat440]

Originally Posted by Woodie83

There is a crank sensor between the oil pan on the passenger side end of the engine and the accessory drive pulley. Get a Factory Service Manual. Seems to me I vaguely remember something about the fuel pump not running if the alternator wasn't turning. There's a feedback circuit in the alternator that reports back to the PCM, maybe that's bad or disconnected.

I think you may be a bit confused. The crankshaft position sensor would read crankshaft position off of the crank pulley. If it were reading off of the accessory pulley what would happen if the drive belt slipped? The feedback circut would come from the distributer not the alternator as the distributer is driven off of the camshaft hence the camshaft position sensor, and yes if there is no signal indicating the engine is running some models will shut down the fuel pump. Seems I remember working on one of these a few years back that was eating alternators and each time it came in the alternator was fried but it did run. Customer kept putting on used alternators and paying for the labor until the 4th try he finally got a rebuilt.

[riverat440]

Originally Posted by 91Caprice9c1

Any codes?

No MIL. I just acquired this thing to do a hydrogen generator with it so I am in the early stages. It has been sitting, because of the no run situation, and doesn't even have a permanent battery yet so it hasn't had a chance to find its own problems. Even if I did install a battery it won't run long enough to set a code.

[riverat440]

Originally Posted by Johnny Mullet

Has there been any recent work done to the car? If an oil pan gasket was used, the gasket is too thick causing the crank sensor signal to be erratic. Use RTV only.

I haven't looked yet but with what you are saying the crank sensor must be mounted to the oil pan. Thats queer. I'm not even sure the crank sensor has anything to do with spark as usually in a system with both cam and crank sensor the cam sensor controls spark and crank sensor controls fuel. Thanks for the info though, I will try to get it on the lift today and see what is up with the sensor and the oil pan.

[Woodie83]

Originally Posted by riverat440

I think you may be a bit confused. The crankshaft position sensor would read crankshaft position off of the crank pulley. If it were reading off of the accessory pulley what would happen if the drive belt slipped? The feedback circut would come from the distributer not the alternator as the distributer is driven off of the camshaft hence the camshaft position sensor, and yes if there is no signal indicating the engine is running some models will shut down the fuel pump. Seems I remember working on one of these a few years back that was eating alternators and each time it came in the alternator was fried but it did run. Customer kept putting on used alternators and paying for the labor until the 4th try he finally got a rebuilt.

No confusion at all on my part, the crankshaft position sensor is mounted between the engine block and the accessory drive pulley. Nothing in that sentence hints as to what it reads, I'm merely telling him where to look.

The alternator absolutely has a feedback circuit and I think I remember that on some years it is used to disable the fuel pump if the engine stops running. Many things changed concerning the engine controls on these cars over the years, the fact that you "saw one once" that did thus and so is anecdotal.

[91Caprice9c1]

If you weren't getting a signal from the distributor you wouldn't get spark to begin with. Which brings me to my next question: How did you confirm the no-spark? What have you done already in terms of diagnostics?

Also, you're wrong about codes not setting immediately. There are continuous and non-continuous monitors. Vital inputs like crank sensor short/open, cam sensor short/open, and misfire counts are all continuously monitored. What separates misfire counts from the other two I mentioned is that they have a threshold to surpass before coding, but they are still counted, and you can spot them by looking at mode 6 data with a generic scan tool.

-Matt

[riverat440]

Geez I guess I learned my lesson coming here for some friendly advice. Just thought I could save some time by having someone with similar experiences relate. Instead I find morons and know-it-alls neither having anything constructive to add only wish to belittle others for their own self satisfaction. I'll find the time to diagnose it myself as I always have in the past.

[91Caprice9c1]

Originally Posted by riverat440

Geez I guess I learned my lesson coming here for some friendly advice. Just thought I could save some time by having someone with similar experiences relate. Instead I find morons and know-it-alls neither having anything constructive to add only wish to belittle others for their own self satisfaction. I'll find the time to diagnose it myself as I always have in the past.

Please, share your wisdom with the community when you figure it out. That we may learn from you.

-Matt

[Woodie83]

Don't know why you came here and asked if you were just going to dispute all the facts you were told.

[91Caprice9c1]

hey woodie, nice flying spaghetti monster!

[Woodie83]

I stole it from somebody over at TeamSwift, thanks.

[Idaho_Mechanic1984]

Does it do the same thing if you push on the gas pedal to keep it running?

If it stays running that way - I would look into the idle control system.

If that does not change anything then I would look more at sensor possibilities and/or coil/ignition possibilities.

Please let us know how it goes!

-Dale in Idaho