93 sub engine died on me

[fliescher]

Yesterday evening I tríed to go shopping and my 93 sub LT 4x4 started just fine. After about 1mile the engine jsut died on me. No restart possible, although it´s cranking fine. This morning I tried to recover it and ... it started again. But also only for about a mile. Fuel filter is fine, circuit breakers checked and all the good stuff. Anybody any ideas?
Thanks
Uwe

[maxwedge]

You will have to check fuel pressure and spark to start off with, when it dies of course.

[kalafre]

Just a shot in the dark, but you might want to try replacing the Fuel Pump Relay - it's under the plastic cover on the passenger-side of the firewall.

[fliescher]

I checked the sparks... fine. Fuel pressure ~ 11. Thius morning it started again and ran for about 15 sec. Could it be some ECS sensor?
Uwe

[maxwedge]

It ran for 15 sec, then what spark gone? fuel pressure /injector pulse gone?? Need more info you are on site we are here!

[fliescher]

Spark is still working as well as fuel pressure still fine. But I must admit, that I don´t know how to check the injector pulse. But there is no fuel injection in the carburator while cranking

Originally Posted by maxwedge

It ran for 15 sec, then what spark gone? fuel pressure /injector pulse gone?? Need more info you are on site we are here!

[fliescher]

There were a couple of reasons and the chain of event is not known for sure. A wire in the theft deterent system was broken as well as the ignition module. Furthermore did the fuel pump relay got whacked together with the fuelpump

[GM Cajun]

I had an '88 Sub and the same thing happened to me. If you're getting spark then take off the air breather and watch the two fuel injectors in the throttle body while someone tries to crank it. You should be able to see the fuel squirting out. Also listen for the fuel pump to kick-on. If you don't hear the pump check the relay and the pump like they said. If you can hear the pump but see no fuel coming out the injectors it may be the Ignition Control Modual. On my '88 it was located under the Distributer Cap. I replaced it and my Distributer Rotor and that fixed the problem. Also, you may want to disconnect the negitive battery cable for a few minutes and see if that has any affect (I'm being serious). I had to do that after I replaced those parts.

[Shayne7s]

Its your Engine Ignition Module. I have a 93 Suburban and this has happened 2 seperate times to me over the years. Each time I went through all the above troubleshooting. One way to check is to carry a Timing light with you. When it dies, see if the timing light fires. If not it is the module. Trust me I spent weeks chasing this down

[kuehjo]

Not to reopen an old link, but let me get this straight -

If the ignition module dies, you can STILL get spark, and yet have a bad ignition module preventing the vehicle from starting?

Hmmmmmm....... That's got me thinking, if that's true....

[kuehjo]

Ok - did some reading. Don't have the Suburban manual so I had to turn to my 1988 IROC Helms manual, but here's what I found.

Diagnostic chart A-3 (5.0 liter TBI)

if spark, then check for spray from injectors.
if no spray, then probe injector terminals
if no light, then disconnect distributor 4-wy connector and probe
if injector light blinks, then faulty ignition control module.

SOOOO!!!!

It turns out that the above posts are exactly right - you CAN get normal spark and have a faulty ignition control module. Makes sense too - these things fail when they get hot. Which is exactly what happened as you started to drive.

Replace the module, apply silicone grease (DON'T FORGET!!! THIS IS WHAT KEEPS THEM COOL!!!) and you're good to go.

Learn something new every day...