92 s10 blazer wont run

[BigJohn76]

i have a 92 s10 blazer with the 4.3 Vortech. it will turn over but it will only start once and then not again for the rest of the day. Park is shot on it so when it starts it wants to go into reverse. it did this before and it wasnt a problem. i got the oil changed on it and it started running rough and then shortly after, it died. what is wrong. it has fuel and spark. me and my buddy who went to school for auto tech cant figure it out. PLEASE HELP!

 

[martin]

was it running ok before you changed the oil?, ie. did this problem start immediately after the oil change?

 

[Will]

Is there a safety switch on the shift lever that prevents it from starting in gear? If the linkage is out of adjustment then, you know...

Pull the plugs and compression check it. That's where I would start from.

 

[BigJohn76]

was it running ok before you changed the oil?, ie. did this problem start immediately after the oil change?

yes it did

 

[BigJohn76]

Is there a safety switch on the shift lever that prevents it from starting in gear? If the linkage is out of adjustment then, you know...

Pull the plugs and compression check it. That's where I would start from.

it was fine with the linkage the way it is before. it has good compression and new plugs.

 

[Will]

It was also running before.

One more thing to look at. GM put an oil pressure safety switch on mechanical sending units on some trucks. It's a big round sender. On my diesel it was hooked to the shut down solenoid in the injection pump. Probably connects to the ignition on a gas motor. I don't know how it works but I'm betting it has a relay in it that lets the engine start (juice while cranking), then shuts it down if there is no oil pressure. I'm not certain that the Blazer has it, but I would suspect it does. If this is the problem then your symptoms sound right--spark at start-up, but won't run afterwards.