1989 Jimmy Stalling

[azsiggy]

So I have a 1989 jimmy that I fell in love with the moment I saw it untill it started being mean to me

I have no problems with it when starting or when it's running cold but when it warms up it often sputters, backfires, my rpms start flying up and down (by 2-3000 sometimes more) my battery gauge drops and it dies, if I wait a little while 10 mins or so it will start again only to repeat the scenario. It doesn't happen all the time (usually only when I have to be somewhere) but it is on a steady enough basis that I don't drive it if I don't have to. I've taken it for a diagnosis test but was told it didn't show anything, someone tryed to charge me for the heat stove on the throttle body but that didn't fix the problem, I've checked all the obvious stuff like plugs, wires, changed a couple of gaskets, the ignition coil...

I am slowly going crazy not to mention I'm starting to really dislike my truck, I know it's old but it only has like 230 000 K on it and before this started happening was running like a dream, any thoughts what so ever would be greatly appreciated

[bobcat5544]

The top things to check with an engine that has over 230,000 mile.

Check to see if the Timing chain is streached.

Check the distributor module

Coolant Temp Sensor

Bad or Corroded ground wire

 

Let me know if you need to know how to check for a streached timing chain or a bad distributor module

[minibike132]

I don't think a timing chain is likely the cause

I have no problems with it when starting or when it's running cold but when it warms up

a timinig chain shouldn't be heat or run time sensitive. I'd check back pressure (possible catalytic converter issue) and at the time of failure take off air cleaner and make sure the injectors are both providing a good flow.

[minibike132]

This isn't to disagree with Jonesy, at 230k you should be checking the timing chain slack just because it's old.

[bobcat5544]

The reason I say the timing chain is when the chain is streached it retards the cam. When the engine it cold the pcm retards the the timing until warm. Then it will advance once warm. With the cam retarded and timing retared the truck will run close to normal, but when the timing starts to advance as it warms up it will start to run ruff and backfire because it is firing before the intake valves close.