How do you change oil pump in 89 gmc 4.3 v6 s15 jimmy
I'm going to simply "spitball" an answer because i don't know WHY you think you need to change the oil pump.
1st, IF the oil pressure gauge isn't showing any pressure, or low pressure, AND there is no engine noises such as knocking or loud tapping, I would suspect a faulty oil pressure sending unit. IF there's a deep knocking sound then an oil pump isn't going to solve the problem. That is UNLESS it turns out to be what I ran across on a 1991 S10 4x4 with a 4.3. There was a "knocking" sound which I traced to the cover plate of the flywheel/flexplate. Turned out to have a cracked flexplate. Changed it and all was good.
I have a 1985 GMC that showed low oil pressure, yet there was no noises coming from the engine to confirm low oil pressure. I changed the pressure sending unit and it fixed the problem of "low oil pressure".
Now IF you're dead set on changing the oil pump, get ready because it isn't a 10 minute job.
You'll more than likely have to at LEAST raise the engine somewhat as (I'm guessing it's 4x4) the oil pan has a deep sump area for the oil pick up. This is so the oil pan can be shallow in the front area to clear the front differential and cross frame area.
Then you get to try to wiggle, twist, wiggle some more, the oil pan out from between the bottom of the engine/crankshaft, and the cross member of the frame AFTER removing all of the bolts that hold the oil pan in place.
IF it were me, I'd be almost inclined to simply pull the engine, at least part way out of the truck, to gain better access to the pan. AND you wouldn't be fighting trying to keep the oil pan gasket in place while doing the wiggle/twist putting the pan back into place.
Hope this helps.
1989 GMC S-15...
on Feb 20, 2015