Help! Oil pressure sender just broke off!

[someotherguy]

Yes, they do have the brass elbow.

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It's no big deal to install another elbow and then install the sender into it. Done it...after breaking one off many years ago attempting to change the sender, just like you.

Richard

 

[hefftone]

I've made some progress, but still have some issues.

To replace to brass elbow, I used a 1/8" NPT Nipple (1-1/2" Long), out of the block into (the side of)a 1/8" NPT Female Tee. Out of what should be the bottom of the tee, a 1/8" to 1/4" NPT Reducer to accept the new oil switch/sender. Then the of side of the tee, which is actually up towards the hood, I capped with the 1/8" npt hex plug.....to use as a hook up point for an external gauge.

I also replaced the Fuel pump relay which had failed. So now I can start the engine, and unplug the fuel pump relay and it will keep running....as it should.

So here is some things I am curious about.
I shut off the engine....and the fuel pump kept running for about 5 seconds afterwards. That seems long....or does it mean I have awesome oil pressure?

Check gauges light is coming on......but after several minutes starts to dim and flicker slowly then turn off. Seems to do this most when it is very cold outside, and the engine has sat, usually overnight.

My oil pressure gauge still shows full pegged....always.

 

[someotherguy]

Typical for the pump to run several seconds after shutting the engine off. Nothing to worry about - normal. You think 5 seconds is long, try a truck equipped with the "hot fuel module" - runs like 20-30 seconds!

Check gauges light / gauge pegged - you replaced the sender right? What brand and part #?

Have you hooked up an external mechanical gauge yet to see what your actual oil pressure is?

I did read earlier you said it was ******* the gauge without the sender connected. Kind of a long shot here but do you have another dash cluster you could try? Those 88-91 moonie gauges aren't known for their long term durability. Many out there still working fine but a lot have crapped out. Your truck being a 90, skip one from a 91 as they're one-year-only (will work with minor rewiring at your dash harness connector) so a drop-in would be 88-90; you could also try just swapping the gauge itself as you can pop individual gauges out of the cluster. That would spare you from having to recalibrate the speedometer which the settings are built-in on the 88-91 clusters, instead of in the external DRAC module 92-95 use.

Richard

 

[hefftone]

Check gauges light / gauge pegged - you replaced the sender right? What brand and part #?

Yes. It is an Autozone Valucraft... not sure of the #, but it is a 3-pin...and longer than the 2-pin i removed.

Have you hooked up an external mechanical gauge yet to see what your actual oil pressure is?

No, but I plan on doing that.

I did read earlier you said it was ******* the gauge without the sender connected. Kind of a long shot here but do you have another dash cluster you could try?

No I don't have another cluster. My brother said that the gauge used to work right up until the engine replacement. Now that makes sense because the engine which came from a slightly older suburban (the older style, 89 I think) and had the 2-pin OP switch....I am assume the 3rd pin adds the OP sender. The engine still has the big sender located by the oil filter, with no wire connected.

EDIT: This was temporary/intermittent, i may have a bad connection somewhere...
I hate to jump off on another tangent, but I have noticed that as of today, my fuel pump is not priming at KEY ON. The engine takes longer to start. It seems that the FP wont kick on until the oil pressure switch completes the connection. I don't believe that was happening before, when I only had the new FP relay plugged in and no OPSS attached...

I just went out, and unplugged the OPSS...There was no prime and the engine would not start. I plugged the OPSS in again. Unplugged the relay, plugged it back in and tested a few times and had FP prime at KEY ON......frustrating

 

[someotherguy]

I'm starting to wonder if the wiring got damaged during the engine swap.

Richard