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OPS or Oil Pressure Switch

WarWagon said:
These are a cakewalk to do vs. a starter or PS pump. Get the Leslie tool (socket) that fits it. It's on the back of the engine - the intake manifold isn't in the way. A creeper that is made for you to lay over the engine helps, but, I am too cheap to get one.
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If I had concrete in my shed, I'd have one of those over top creepers
 
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Will L. said:
Fuel Hose has ratings set by sae- Standard for Automotive Excellence. The number all stand for things but idk what they are. I learned it once, but then had to remember what 6 people wanted for lunch one day and the brain had to dump some memory...
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Aside heat, pressure and permeation ratings there are problems with UV radiation and OZONE when it comes to fuel/coolant hose failure. A good fire sleeve can extend temp exposure around exhaust and turbine housings.

Refresher: https://www.hemmings.com/blog/2014/12/05/tech-101-fuel-line-hose-what-you-should-and-should-not-use/
 
I had very similar results from my ffb from walking j must have bought that 8 years ago and when I swapped that engine into different truck it was in bad shape.
 
side note what got me to this thread, just spent 20 min looking and feeling around on back of my 96 looking for OPS (my other engines are pre 96 even in my 00). Did not remember that some are under the intake, did a search and here I am. I need to replace mine since it wont run the lift pump, has been wired to keyed on power since I got the truck haven't bothered to look into till now
 
What is this that Is on the frame rail near the LP found some broken wires but honestly have no idea what this is for.
 

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that's interesting. I guess I just figure that was the case since the lp is wired to power out of the fuse panel under the hood by one of the previous owners, they did put an inline fuse. I wonder why they would have cut the wires and wired it hot?
 
So is lp controlled by the ecm then?

Also I figured out what the mystery part is. Found a number on it so I googled it and it's part of the airbag system
 
My understanding is that it's kind of a combo system, and that even if the ops fails the pcm still is sending a signal. I know the OPS you is still working on my 99 as I can hear the LP run after I shut off the engine.
 
chevyCowboy said:
side note what got me to this thread, just spent 20 min looking and feeling around on back of my 96 looking for OPS (my other engines are pre 96 even in my 00). Did not remember that some are under the intake, did a search and here I am. I need to replace mine since it wont run the lift pump, has been wired to keyed on power since I got the truck haven't bothered to look into till now
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Do you have an AC Delco OPS in there now?

Do you have juice coming off the OPS? If so, you should be able to do Leroys lift pump relay upgrade. Often times you can do the upgrade and be back running. Even with an OPS that will not run the lift pump on it's own. They usually have a enough juice to trigger a relay
 
I guess first thing I need to do is hook the wires up to the factory wiring and see what is going on. Can you use a jumper to power the lp from the ops plug on the 96+ trucks the same as on the older ones?
 
chevyCowboy said:
I guess first thing I need to do is hook the wires up to the factory wiring and see what is going on. Can you use a jumper to power the lp from the ops plug on the 96+ trucks the same as on the older ones?
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There should be a wire by the firewall - by the underhood fuse box - with a spade connector - that when powered should run the lift pump.

I mount a permanent fused toggle switch there for diagnostics and bleeding purposes. I come right off the studs on the underhood fuse box
 
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