2.8L rebuild in a 1985 4x4 Blazer

[Baja Blazer 85]

You could always reroute the AIR injection into one of those cats with the AIR tube on the side to get around it. The oil pressure switch... you could probably get a sender like any of a majority of the 60v6 cars have. It's a 3 wire deal. It has a sender for a gauge in it, and a switch to power the fuel pump if for some reason the ECM output for the fuel pump quits. I would need to see a schematic or read a bit more on it to be sure though.

I still dont really understand what an oil pressure switch is. Is that just another term for an oil pressure sending unit? and if so, cant I just use the old one off the 2.8?

Stop worrying! You don't need anything you don't already have. The only reason you need the electric pump is because there is no fuel pump mount on the engine block. But all you need is one of the hundreds of electric pumps designed for a carb'd engine.

Haha okay I'll try. I completely understand the fuel pump part now. I just want to be totally sure that I dont run into any big obstacles during this project since its my daily driver.

And once again, I really want to show my gratitide for all the help you guys have provided me with. I've also looked over a few instruction manuals and build threads and I think I got this down for the most part.

[pocket-rocket]

An oil pressure switch operates sort of like a dummy light oil pressure "sensor". When an oil pressure switch for a dummy light gets enough pressure, it opens the contacts (think light switch off) to turn the oil light off. In the case of the 60v6 world, it works opposite of that. When it gets enough pressure it closes the contacts (turns the light switch on) to power the electric fuel pump in case the ECM fuel pump control dies- so you can still get home. I haven't looked into the HT 3.4 swap, so I may be wrong, but knowing how GM has done the EFI systems, this is what I'm thinking the oil pressure switch is for. Don't take offense to this post, I'm not trying to make it or you sound dumb, I'm just trying to explain it as best and simple as I can in hopes you know what I'm talking about.

[WrathOfSocrus]

When it gets enough pressure it closes the contacts (turns the light switch on) to power the electric fuel pump in case the ECM fuel pump control dies- so you can still get home.

I believe its the exact opposite of that. It turns off the fuel pump after so long a period without fuel pressure in the event of catastrophic failure/collision, or if the engine has run out of oil to prevent the engine from locking up.

[Baja Blazer 85]

Oh, I think I get it. So instead of having an oil pressure sending unit hooked up to an oil pressure gauge (like on my Blazer), its an oil pressure switch, hooked up to a warning light on the dash (like on modern GM vehicles). It also acts as a safety device and shuts off the fuel supply when the pressure gets dangerously low.

I'm assuming I will not need this. My the oil pressure sending unit from the 2.8 can take the place of the required oil pressure switch.

Don't take offense to this post, I'm not trying to make it or you sound dumb, I'm just trying to explain it as best and simple as I can in hopes you know what I'm talking about.

Oh dont worry abou it man! Although I do know a thing or two about cars, Im also aware that I dont know everything. Posts like yours are very helpful, and the bank of knowledge on this site is literally priceless. I cannot imagine how far over budget I'm gonna go if I don't know these things going into the project.

[pocket-rocket]

I believe its the exact opposite of that. It turns off the fuel pump after so long a period without fuel pressure in the event of catastrophic failure/collision, or if the engine has run out of oil to prevent the engine from locking up.

Actually, it's not a safety/engine damage prevention device. It's been explained to me that it's there just in case the ECM stops providing power to the fuel pump meaning it's wired in parallel with the ECM, not series (to tired and lazy to bust out my Helms at the moment). Next time I fire up the 92, I'll unplug mine and see if it continues to run.

[geoffinbc]

Yup it is wired in parallel and will provide power if your ECM controlled fuel pump relay craps out. The engine will run even if the oil pan is bone dry.

[Baja Blazer 85]

I'm not even gonna bother buying an oil pressure switch then, I'll just use the oil pressure sending unit from the 2.8. That will work, right?

As soon as I'm done with the spring semester, I'm going to look into my funds and income, and unless theres anything else I need to know the project is a go.
Thanks again for the support guys!

[geoffinbc]

No you wont need a different oil pressure sending unit.