I put an L98in my '90 bird that had an L03. My oil pressure gauge stays pegged at 60+ psi. I'm wondering if I have the wrong oil pressure switch in it. The harness and ECM are from an '86 and the car is a 90. Any help?

 

That should be the right sender. v8 engines read 0 60 psi, and v6's read 0-80 psi, so as long as your going from v8 to v8, the sender shouldn't need to be changed.

The gauge being pegged on the high side suggests an open in the circuit. Possibly just not plugged in well, or the sender could be junk too. Since they're right there on the back of the block, it's not hard to crunch them against the firewall if your engine swings just the wrong way while putting it in.

See also https://www.thirdgen.org/techbb2/sho...hreadid=162812

 

Thank you much!

 

no prob...so did you find the problem?

 

You can't use a sender for a '86....you must use the one for the '90-'92 (read-- you can use the one from the L03).

 

Thats what I have done. I used the one from the L03 and spliced in the connector from the L03 onto the '86 harness because the '86 sender had a different plug. It stays pegged though

 

I'd try the 86 sender. It only takes a minute or two to change them out. I'd say it's more important that your sender matches your wiring than that it matches your engine, as long as the threads are the same and the sender screws in. Pressure is pressure, no matter what engine it's coming from.

 

I'm just wondering which one the gauge will recognize........?

 

my post before this one may have been incorrect, although there's nothing to lose by trying.

I can't find details on the 86 sender, but I know from personal experience that from 87-on the senders all work on the same principle. 0 ohms resistance for 0 psi, 90 ohms resistance for max psi (60 for v8, 80 for v6). The connectors may be different, but the function is the same (again, 87-on).

try putting an ohmmeter on the output terminal of one, or both of your senders. check resistance between sender terminal and ground with engine off, and then engine running.

Make sure you're plugging it in to the right sender. There is also an oil pressure switch on some cars.

 

Don't forget there were also 2 styles of senders. The ones up to, I don't know 88 or so were on the back of the block next to the distributor. 89-up (I'm guessing at the change years) had the intergrated oil sender/switch. While they both work the same but, they aren't easily switched unless both are in the block already.
A good way to see if it's just excessive oil pressure it to unhook the coil plug (and floor it to keep from flooding it or take the ECM fuse out at the battery) and watch the gauge while cranking the car briefly. It should give a fairly low pressure reading if the sender is working correctly.
Also, if this is a fresh built motor, expect the oil pressure to stay pegged for awhile until the motor & pump get a little wear to it.
Just some added ramblings...

 

When I went to the parts store, they had a pressure sender that had a 3-prong connector instead of two. Do you think this would the the pressure sender with the switch built in? If so, my harness only has a 2-wire plug which would mean that my sender and switch are two different units

 

Nasty, on the 86 harness, the oil gauge sender was a single wire unit that was screwed into the back of the block on the drivers side of the distributor. The 2 wire 'sender' in the block just above the oil filter is actually just the oil pressure switch and has no effect on the gauge at all. The switch is tied into the wiring for the fuel pump.
This will be the wiring setup you currently have on your car.

The 90 harness, that you did have, was an intergrated oil sender and switch (the 3wire unit). This did away with the sender next to the distributor.

What you will need (if you don't have it) is to get an 86 sender and find the single tan wire the leads to it. It has an odd shaped rubber boot on it as well to seal over the top of the terminal on the sender. Hope the helps clear up what you are looking for a little.

 

That helps alot. Thanx so much!

 

those oil press switches dont work worth a ****, because i had my oil pickup fall off of the oil pump and if i stoped hard i noticed the gauge went to 0 psi. i changed the sender down by the oil filter , (it is an 89 iroc 350 tpi) and it still did not cut the car off when the psi droped to 0. so they obviously are not programed to be quick. \

thanks
anthony

 

It is not designed to shut the car off with a loss of oil pressure.
The switch is only there so that if the f/p relay dies on you, you will still get juice to the f/p but, only after you build enough oil pressure to close the switch.

 

I don't think those switches are designed to cut off power in the event of oil pressure loss. Rather, I think they function the other way around, as a secondary means of activating the fuel pump when the pressure rises, should the primary pump relay fail.

 

doh...i got beat to the punch...

:P

 

ok i see then. so this could also explane extended crank times. i wonder if this could explane my sh!tty running car, (ie idles at 525 - 550 rpm, stummbles ect)????

i have replaced the cap and rotor with known good ones, fuel pressure regulator, spark plugs, put a new fuel pump on because old one craped out, checked f/p relay, installed a new intake manifold gaskets, plenum and runner gasketts, and the list goes on) i can not diagnose this damn car. i have had experienced techs llok at it and they are baffled. the scan tool does not show anything wrong. and there are times when the car feels like it just gained 50 hp, then it will sit for a few hours then run like crap again.

i am this close ( . ) to parking the damn thing and putting a built engine in it oh wait i am doing this to the 86 iroc i just got. must hang in there till summer to build blck 89 iroc up.

any of your thoughts would be helpfull because i have gone just about everywhere with this thing just shy of throghing new everything on it.

thanks
anthony

 

@zz.. If you hear the pump run for 2 seconds before cranking the car, the relay is most likely still working. A bad relay will delay the start but won't affect idle speed. Have you checked/set the minimum idle speed, TPS voltage, and/or timing lately ? Cleaning the IAC can somtimes help. Replacing the o2 sensor, fuel filter. Vacuum leak somewhere. Lots of small things overlooked can add to a large problem overall. It annoying to have to hunt stuff down to fix but, it's even more annoying to live with it day in and out while driving.
When I got my 91 a few weeks ago (though it's a TBI), it ran as if it had a bad fuel pump but, turned out to be the #5 plug wire was barely hanging onto the plug (thus a hesitant/jerky throttle) along with a previously replaced IAC that was not securely tightened made for a very crappy driver. After a full tune up (excluding coil) fluid & filter change, the car runs much much better.

 

i guess i was not thinking, it does come on before i start the car. the timing was set not to long ago. there are no vacume leaks. i have a new o2 to install, but have not got around to it, has a new fuel filter, and the tps is ok. i need to check the iac but it is a royal pain in the *** to do that. grr i need more time in the day.

thanks, it always helps to have a fresh mind to look at a problem

"as i look at an almost assembled puzzle for 3 hours trying to figure out where the last 50 peices go, a person walks by and puts all the pieces in the right place in 2 minuts. doh"

anthony