Oil pressure sending unit problems..

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bigsthedog

New member
SO i have a 1991 3.0 efi that seems to be having an oil sending unit troubles. Now I'm no mechanic but from when i bought the truck the oil pressure gauge was not working. I changed the oil with 10w30 and put a new filter on it. Thing runs beautifully. The Oil sending unit is on and attached which makes me think it is just shot out. Checked out the Instrument Cluster and its attached and the dash light for the gauge works. Any thoughts on what i should do? My speedo is also out but ive narrowed that down to needing a new speedo cable.
any questions or comments are appreciated.
 
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Could be several things here. First, do you know if its the correct sending unit installed? There were several different ones, depending on whether you had an oil light or and actual gauge. You should be able to test the gauge to see if its actually working or not.

Do you know if the gauge in the dash actually works? If you have an oil pressure gauge in yours and the previous owner put the cheaper sending unit for just a light and not the one for a gauge, the gauge will be completely fried and you'll need to get another cluster to fix it.

I'd first check to see if the gauge actually works by searching the 'net for testing a toyota sending unit. Knowing what the sending unit is sending to the gauge will help determine whether the gauge works or not. If it does, then test the sending unit to see if its sending anything out. If not, new sending unit. If its good, then I'd start checking at the cluster to see if you're getting the signal to the cluster.

RockAuto.com has the gauge-style sending units for 24 bucks plus shipping if you need to replace the sending unit.
 
So I just got done replacing the sending unit and nothing. I already tested the gauge cluster and it works.. So I assume it must be the wire?
 
So I've tested the harness, tested the gauge, and replaced the sending unit, and still nothing. I really hope it isn't my oil pump. Any ideas guys c'mon! I'm running on empty right now
 
Have you tried hooking up an actual mechanical gauge to the block to make sure you have oil pressure?

Hate doing this, as it makes a mess, but pull the oil cap and see if you're getting oil slinging all over the place. If you are, chances are the oil is getting pumped up to the upper cylinder heads and slinging around from the valvetrain. This WILL make a mess if it is working, so be prepared!

If you get nothing, then I would be very, VERY worried!

Found the page in the manual for testing the sender and gauge. I assume you have the online manual for the 88+ 4 runner? If not, search for the links, I believe it was posted here about 3 or so weeks ago, I posted the link to the manuals.

Look on page BE-30 in that manual for testing. It will tell you whether the sending unit is actually working or not.

How did you test the gauge itself? from the cluster or from the wire at the sending unit? Could be a break in the wire anywhere along the line if you only tested at the cluster. If you tested from the sending unit, then your unit is either not functioning or could be the wrong sending unit. There's something I read a while back on Pirate or toyotatech or somewhere (I really can't remember) about there being several different models depending on year/engine/model(sr5/dlx).
 
flyinhawaiian01 said:
Have you tried hooking up an actual mechanical gauge to the block to make sure you have oil pressure?

Hate doing this, as it makes a mess, but pull the oil cap and see if you're getting oil slinging all over the place. If you are, chances are the oil is getting pumped up to the upper cylinder heads and slinging around from the valvetrain. This WILL make a mess if it is working, so be prepared!

If you get nothing, then I would be very, VERY worried!

Found the page in the manual for testing the sender and gauge. I assume you have the online manual for the 88+ 4 runner? If not, search for the links, I believe it was posted here about 3 or so weeks ago, I posted the link to the manuals.

Look on page BE-30 in that manual for testing. It will tell you whether the sending unit is actually working or not.

How did you test the gauge itself? from the cluster or from the wire at the sending unit? Could be a break in the wire anywhere along the line if you only tested at the cluster. If you tested from the sending unit, then your unit is either not functioning or could be the wrong sending unit. There's something I read a while back on Pirate or toyotatech or somewhere (I really can't remember) about there being several different models depending on year/engine/model(sr5/dlx).
Click to expand...

I tested the gauge by touching it to a grounded wire.. It works.. I def have the right sender as well. I had it running with the cap open and it didnt make a mess.. So now im worried.. Im going to take it to a guy around the way who specializes in toyota and see whats up.. Hes a family friend so he wont rip me off.. Thanks for the help FlyinHawaiian!
 
Should be able to put a meter on the sending unit and see a resistance change between running (pressure) & not running (no pressure). Be careful shorting the wire to ground, it will fry your cluster gauge if you did not already do it.
 
bigsthedog said:
I tested the gauge by touching it to a grounded wire.. It works.. I def have the right sender as well. I had it running with the cap open and it didnt make a mess.. So now im worried.. Im going to take it to a guy around the way who specializes in toyota and see whats up.. Hes a family friend so he wont rip me off.. Thanks for the help FlyinHawaiian!
Click to expand...



That concerns me too! You should at least get some oil slinging around past that oil cap. How bad did the oil look on your last change? Do you know how many miles were on that oil?

Any bad gunk under that oil cap by chance? Trying to see if your oil is only slightly getting pumped around your engine. It doesn't take a lot to keep the engine oiled up enough to continue running, but it will get damaged over time.

Let us know what the mechanical gauge reads for you. It should be as follows:

Oil pressure:
At idle speed: More than 0.3 kg/cm2 (4.3 psi, 29 kPa)
At 3,000 rpm: (36 - 71 psi, 245 - 490 kPa)

That info is found in the manual too, page LU-2.
 
So just got a call back from my mechanic and he said my oil pressure is right on point, and that it could be my new sender I just installed(we grounded the wire to check the harness and gauge and they work.)
And he also said my speedometer doesn't have a Speedo cable and it's electric. Is that right for a 91?
 
Well, if there's no cable coming out of the transmission, and the rear of the cluster doesn't have a cable connection for it, its definitely an electric speedo.

Other than that though, I have no idea how else to determine whether yours had electric or cable. I can't tell which one came with electric and which came with cable, but they are interchangeable in a sorta weird way!

See what the cluster has, then change out the gear on the trans to match what your cluster wants. This would be the part (link grabbed from another forum!):

IMG_0828.jpg~original


Of course, if yours is just not working, and it did before (assuming the trans wasn't replaced with a different trans that had the other type of unit), could just be that part in the image above that's bad.

As for the oil sender, he could very well be right! I know I saw something about this once, the guy had to go through 3 different sending units before he found the "correct" one that worked with his gauge! Of course, I remember him saying it was the most expensive one that finally worked! Check with your parts guy and see if he has different ones listed.

At least the good news is that your pressure is good and you don't have to worry about burnin' up your engine!!!:D
 
Yeah well guess what I just threw a 40 dollar cheapo auto zone oil sender on and it worked haha. I'm so happy for that!
And I took my instrument cluster out and there is a cable hooked up.. I'm gonna go to toyota and get a new one tomorrow. Also just got a check engine code readout for intake air temperature sensor.. Could that be my slightly cracked emissions hose or that's most likely causing that do Ya think?
 
Hmmm, I dunno where the IAT is on the v6, but the 4 cylinder is inside the MAF. There's a little plastic thing inside of the intake side near the door that measures the temp, its not really replaceable without getting a complete MAF for the 22RE engine.

Good news is that you can clean it with throttle body cleaner if its super dirty. Change the tube too, no sense having it cracked and open to vacuum leaks.
 
So I coded it and the issue is coming up as 42. That is the VSS.. Where is the speed sensor on this thing and could that be why my Speedo is out? I get a check engine light going 65mph+ and it seems hesitant to wanna shift. But it only
Happens when I spike the rpms tying to accelerate at high speeds.
 
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