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High oil pressure reading on my gauge???

WPS 73 Bronco

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Jan 12, 2023
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So I’ve finally got all my gauges working. Now the question is do I believe the oil pressure?
it starts at zero before I turn on the bronco. I turn the key on but don’t start it and it sits at zero. Then it slowly increases to 90 once I start it up.

thoughts?
 

DirtDonk

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Sure, lots of them! 😁😎
First, what weight oil are you using? And did you also use an additive?
Next, what are the readings on the other two gauges?
If temperature and fuel read high as well then you might have a misadjusted IVR.

So that’s a start at least.
 
OP
OP
WPS 73 Bronco

WPS 73 Bronco

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Loc.
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Fuel is reading correctly. Temp is About 180. The oil is actually at max dial, not 90.
not sure what the oil weight is as I’ve only had the bronco for 2 months.
 

DirtDonk

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Why was it replaced? New can be better, but not always.

You’ve had it but didn’t change the oil?
Do you know the previous owner? Buy from a shop or Bronco reseller that you trust?
You have at least checked the oil level and cleanliness?
When I bought my ‘71 it read 80+ psi on the gauge. Problem was it was just over 4 qts low at the time. When we added enough to get it to just above the low line, the pressure came down to about 65-70 psi.

Which is probably why I ask these kinds of questions.
 
OP
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WPS 73 Bronco

WPS 73 Bronco

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Jan 12, 2023
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Bought it from a dealership that did service the Bronco before I got it. The gauges didn't work, so the first thing I did was replace the IVR. Bingo, everything had life except the fuel gauge. The oil pressure pegged max right away. After evaluating the fuel gauge, I determined that the PO had bastardized the wiring on the electric tank solenoid valve. I purchased a new fuel tank switch, and wired the system up correctly. The fuel gauge worked. So now I'm just down to the Oil Pressure gauge. It pegs to max once the engine starts up, and never moves from that position.
 

66broncoCT

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Feb 6, 2012
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Does it peg the gauge with the key on but engine not running? That would indicate a wiring problem. If it only pegs while the engine is running it could the wrong sending unit in the engine for the bronco gauge.
 

Torkman66

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Take your Ohm meter and test the sending unit. Simply unplug the wire and use these numbers:
Oil
90 psi = 10 ohms
70 = 20
40 = 30

If you’re showing more than about 20 ohms, gauge is bad. If showing near 90, gauge is likely good.

Best way to test sending unit is to replace it with a new one.

If sending unit is good and gauge registering proper, then you have concluded that you have 90 psi. That’s not nessearilly a bad thing. Might have 20/50 zinc oil (Castrol) in it which is highly recommended for older motors. Let it warm up and see what it does.
 

Torkman66

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It does however sound like gauge is pegging which suggests a short. As noted prior, you would normally see it peg with just key on. But if there is an internal problem with the SU then it might only peg once some degree of oil pressure is present. Sending units are not very expensive. I’d test the ohms to check gauge and then replace SU. At least you would know those are good.
 

DirtDonk

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Take a peek at the engine where the sender is, just above the fuel pump.
Does it look like a small cauliflower, or a bell shape thing about an inch and a half tall?
 

DirtDonk

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When you check it out, if you're not sure, or it doesn't match my admittedly vague descriptions, post up a picture so we can all check it out.

Paul
 

DirtDonk

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You mean pressure sender.
And that doesn’t look like the correct one to me. I’ve seen that type before, but the typical standard one for a bronco gauge is much larger with a curved bell top.
None of that black plastic stuff.

Doesn’t mean that somebody doesn’t make one like that that’s correct, but it’s not correct in my experience.
Maybe others have seen and used one like that?
 
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