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Question about LT1 Oil Pressure Sensor / No Start...

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I'm still working on getting the LT1 to run for longer than a couple of seconds. I've tested everything (according to the LT1 no start document) and have power to the places I should. What I believe is happening is that I'm not getting the signal needed from the oil pressure sensor at the back of the manifold that triggers the fuel pump to kick back on - thus the car runs out of fuel almost immediately.


The car has a speartech harness, and on the harness, the one wire coming off of the oil pressure sensor (tan) is designated by speartech for an oil pressure gauge. I have the wire going to my autometer gauge, but due to the fact that the dash is out getting restored, the gauge is not hooked up.


What I'm wondering is, should the gauge be hooked up this way? If so, how is the PCM getting the signal to kick the fuel pump back on?


Any thoughts?


Thanks in advance.



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Do you have the JTR manual?

If so there is a section it in describing the use of a Chrysler oil pressure switch. Read that section and you'll understand why the fuel pump is not kicking back on.

I don't know how your harness is wired or the setup of the F-body pump relay but in a B-Body setup there is an oil pressure switch wired in parallel with the PCM to the fuel pump relay. The PCM can control the relay and uses it to prime the system when the key is turned on but after that the oil pressure switch closes the fuel pump relay unless the oil pressure drops below a certain point.

I have the pressure switch and an original Datsun oil pressure sender connected to the port at the back of the intake manifold. I used a T-fitting just as the JTR manual describes. You will have to do something like this unless the f-body PCM accepts an oil pressure input signal (I don't think it does) from your sender.


Hope this helps.


One way to verify this is actually your problem is to "hot" wire the pump so it stays on all the time, then start your engine.



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I am also running 2 oil pressure sensors. The stock LT1 OP sensor goes to the PCM and the other is plugged into the threaded fitting just above the oil filter and is wired to the dash gauge. I am using the LT1 computer to control my fuel pressure relay.

I have not tried unplugging the stock sensor from the LT1 PCM to see if it will actually cause the fuel pump to shut down.... I thought it would.



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Grumpy: Thanks for the post - I read through it - very good info.


Jody: I'm going to run a setup similar to yours. Problem is, Jon over at speartech disconnected the wire for the oil pressure sensor from the PCM, so I'll have to go back and try to trace it to its origin. Hopefully I'll find the wire is snipped somewhere in between.


Thanks again for the help.



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I'm pretty sure my sensors are wired different that Jody's. I know the sender at the back of the intake goes to my guage becuase I ohmed the wiring and had to replace it to get the gauge to work. I did not rewire the engine harness so I can only assume the sensor at the oil filter is going to the PCM. The sensor behind the intake breaks very easily during engine install so maybe your's is bad. Mine looked good but when I checked it with an ohm meter is read shorted. Oh yeah that was a brand new sensor too!

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