Oil Pressure Shut Down
Thread Starter
Racer
Joined: Dec 2004
Posts: 427
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From: Albuquerque New Mexico
Oil Pressure Shut Down
Hey guys. I'm running a 96 LT4 with a Procharger. When I am racing and run the car near red line it shuts down and the oil pressure drops out. The car will not turn back on until the oil pressure recovers which usually takes about 30-40seconds. It's mind numbing to think the car could shut down at any time. It didn't happen during tuning. My oil is 5w-30. I've been told by some racing buddies to switch to 15w-50 and replace the plugs with a smaller gap. This isn't a symptom of spark blowout from the supercharger right?
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
It sounds like you're hitting a rev limiter of some sort. If the engine is still turning, whether it's under power or not, then the oil pump is still turning. We have no way of knowing what rewiring may have been done to the car, but with a stock system and a functional fuel pump relay, oil pressure has nothing to do with the ability of the engine to start or run. Maybe trouble shooting of the fuel pressure relay is in order.
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Drifting
Joined: Mar 2005
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From: GA
Actually a high volume pump may be the cause of the oil pressure loss. It is emptying the pan very quickly and no oil has had a chance to get back down there before you loose pressure.
There are a couple of ways around this if you have a HV pump and want to keep it. First is a pan with 2 qts more capacity and second is an oil accumulator. This device holds oil (2 qts usually) under pressure, when the engine's oil pressure drops below a set point the accumulator will release its pressurized oil into the engine and prevent starvation. When the iol system recovers, the accumulator is automatically refilled with the extra oil.
There are a couple of ways around this if you have a HV pump and want to keep it. First is a pan with 2 qts more capacity and second is an oil accumulator. This device holds oil (2 qts usually) under pressure, when the engine's oil pressure drops below a set point the accumulator will release its pressurized oil into the engine and prevent starvation. When the iol system recovers, the accumulator is automatically refilled with the extra oil.
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Originally Posted by mash557
Just a thought, does this have a stock oil pump or high volume. You could be sucking the pan dry, which would trigger the low oil pressure switch.
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Drifting
Joined: Mar 2005
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From: GA
Originally Posted by drochau
I'm not very familiar with oil acumulators. What's a good one and what do I need for the install?
Race Director
Joined: Sep 2000
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From: The Top of Utah
Originally Posted by mash557
If the low oil pressure switch does not shut down the engine then what is it's purpose?
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Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Originally Posted by drochau
So which should I do first? The accumulator or the oil pan?
You've made a comment that is puzzling. "The car will not turn back on until the oil pressure recovers which usually takes about 30-40seconds.". How does the oil pressure recover, to "turn back on" if the engine isn't running (turned on?)?
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Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
In my schematic, circuit 120 is the power wire to the fuel pump. Running backward, it goes from the pump, through the body connector to the fuel pump fuse. The circuit number changes at the fuse. From the fuse it it becomes circuit# 458 and it goes through the I.P. connector and connects to terminal 17 of the ECM AND has three other feeds. One is from terminal "G" of the ALDL, the second is from terminal "A" (the 12 volt output) of the fuel pump relay, and the third is from the N.O. oil pressure switch. Circuit# 458 allows for the simultaneous powering of the fuel pump from three independent sources. Had you given your schematic more than a cursory look, I wouldn't have had to explain all that. It was right in front of your nose all along.
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Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Originally Posted by CentralCoaster
So you can ground a pin on your aldl to turn on the pump, useful for emptying the tank. (or do you have to put 12v to this pinout?)
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Burning Brakes
Joined: Feb 2000
Posts: 927
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From: Saginaw TX
And again you didn't answer the question!! What does the ECM do with the circuit. I can read a schematic and it seems that the ECM "could" do exactly as I said. None of my Helm's manuals gives any of the logic of the ECM. I have seen newer GM cars basically shutdown due to no or low oil pressure.
But we digress, the original problem is car stumbles and doesn't recover for 30-40 seconds. Most rev limiters should not take that long to recover.
drochau, I hope you get it figured out.
I'm done here. I really don't like being talked down to. CFI-EFI your sarcasm is really not needed or helpful.
But we digress, the original problem is car stumbles and doesn't recover for 30-40 seconds. Most rev limiters should not take that long to recover.
drochau, I hope you get it figured out.
I'm done here. I really don't like being talked down to. CFI-EFI your sarcasm is really not needed or helpful.
Team Owner
Joined: May 2002
Posts: 24,337
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
That wire is feedback to the ECM for "fuel pump low voltage" code 54. Probably one of the rarest codes, considering it has two power sources.
It's only mentioned in the code diagnostic section of the manual.
It's only mentioned in the code diagnostic section of the manual.