HELP! No oil pressure on LT1
Thread Starter
Instructor
Joined: May 2001
Posts: 238
Likes: 1
From: Conifer CO
HELP! No oil pressure on LT1
My '95 LT1 starts, runs fine, but shows no oil pressure. Oil and filter changed, no change. My '96 manual says the oil pressure sending unit is also a fuel pump switch. Would this mean the fuel pump would shut down if there was no oil pressure? Where on the engine is the sending unit located? I could go look but it's bitter cold in the garage. If the sending unit tests ok, what is the next step?
Safety Car
Joined: Mar 2001
Posts: 3,567
Likes: 0
From: Aurora IL
Re: HELP! No oil pressure on LT1 (Colorado Chuck)
Your guess is correct there is a saftey that prevents the fuel pump from remaining on if there is no oil pressure after start. You may have a bad sensor for the dash guage or the gauge it self may be bad.
Melting Slicks
Joined: Feb 1999
Posts: 3,261
Likes: 9
From: sonoma ca
Re: HELP! No oil pressure on LT1 (Colorado Chuck)
C/C,
The sending unit is located at the top rear of the engine. Its a Tee fitting.
The oil pressure sending unit is on the passenger side. You might want to check for pressure with a mechanical gauge. You might try wiggling the wires, you never know?
:cheers:
The sending unit is located at the top rear of the engine. Its a Tee fitting.
The oil pressure sending unit is on the passenger side. You might want to check for pressure with a mechanical gauge. You might try wiggling the wires, you never know?
:cheers:
Melting Slicks
Joined: Oct 2000
Posts: 2,726
Likes: 24
From: Freehold, NJ
Re: HELP! No oil pressure on LT1 (CAPN17)
Your guess is correct there is a saftey that prevents the fuel pump from remaining on if there is no oil pressure after start. You may have a bad sensor for the dash guage or the gauge it self may be bad.
Thread Starter
Instructor
Joined: May 2001
Posts: 238
Likes: 1
From: Conifer CO
Re: HELP! No oil pressure on LT1 (lou sylvestri)
Thanks, Lou. Maybe now I can find it before I freeze to death! We are not having weather good for either driving or working on Corvettes.
Melting Slicks
Joined: Feb 1999
Posts: 3,261
Likes: 9
From: sonoma ca
Re: HELP! No oil pressure on LT1 (Eric Fischer)
There are two sensors located in the Tee.
One is for the oil pressure & one is for the oil pressure sensor/pump switch. This is for an LT1. :cheers:
One is for the oil pressure & one is for the oil pressure sensor/pump switch. This is for an LT1. :cheers:
Drifting
Joined: May 2001
Posts: 1,297
Likes: 0
From: Edmond Oklahoma
Re: HELP! No oil pressure on LT1 (Eric Fischer)
I believe Eric is correct. The "fuel pump" portion keeps the pump running if there is oil pressure but it does not cut the pump off if there is no pressure.
As the others have said - time for a new sensor.
Mark
As the others have said - time for a new sensor.
Mark
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Thread Starter
Instructor
Joined: May 2001
Posts: 238
Likes: 1
From: Conifer CO
Re: HELP! No oil pressure on LT1 (lou sylvestri)
As soon as I located the sender and touched it, I knew that was the problem. Whoever put it in, broke it trying to get the socket on or off. It is a real PITA to replace, but I now show pressure. With the old sender removed, I packed rags around the tee and started the engine, which ran fine for at least the 3 or 4 seconds before I shut it off. I wanted to be sure the oil passage was clear, and to check the "fuel pump shutoff" theory. I don't think the oil pressure sender affects the fuel pump, but perhaps that is what the other switch on the tee is for.
QUESTION: When I fastened the electrical connector back on the sender, I heard a sound like a small motor running, even though the ignition was off. I started the engine, shut it off, and the sound continued for several seconds more, then shut down. What was that, and what does it do?
Thanks again for all the help. :)
QUESTION: When I fastened the electrical connector back on the sender, I heard a sound like a small motor running, even though the ignition was off. I started the engine, shut it off, and the sound continued for several seconds more, then shut down. What was that, and what does it do?
Thanks again for all the help. :)
Pro
Joined: Jul 2001
Posts: 652
Likes: 2
Re: HELP! No oil pressure on LT1 (Colorado Chuck)
Chuck,
I follow your thread with great interest as my LT1 has a similar prob, except it shows max pressure all the time. How the heck did you get that thing removed? did you use pliars, special tool, etc?
Marc
I follow your thread with great interest as my LT1 has a similar prob, except it shows max pressure all the time. How the heck did you get that thing removed? did you use pliars, special tool, etc?
Marc
Burning Brakes
Joined: Feb 2000
Posts: 927
Likes: 0
From: Saginaw TX
Re: HELP! No oil pressure on LT1 (Colorado Chuck)
Chuck, was the key on when you plugged up the sender? If so, the air pump for the AIR system may be running. Try and isolate where the noise is coming from. Just noticed that you were working on a 95 from a 96 manual. I just finished reading the tome Corvette Fuel Injection which covered the systems intricately from 82 to 01 and the 95 is a psuedo OBDII car and the 96 is the real deal. As such certain things function differently. That said, I believe it said that the electric air pump would run for 240 seconds when the Engine coolant temp was 60 degrees C. or below. Good Luck
[Modified by mash557, 9:01 PM 1/2/2002]
[Modified by mash557, 9:01 PM 1/2/2002]
Thread Starter
Instructor
Joined: May 2001
Posts: 238
Likes: 1
From: Conifer CO
Re: HELP! No oil pressure on LT1 (mash557)
Marc, I bought a special socket from the NAPA parts store. Problem is, there is no room to get it on and no doubt that is why the old sender was broke. I found that I could rotate the back end of the tee where the sender screws in towards the passenger side, which gave me room to get the socket on. I then had to push it back in order to attach the electrical connector which was another PITA. To remove and tighten the sender I used a wobble extension, which has rounded ends where it goes into the socket allowing you to be well off center. I have an old jeep where the oil pressure pegs itself, and I am sure it is because I have the wrong sender installed. Be sure you get the correct one for your car.
And if there is anything that requires maintenance, it is a helicopter! Fly one hour, work 10!
The ignition was turned OFF when I heard the motor noise. It continued with the ignition on and finally turned itself off. It just really surprised me to hear a motor come on when I plugged the sender in. The sender is a 3 prong switch, which I and others thought was for the fuel pump.
And if there is anything that requires maintenance, it is a helicopter! Fly one hour, work 10!
The ignition was turned OFF when I heard the motor noise. It continued with the ignition on and finally turned itself off. It just really surprised me to hear a motor come on when I plugged the sender in. The sender is a 3 prong switch, which I and others thought was for the fuel pump.
