Something Annoying on my 70 Riv

[cars of chaos]

Hi All, just got my 2nd Riv, a 1970. I need a little info about something the previous owner told me. He told me that if the oil pressure is low, that the Riv will automatically cut out the fuel pump so that the car won't start. This was a safety attempt done by Buick so that you wouldn't blow out your engine if you had no oil or no oil pressure. Anyway, my Riv turns over no problem, but won't start, so I'm wondering if anyone has heard of this oil pump/fuel cut off thing and if that could be the case?

[Guest DRM500RUBYZR1]

Hi All, just got my 2nd Riv, a 1970. I need a little info about something the previous owner told me. He told me that if the oil pressure is low, that the Riv will automatically cut out the fuel pump so that the car won't start. This was a safety attempt done by Buick so that you wouldn't blow out your engine if you had no oil or no oil pressure. Anyway, my Riv turns over no problem, but won't start, so I'm wondering if anyone has heard of this oil pump/fuel cut off thing and if that could be the case?

I doubt that VERY much.

I have a 70.

My oil pressure sensor failed, invoking the oil pressure light, yet the car continued to run fine until I shut it down as a precaution.

Methinks he pulls your leg, or is somewhat "uninformed" to be polite.

Check for fuel pressure and delivery to the carb.

If none; bad pump or circuit / ground or clog.

If pressure, then look for other causes.

Let me know how you progress.

Marty

[Sweepspear]

Hi All, just got my 2nd Riv, a 1970. I need a little info about something the previous owner told me. He told me that if the oil pressure is low, that the Riv will automatically cut out the fuel pump so that the car won't start. This was a safety attempt done by Buick so that you wouldn't blow out your engine if you had no oil or no oil pressure. Anyway, my Riv turns over no problem, but won't start, so I'm wondering if anyone has heard of this oil pump/fuel cut off thing and if that could be the case?

I doubt that VERY much.

I have a 70.

My oil pressure sensor failed, invoking the oil pressure light, yet the car continued to run fine until I shut it down as a precaution.

Methinks he pulls your leg, or is somewhat "uninformed" to be polite.

Check for fuel pressure and delivery to the carb.

If none; bad pump or circuit / ground or clog.

If pressure, then look for other causes.

Let me know how you progress.

Marty

I also own a '70.

The fuel pump on the '69 & '70 Riviera is switched at the oil pressure sending unit. Without oil pressure ( below 3psi ) the pump will not operate.

It is partly a safety in case the car is in an accident and the engine dies, but the key is still in the on position. You don't want the pump to continue pumping fuel.

Since there is little to no oil pressure present when you attempt to start the car, the sending unit is bypassed and the pump energized when the key is in the crank position.

There is an often overlooked in-line fuse in the wiring harness, in the area above the power brake booster. It is a dark blue wire.

Check there also.

Edited August 29, 2013 by Sweepspear (see edit history)

[Guest DRM500RUBYZR1]

Intriguing.

So that would mean my pressure had to be > than 3 PSI, yet low enough for the sending unit to initiate the low oil pressure light.

Clearly the pressure was above 3 as it was a failed sending unit, not a genuine lack of pressure.

Puzzling then as to why it did not shunt the pump.

I have no reason to doubt that what you say is correct, just cannot reconcile that with what occurred when my sending unit failed.

Not only did it continue to run, but even after being towed to the garage, it then cranked and started even though the oil pressure light came on and remained on. No short in the light circuit, as a replacement sending unit cancelled the pressure light.

Where then do the two circuits come together, maybe that is where something is amiss in my case.

My car was built in December of 69, could there have been a production change?

[cars of chaos]

Hi All,

Yeah I agree that I think my seller was mis-informed on the fuction of this whole setup. I want to make sure that i point out I am NOT getting an oil pressure warning light at any time (other than right when i turn the key for the first time to start the car, when all the idiot lights turn on for a moment, of course). I'm going to start with the basics and see if its a clogged fuel filter, and work backwards (or forwards, as it may be) from there.

[Sweepspear]

Intriguing.

So that would mean my pressure had to be > than 3 PSI, yet low enough for the sending unit to initiate the low oil pressure light.

Clearly the pressure was above 3 as it was a failed sending unit, not a genuine lack of pressure.

Puzzling then as to why it did not shunt the pump.

I have no reason to doubt that what you say is correct, just cannot reconcile that with what occurred when my sending unit failed.

Not only did it continue to run, but even after being towed to the garage, it then cranked and started even though the oil pressure light came on and remained on. No short in the light circuit, as a replacement sending unit cancelled the pressure light.

Where then do the two circuits come together, maybe that is where something is amiss in my case.

My car was built in December of 69, could there have been a production change?

Sounds like your old sending unit failed in a way that falsely triggered the light, even though actual oil pressure was fine?

Edited August 29, 2013 by Sweepspear
sp (see edit history)

[68RIVGS]

A bud with a mid '80s EFI S10 PU had a 'no start' condition, caused by a blown fuse somewhere in the oil pressure wiring circuit.

It took three guys, with three different shop manuals, to locate and replace that blown fuse.

Started right up after the fuse was replaced, and a short in the wiring was repaired !!

[cars of chaos]

Sorry for the delay guys I've been really ill the last few days. Anyway, it turned out to be the positive battery cable. Looks like it had been hooked up for quite awhile so I unhooked it from the battery, used some sandpaper to clean up the terminal connection, then I found a spot where it has some exposed wire and taped that up with electrical tape and now the car starts up fine!