Hey, I was hoping that someone could help me out on this one. I have
an 88 GMC 1500 with 166k. I bought it a few months ago. A few weeks
after I bought it I was driving and everytime I would hit the brakes
or let the engine idle, the check guages light would come on due to
the oil pressure dropping off to Zero. I figured maybe it was a bad
connection at first. I gave the engine an oil change and the problem
seemed to go away for a bit. Then after a few weeks, same problem
again. Only when I idle or hit the brakes taking power away from the
engine. As soon as I hit the gas, the oil Pressure comes back up
again. It used to run at about 100 Kpa. Now it seems that the oil
pressure is running a lot lower, and when I take my foot off the gas,
the oil pressure drops to zero. When I hit the gas again, sometimes it
doesn’t even come up. Does this sound like a bad pump, guage, faulty
wiring, or Worse? I don’t know these engines very well, so I am asking
for help. It seems also when I’m running it for a while and the oil
pressure is up again the check engine light will come on for about
20secs. then extinguish, this has only happened over the last couple
days. Anyone know how to get the codes of this thing. Any help would
be appreciated. Thanks

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In article <1208241_e7bc72092cc084caa345945a3c8ea291 (AT) autoboardz (DOT) com>,
vader <none (AT) 000 (DOT) com> wrote:

I'd be inclined to replace the sending unit.

Not related to the oil pressure reading.

Turn the ignition on, jumper pin "A" to pin "B" in the ALDL, the check
engine light will flash out a binary two digit code, i.e.,
blink <pause> blink blink is a code 12
blink blink blink<pause> blink blink is a code 32

Since the problem went away after an oil change, I'm thinking a bad brand of
oil. Years ago, a mechanic friend of mine said he had seen this with
Valvoline. My last truck had a nasty piston rod knock, only Castrol would
quiet the rod knock for more than two days after an oil change.

Please, try the oil change again. Use Castrol, and see if that helps.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"vader" <none (AT) 000 (DOT) com> wrote

Hey, I was hoping that someone could help me out on this one. I have
an 88 GMC 1500 with 166k. I bought it a few months ago. A few weeks
after I bought it I was driving and everytime I would hit the brakes
or let the engine idle, the check guages light would come on due to
the oil pressure dropping off to Zero. I figured maybe it was a bad
connection at first. I gave the engine an oil change and the problem
seemed to go away for a bit. Then after a few weeks, same problem
again. Only when I idle or hit the brakes taking power away from the
engine. As soon as I hit the gas, the oil Pressure comes back up
again. It used to run at about 100 Kpa. Now it seems that the oil
pressure is running a lot lower, and when I take my foot off the gas,
the oil pressure drops to zero. When I hit the gas again, sometimes it
doesn't even come up. Does this sound like a bad pump, guage, faulty
wiring, or Worse? I don't know these engines very well, so I am asking
for help. It seems also when I'm running it for a while and the oil
pressure is up again the check engine light will come on for about
20secs. then extinguish, this has only happened over the last couple
days. Anyone know how to get the codes of this thing. Any help would
be appreciated. Thanks

--
Posted at author's request, using moderated http://www.AutoBoardz.com
interface
Thread archive:
http://www.AutoBoardz.com/88-GMC-1500-troubles-ftopict248489.html

On Sep 4, 2:08*pm, "Stormin Mormon"
<cayoung61**spambloc... (AT) hotmail (DOT) com> wrote:
I'd also try a thicker viscosity like 20-50.
jimmy

vader <none (AT) 000 (DOT) com> wrote in news:1208241_e7bc72092cc084caa345945a3c8ea291
@autoboardz.com:

----------


This is a sending unit problem. Not sure what motor you have, but the 5.7
has it on the drivers side of the motor with a little 'Whitch' hat looking
thing over it to protect it. It spins off, and is easy to replace. There
is a pin hole inside the unit that is easy to clog, and the reason
for the low pressure reading.


HDS