90 GMC Safari Low oil pressure readings


Old 06-07-06, 08:25 AM
Thread Starter
Join Date: May 2001
Location: Just outside Vancover Canada
Posts: 20
90 GMC Safari Low oil pressure readings

Good Day,

I have a 1990 GMC safari. 4.3 ltr fuel injection, automatic.
My problem is that the oil pressure guage reads low oil pressure 90% of the time. When I start the vehicle the guage goes to 3/4 of maximum for a couple seconds then back down to 1/8 It remains at 1/8 for the duration, accelerate, normal speed, always at 1/8. About once a week when I start the vehicle it goes to 3/4 at start, then works as it "should" fluctuation to 3/4when accelerating or staying at 1/2 when at normal speed.

The vehicle runs fine, no noises, oil level is ok, no oil leaks. When I changed the pcv valve three months ago the oil pressure guage started working well for a week then went back to its low 1/8 above zero state. At last oil change I used (forgot the name) the stuff you put in the oil, run it then drain it, in theory it gets the extra gunk out of the engine, no effect on low oil pressure reading. The air intake had a lot of gunk in it so I used carb cleaner to clean it, no effect.

The motor was replaced with a rebuilt one five years ago. I am wondering how to tell if the guage has failed, or an oil sending switch, or if it indeed has low oil pressure and how to correct or tell.

Your advise is greately appreciated.

Sponsored Links
Old 06-07-06, 05:10 PM
Pendragon's Avatar
Join Date: Jul 2002
Location: USA
Posts: 1,835
Sounds like a sending unit (or the wiring to it).

A good shop will have a real oil pressure gauge they can hook up as well.

Sending units are typically not an expensive part, the last one I bought was less than $10.
Old 06-07-06, 10:02 PM
Join Date: Feb 2006
Posts: 361
Repace oil sending switch unit as thay fail alot on GMS.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Display Modes