1991 gmc Sierra 5.7


Asked by Apr 07, 2014 at 01:53 PM about the 1989 GMC Sierra

Question type: Maintenance & Repair

Since my last oil change my oil
pressure isn't building, it used to sit
on 30psi now it barely reads on the
dial, any advice on the problem?

2 Answers


Well I wouldn't run it until you find the problem. You can try replacing the sending unit. How is the oil level on the dipstick. Did you change it or a shop.

1 out of 1 people think this is helpful.

Personally I would check the pump first but I have tools and equipment to do that. To test the oil pressure sending unit I use compressed air and a regulator. Pull the unit out attach the air and plug it back into the truck. Pressure up to a known pressure on a gauge and confirm the reading on the dash. If your sending unit is fine it is either the pump/pressure regulator or engine damage causing the low pressure. Start with the sending unit and we'll go from there.

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