20 Most Recent 1991 GMC Sonoma - Page 8 Questions & Answers

sorry but need to know if its a petrol or diesel variant

no it doesn't matter...the orange is +12vdc and the white is the "momentary" ground that is made with the opening of the doors , the switch, if one is up there, and the dome light switch on the dash instrument control.

change sprk plugs and wires

I am having the same problem. Looking for answer.

There could be an additional fuel pump located inside your gas tank. You didn't say what type of vehicle it is, but sometimes there are two fuel pumps, one is the pain in the **** inside the gas tank, the other is under the hood.

check the slave cylinder for low fluid

If you google it and click images sometimes you can get these for free

check your linkage you may have hit somthing and bent the linkage.

did you check the fuse and make sure you have a good ground.Also check with alight tester to make sure power is getting to the motor. use the switch to power it up.

sounds like you have a wire hooked up wrong some wires are crossed. Check your wire harness under the dash or by the batt/alt for bare wires that are contacting.

I had the same problem. Google your engine I had a 4.3. Click images for fiiring order you will find it. You can also click video for setting timing. I got mine running with this information. Just remember that there are two marks on the harmonic wheel one for TDC & BDC. Also you need 3 things air/fuel/spark. Make sure you have these before replacing parts it gets spendy. I got my whole distributer and spark module for 40.00.

you have a bad ground to the taillight units

You broke the low one way clutch. The trans will need rebuilt. The truck should be drivable if you take off in Man 1, shift to Man 2 at about 12mph, then shift to drive at about 27, then shift into overdrive at about 42.

Change charcoal canister

Sounds like the choke is stuck shut.

For 1991 GMC Truck S15 4WD 4.3L TBI 6cyl...

Engine Oil Type/Weight/Capacity

3539
Application:
Oil for use in temperatures above 39 degrees
Note :
Pennzoil Premium Motor Oil HD30

Application:
Oil for use in temperatures above 39 degrees
Note :
4 Quarts without filter change

VALHD30
Application:
Oil for use in temperatures above 39 degrees
Note :
Valvoline Premium Conventional 30 Motor Oil

Hope helps (remember rated this).

You may have a worn out O2 sensor or catalytic converter. Maybe time for a tune-up?? Is the check engine light on?