20 Most Recent 1990 GMC Sierra - Page 7 Questions & Answers

Sound like you might not have it timed correctly. If you just had the intake off you had the distrubutor out. Bring to #1 TDC on compression stroke and see if the rotor is pointing at the #1 post on your cap. If not your distibutor is not installed correctly. That is where I would start.

Sound like it could be a clog fuel filter, have you check it, if not remove and check to see if it's clog, replace it if bad, fuel filter is under your truck, on drives side, on inner frame rail.

Any dealership will be able to diagnose your truck's problem. Repair shop can also do this, but I would try the dealership first. Hope this helps! Please rate 4 thumbs up!

Check to see if all the ground wires are good and attached, might have left off the one that ground the engine to the body, check ALL connections positive and negative. if you need more help get back to me Thanks Ray

Low fluid? is this the 7.4l engine with hydro boost?

Lock cylinder needs to be replaced. It's kind of a pain to replace - steering column apart, etc... Most parts store carry replacement - note you will now have 2 keys for your truck - outside locks & ignition.

yes please replace the fuel filter,the fuel filter replace every 40,000 kilometers according to the factory specifacation.then buy a repair kit of the carburator to clean and replace gasket to prevent leaking of gasoline

MORE THAN LIKELY IF YOU LOOK UNDER THE HOOD AND START LOOKING YOU WILL FIND A HOSE OFF ,CRACKED OE BROKEN.

sounds like a classic vacuum leak, check the hoses at the base of the throttle body there are a couple in front and two larger ones in the back one of them could have cracked or broken causing an incorrect intake vacuum hence the lack of power and such

Check the earth connection between the engine and chassis.

If wires came off oil pressure switch or if switch went bad, it would shut down truck immediately. Your oil pressure switch performs 2 functions; oil pressure to gauge.light and it's also a safety feature that if you're in an accident or rollover, when oil pressure drops it shuts off power to fuel pump. I'd start there. The reverse is also a possibility, if fuel pump fails, truck shuts down = no oil pressure.

The Throttle Position Sensor is normally set from the factory and rarely if ever requires setting unless it is removed/replaced. GM product have a slot where the TPS is slid on and no adjustment is required.

can you jump starter at the starter. I'm sure it is a neg or positive cable that has lost contact. check ground cable,clean and tighten, check positive connection at starter and at terminal on battery

on the transfer case under the truck, there is a relay. both of my trucks have done the same thing and it was that simple problem. the wiring is on the drivers side of the case.

the sending sensor

Hi and welcome to FixYa!

As a first course of action please do check the spark plugs. It can be faulty which can make the car not to start for it's not burning fuel. Have it replaced if that's the case and plug wire replacement can be helpful too for better fuel burning.

Hope you find this information helpful enough and thank you for using FixYa! Have a good one!

front disc, rear drum

there are lots of issues with the pump it is rare to see the valving in the sector do that

Recheck as there is no code 18

Generally these controls go bad and nothing works. They are an imported item GM uses of course. The electronics short circuit and go completely dead. Best to find a used one that works for new ones are expensive