1990 GMC Sierra - Page 4 - Answered Questions & Fixed issues


To review, you have two temp sensors, one for the gauge on the dash and one for the computer. If you unplug the sensor for the computer the reading will be minus 30 degrees or over 300 which will make it very hard to start. Unplugging the sensor for the gauge would have no effect on the computer.
According to the wiring diagram, the wire for the temp gauge is green, and the wires for the temp sensor for the computer are yellow and black.

1990 GMC Sierra | Answered on Aug 24, 2012 | 2,586 views


coiuld need fuel filter replaced or maybe weak fuel pump. Can have it pressure tested to see if this might be the problem. Could also be dirty gas which some gas treatment might fix. These are the things i would check first being that you said all the sensors checked out...hope this helps and good luck..

1990 GMC Sierra | Answered on Aug 15, 2012 | 79 views


Stater more?? What does that mean?

1990 GMC Sierra | Answered on Apr 27, 2012 | 30 views


with the assumption its an automatic the following applies(if a manual youll need to remove the slave cylinder from the transmission, its located above the starter) 1.Disconnect the battery and place truck on jackstands if needed for clearance and remove the starter 2. Remove front and rear drivelines as well as speedo sender and and shift linkage (remove shift lever if manual and transfer case shift linkage if not push button, you should be able to just seperate the linkage from the ****** and transfer case and leave the linkage dangling) and any other electrical connections to ****** and transfer case (such as push button transfer case, and electronic automatic trannies) make sure to scribe a line or mark the drivelines in relationship to the yokes so they get installed in the same position for balance 3. Remove transfer case, this will take some of the weight off and make moving the ****** around much easier on you 4. Beggining with the top bellhousing bolt remove all but the bottom two bellhousing bolts (save those for later, one on each side) 5. youre going to need a helper for the next part unless you have a transmission cradle for your floor jack support the transmission with a floor jack remove the crossmember bolts from the frame or completely remove the crossmember from the equation,, either way works 6. remove the two bottom bellhousing bolts from earlier, the transmission is now free, you will have to wiggle it around some and **** it as sometimes the splines on the torque converter bind up, sometimes in low clearance applications you need to support the motor with hoist, remove the motor mounts and drop the motor slightly to get a better angle. sometimes the ****** will pop right off and sometimes you have to fight it a bit but thats the way it goes, just remember the ****** is heavy so be carefull if not useing a ****** cradle! hope this helps out, good luck. also i recomend buy a chilton service manual for any do it yourselfers, its only about 15 bucks and covers alot of stuff, such as removing the ******.

1990 GMC Sierra | Answered on Mar 13, 2012 | 436 views


Hello! The Mad Street #8362 is not for a seven pin, computer controlled engine...It is for a five pin distributor...I believe your engine has a seven pin connector...The correct distributor is a: MSD Ignition 8555Guru...saailer

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

1990 GMC Sierra | Answered on Feb 13, 2012 | 479 views


Sounds like an ignition module to me. (located inside distributor)

1990 GMC Sierra | Answered on Feb 04, 2012 | 148 views


Unfortunately, it sounds like you have a cracked block. To verify this, you can buy a test kit at most autoparts stores.

1990 GMC Sierra | Answered on Jan 25, 2012 | 93 views


If all was done correctly and your sierra is running fine it has to be your HVAC system blend doors not opening correctly...It is common for a lot of vehicles but mostly Dodge has this problem...These doors are inside the unit and they will break and not allow anything through or else stick open and allow everything through and not allow a change in air /heat blend...The quickest cheapest way to find out is to take it to a chevy dealer and describe your problem and only ask for a diagnosis...They will tell you if the actuator isnt opening the blend door or if the door is broken...It can only be done with a Tech II GM scanner..but ot is worth the money ...They make a quick fix which requires cutting the body of the unit and replacing the door or else replacing the faulty actuator..........This is true I hope this helps ...........Metalpoet

1990 GMC Sierra | Answered on Nov 03, 2011 | 336 views


Try another coil and mount it correctly. Check wires for power.

1990 GMC Sierra | Answered on Oct 27, 2011 | 305 views


Common problem. The drive shaft needs to come out and lube the splines going into the transmission. Nothing to worry about as they all do it.

1990 GMC Sierra | Answered on Oct 15, 2011 | 43 views


ring & pinion or spider gears in rear end

1990 GMC Sierra | Answered on Sep 17, 2011 | 79 views


if it is the one i am thinking of there are 2 doll pins that go through the bottom of the reservoir
you get them out it will pop right off

1990 GMC Sierra | Answered on Sep 15, 2011 | 108 views


Without a steady idle rate, its bound to act up when there s load on it cos with the fluctuation the idle might be too low at some point. Things to look at will be the idle control solenoid, throttle body, MAF sensor, check if carbon tracked then clean out throttle body with carbeurator cleaner.

1990 GMC Sierra | Answered on Sep 11, 2011 | 157 views


if master replaced sounds like air still in lines rebleed the brake lines start with passenger rear than driver rear -pass front -than driver front last..before bleeding check rear brake shoes are adjusted correctly

1990 GMC Sierra | Answered on Aug 10, 2011 | 453 views


The hi beams should be on the turn signal switch you should just pull it back towards you and most GM radios have to be turned off then you hold the seek or volume button down and it will start changing the time and some had a real small HOUR and MIN button that had to be pushed with a Pin .

1990 GMC Sierra | Answered on Jul 02, 2011 | 120 views


Freon has been banned, so unless you stockpiled a bunch of it you'll need to have the A/C converted to use freon free refridgerant. You may be able to get instructions here:

register for free at www.autozone.com Once registered you'll have access to repair and shop manuals for virtually any car or truck. All the data and diagrams you need now or may need in the future will be a couple of mouse clicks away.

1990 GMC Sierra | Answered on Dec 09, 2011 | 204 views


It is call a Throttle Body Injection, that is why you see wires and electrical components. You stated that fuel came out of the fuel line with little pressure. It could be that the fuel pump is weak, bad injectors, or fuel pressure regulator. Have the fuel system tested to determine what is the exact cause.

1990 GMC Sierra | Answered on Jun 22, 2011 | 255 views


Welcome to Fixya
Engine that wont start might fall to a lot of contributing factors e.g fel distribution, dead battery, alarm problem. Could yo give me more information on what is happening when you turn key to start position? Are you hearing click sound, engine cranks etc... Here's a link/guide for you to detect and resolve common issue for engine NOT STARTING.
Please reply to this email if you have further questions.
Thank you for using Fixya!

If you need further help, reach me via phone at https://www.6ya.com/expert/elixirjose_00375ea24bd8141b

1990 GMC Sierra | Answered on Jun 14, 2011 | 116 views


seddy29732_3.jpg I hope these instructions match your model.


  1. Lower the tailgate.
  2. Remove the lamp assembly retaining screws.
  3. Pull the lamp assembly from the truck and disconnect the wiring.
  4. Remove the bulb holder fasteners.
  5. Remove the bulb(s) from the lamp.
  6. Install the bulb, connect the wiring and install the lamp.

seddy29732_4.jpgseddy29732_5.jpgseddy29732_6.jpg

1990 GMC Sierra | Answered on Jun 03, 2011 | 193 views


There are two hoses going to the core, those two hoses get removed from the heater and connected together....

1990 GMC Sierra | Answered on Jun 02, 2011 | 241 views

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