20 Most Recent 1991 GMC C1500 - Page 8 Questions & Answers

The common reason for this is no charge inthe system due to a leak.

Hello! Just because you changed an engine does not mean that something unrelated hasn't occurred... In the fuse box is the 10A fuse in the far left row...Third fuse down?....If it is that is the ECM ignition Fuse...Tracing from the ignition switch it is a Pink wire that goes to a 3A in-line fuse and changes color to Purple/White then on to the ECM...When the fuse blows is there battery on the Pink wire?...If not...Pull the blown fuse...Disconnect the main Battery terminal...Set multimeter to the X 10 scale...Place one lead on each side of the pulled fuse socket and the other lead to bare metal ground...Does either side read resistance to ground?...If it does turn the ignition key from off...To ACC,.. to start and finally hold on run...Does the ground go away in any of those positions? if it does I would suspect one of the ignition switch wires is touching ground...Hard to find...But if you alligator clip the meter in place and wiggle the ignition wires you may see it come and go...Indicating where you are moving the harness the bare wire is pinched to ground...However...If the movement of the key does not produce a change...Remove the fuse box...Flip it over... identify the wire on the fuse that blows and trace it with meter in-place wiggling as you move through the harness until you find the bare spot touching ground...An easier softer way is to identify the color of the wire that connects to the ECM IGN FUSE...It will be Red, or Purple/White and go to the ignition switch...Cut it on both ends and run a wire of the same gauge from point to point...Guru...Saailer I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

I just fixed one.There is a small pin that you can push out to remove the coupling that pushes into slave cyclider. Then you have to heat up silver soder or brazing that holds tube into square fitting that goes into slave. After removing do the opposite to braze in new tube. If you know were the line is bad cut it about 3 inches further away to make sure you have a good strong tube to splice from. You will need 2 compression fittings one to splice the one your adding and one for the original line. The fun part comes trying to bleed out air after its back together Takes at least 30 pumps between each opening of bleeder that's located on back of slave unit. And make sure that you never leave the resevour run low or dry on fluid while bleeding or your going to have to start over.You will need to keep adding fluid throughout bleeding process. Regular brake fluid is what is used for clutch. Good luck

firing order is 18436572 drivers bank 1 3 5 7, passenger 2 4 6 8

Faulty fuel pump.Check your fuel pressure it should be 9-13 psi with engine running.

You could possibly have a fuel injector that is sticking open in that cylinder.The only way to check this is to install a fuel pressure gauge and turn the key to the on position and check the pressure.It should stay between 60 to 66 psi and hold for at least 10 minutes or more.If it goes down the you could have an injector leaking or leaking internally in the tank.I checked service bulletins and found one for the fuel pulsator in the tank getting ruptured from the high percentage of ethynol in the gas.The bulletin number is 66-63-09.The part number is 25175836.This pulsator is updated to handle the high percentages of ethynol.Hope this helps.Good luck.

4.3L, 5.0L, 5.7L, 6.5L DSL Turbo VIN F or 6.5L DSL Turbo VIN S ??????????

Finding free repair manuals on vehicles is almost imposssible. Even finding downloadable repair manuals are hard. I have found that ebay motors has used copies for not to bad a price or ordering them on cd from the dealers.

Some fault codes or check engine light turn on there?

The most common reason for stalling on this engines is the fuel pump. You should have around 45-55 psi fuel pressure. If you can set up the gauge so you can see it and drive the truck at the same time, watch the gauge and see if the pressure dropsout when the engine stalls. You my also want to check the grounds on the back of the heads on the engine, a loose ground can also cause the engine to stall and shutoff.

Are you check wires at/from coil harnesses? Brokes could cause this effect. Also, keep in mind that a CKP (Crankshaft Position) sensor can cause a stall and it may not set a code. Most of the time when a crank sensor goes bad, the engine will stall and not restart until the engine cools down. It could be a wiring issue, a bad connection or loose connection. Try running the engine and wiggling the wiring around the sensors and grounds to see if the engine stalls or studders.

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The assembly sequence in which you set the crank gear dot at 12 o'clock and the cam gear at 6 o'clock (for timing chain installation) and then rotate the crank 360 degrees to bring the IP drive gear on the front of the cam to 12 o'clock for installation of the IP driven gear at 6 o'clock? That is the so-called "connect the dots" process to properly time a 6.2 diesel. -------- Click this link below for more details:-- http://howtobyme.blogspot.com/2011/09/1989-gmc-diesel-62-timing-gear-diagram.html ---------- This will help.Thanks.Helpmech.

There should be 2 rubber blocks in the wire harness down by the starter. These are fusible links and one kills power to the truck, the other kills power to the engine. Cut them out and splice the wires back together, one at a time of course. Old age will do them in on occasion, moisture gets in there. Use some "heat shrink tube" to cover the splice. It works much better than tape. Hope this helps.