No power to IP/No start

[KidKodiak]

I've been racing over the past few days to get a 1985 GMC 3/4 ton suburban to start before Michigan winter strikes. It cranks just fine, but won't fire. Glow Plugs are getting power, I changed the fuel filter on the firewall, bled air out of that filter. Fuel is pumping out of the filter, but no fuel is coming out of the IP. I tested and no power to IP. Any advice to someone working on their first 6.2?

[Robyn]

The large pink wire on the IP is the power wire. Trace it back and see whassup. Could be a fuse or possibly the ignition switch.


Good luck

Robyn

[KidKodiak]

I think we forgot to turn the key forward because today I retested and there is definitely power going to the injector pump. So if there is power getting to it, does that rule out the fuel cut-off switch? And does this most likely mean my fuel injector pump needs to be replaced?

[Subzilla]

USUALLY, injector pumps don't die that suddenly. They usually start exhibiting hot no start signs and slowly diminishing power.

To check the fuel cut-off switch, apply 12 volts from the battery directly to the connector and listen for a click. If you get a click, the switch should still be good.

When you say you have power to the GP's, did you actually check the GP's to see if they are lighting up?? Just a few bad GP's with cold temps can make some hard starting.

Let us know what you find and we'll help!

[KidKodiak]

Thanks a lot, Sub, for your help with this post and the other one. I haven't pulled any glow plugs yet to see if they physically light up. I just used a circuit tester, and they did have power getting to them. I have been lucky enough to have temps in the 45 - 60 range last week so I don't think this would be cold enough to need all 8 glow plugs to start.

Fuel is being pumped out of the fuel filter/water separator, but none is coming out of the injector pump. I removed the return hose from the end closer to the fan, and no fuel is coming out. The engine always cranks, but just won't fire.

Unfortunately this suburban is part of a deceased family member's estate. I have no information about any of its repair history. So I'm just starting double blind - new to the 6.2 and no owner to help with the diagnosis. Neighbors have told me that it has been sitting for 2 years without being driven. It may have been started, though. I doubt this since the 2 batteries I pulled from it are completely shot.

It is completely blocked by a 30ft. camper trailer, another vehicle, a landscaping wall, and a wall of a garage.

Would a malfunctioning HPAC, itself, cause the pump not to run?

Thanks again, for your help.

[Robyn]

If you are getting power to the IP, then it should CLICK when the key is turned to ON

Try having a helper trun the key to on while you listen at the IP

If no click then the solenoid in the IP is BAD.

If it clicks the thing should run. If you changed the filters, then cranked the engine you may have gotten air into the system.

Keep us posted

Robyn

[Yukon6.2]

Hi
Pull the glow plugs to verify they are working.I had a set go bad,only one was working.I had the trucks block heater pluged in and the motor was warm,and it would not start without glow plugs.I pulled the plugs and they were wet with diesel.Put in a used set that was good and the motor fired up like it had been running all day.You will need at least 1/2 of them to work to get it to run.Try pluging in the block heater if you can,and get some good glowplugs,the set that went bad on me were boxed in Delphi box's/Welman makes a good plug that is quick to heat up and wouln't swell up when they go bad.
Good luck
Thomas

[KidKodiak]

Thank you both. Very helpful info. I have never removed a glow plug. Is there anything I should know before I attempt it? The manager of the local Carquest used to work on the CUCVs while he was in the National Guard. He stated that the glow plugs will probably break inside because they swell.

What do I do if they do break inside the cylinder?

Would it be a good idea, or a bad idea to spray the threads with Break-away?

Are there any specialty tools I should have before I begin? Or will a standard deep-well socket be just fine?


I bought the Haynes Techbook Diesel repair manual. It is pretty good, although somewhat limited. I also bought the two books from DP, and a GM owner's manual from a salvage yard in Iowa- still waiting for it to arrive next week.

Are there any other reference books that any of you use for wiring diagrams, part numbers, photos, etc?

Photos help me greatly since I'm limited in my diesel experience. LOL I've also noticed that Rockauto.com and NAPA have different photos for the same part name. So this makes my brain work a little harder to determine which one is correct.

I will be a very happy camper if I can get this beastly beauty running.

[Robyn]

Glow plug breakage sucks, but is not the normal way things go.

If the truck has been in SALT country, anything is possible.

Normally a simple 1/4 drive deep socket and wratchet will get them right out.

They seat against a taper so they can take a little pressure.

Always use neverseaze on the threads and the seat when you install them.

Missy

[JohnC]

No need to remove them at this point. Get a test light or an Ohm meter. connect the test light to the battery + and touch the probe to the connector on each of the accessible glow plugs (after removing the wire). If the lamp lights the glow plug is almost certainly good. With the Ohm meter, test for resistance from the connector to ground. Expect about 1 Ohm for a good plug.

[KidKodiak]

Ok. Good to know. I'll do that and let ya know what I find out.
Thanks again.

[KidKodiak]

Well, I've been trying to buy this from a family member's estate. However certain controlling parties of the estate aren't cooperating. So I decided not to put anymore time and energy into it until the title has my name on it. I will certainly post any updates as soon as I can fire it up.

[BigGun J]

When you have an opportunity to go back and it is yours I would have a new set of glow plugs. Pull them all. With the plugs out, the motor will turn over very easily. Watch for fuel mist to come out of the holes. Now you have confirmned that you have fuel flowing from the IP and that dilemma problem is over. Small amount of anti-seize as Robyn mentioned on the glows and install. Now when you turn the key to the on position you should have about a 10 second wait to start light. If no wait, or very quick then you may have a bad glow relay. Hopefully you will have the proper wait time and she will fire right up. I would add some power service to the tank, fill her up and give it good drive. Change the oil and filter with Rotelo 15-40W dino and enjoy.

Also, not a bad idea to make sure a critter has not made a home in the air cleaner, air intake duct.

Jim

[KidKodiak]

Excellent advice, Jim. Thanks. I did put in a new glow plug relay/controller, it actually solved the exact problem you described. The very first thing I did was the oil change just in case there was water in the pan. It seems that Rotella T is the oil of choice.

Between this suburban and the CUCV, I'm in for a fun lesson in diesel mechanics. ha ha.