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Steelkilt
12-05-2008, 09:23
I recently purchased a 1998 GMC Suburban 2500 with a 6.5 l diesel (160K miles). I'm completely new to diesel and was wondering if anyone would have a good recommendation on a repair manual for this vehicle so I can learn how to maintain it and keep it running. After 4000 miles the service engine light has come on so I'd like to figure out what is going on.

One question I have, and I know this is a noobie question so forgive me, but I'm hoping to learn the procedure for changing the fuel filter. I've done some searches here but I'm still unsure of the exact procedure for this vehicle. The fuel filter seems to be under an aluminum housing? Is there a bleeder to release air before opening it to remove the filter? How to trigger the lift pump for this model/year to refill the fuel level after filter is in prior to starting?

Thanks!

trbankii
12-05-2008, 09:41
The following books from this website are an excellent resource:

6.5L Turbo Diesel Volume I (http://www.thedieselpage.com/65book.htm)

6.5L Turbo Diesel Volume II (http://www.thedieselpage.com/65bookii.htm)

The 6.2L/6.5L Diesel Troubleshooting & Repair Guide (http://www.thedieselpage.com/t&rguide.htm)

The filter is at the back center of the engine, behind the cover you mention. There is a bleed screw on top of it. My truck is mechanical, but someone should be able to chime in on the electrical pump operation.

Hubert
12-07-2008, 07:14
Read in the owners manual about it for basics then Read, Read Read the forum. There are several posts on fuel filters to get all the tips. Its been posted several times. The owners manual doesn't do it quite justice but is barely ok. Its not hard just takes a little practice to feel real comfortable with it and know what to watch out for.

Your year is OBD-II and lift pump comes on key on run for a little while. Do the lift pump check before starting to make sure its functioning before taking old filter out. ie Engine running open water drain to see if lift pump pushes fuel out of water drain and engine doesn't cut off.

The air bleed is right on top of filter made into the top. Loosen it a little too much and its a mess as its just a plastic knob more or less.

Use good shop practices and common sense need a couple of rags and turkey baster and clean out all the dirty fuel before installing new filter. Make sure screen is in there and finish with air purge. Some top tips are to open water bleed and air bleed then blow in air bleed softly to push some Diesel out of the bowl.

Steelkilt
12-07-2008, 07:21
Do the lift pump check before starting to make sure its functioning before taking old filter out. ie Engine running open water drain to see if lift pump pushes fuel out of water drain and engine doesn't cut off.

Excellent advice! I wish I had thought of this yesterday before I pulled the filter and cleaned out the bowl. Cuz the lift pump isn't working. Now it's just a big driveway blocker. with snow on the ground. live and learn i guess. today's project: figuring out if it's the lift pump or the circuit. Question: is it safe to assume that the brown wire, as opposed to the black, leading to the lift pump is the positive.

suburbanK-2500HD
12-10-2008, 14:27
Probably, but safest is to measure with an instrument..

There is a relay for the lift pump, located under dash, or at the engine wall.
The oil pressure sender also needs oil pressure to start the lift pump..
So when cranking, crank untill you get oil pressure at the gauge..
if it doesnt start pumping(you will hear it, ticking sound)
Then it could be the OPS or pump or relay....
Try to connect power directly to the pump to test.

good luck