prime fuel filter?

[bcdriver]

I just bought a 1994 3500 Cheyenne 2 weeks ago with a 6.5 Turbo Diesel. The truck would start surging while driving so I thought about the fuel filter.
I replaced the filter and now I keep killing the battery as I battle to get fuel back in the lines. After like 10 tries it started for 30 seconds then died again. Any suggestions? Reprime, recharge?

[a5150nut]

First off, WELCOME the TDP!
Is your lift pump working?
Did you bleed all the air out of the filter?
Did the top of the filter seal properly?
Do you get fuel out the drain line while engine running if you open the drain valve?
Diesels are a closed fuel system. If you get air into the injection lines you will have to crack the lines at the injectors and remove the air there too.

[bcdriver]

I started the whole process by running the engine while opening the water drain valve as per instructions from the stock manuel. After about 15 seconds of idle with no fluid coming out anywhere the engine stopped. So I continued with replacing the old filter which was quite dirty looking. I opened the air valve and turned it over a few times waiting for fluid to come out the top. No such luck so borrowed vehicle to go get jerry of diesel. I primed the filter housing then kept turning over while waiting for some sign that air was out of lines.

At one point when I had solid charge on both batteries she came to life briefly and then stopped again when I closed the air valve. Could be air in injectors at this point? How do I check lift pump and injectors?

Thank you!

[Robyn]

Howdy and welcome to TDP
First off there is no reason to turn the engine to reprime a filter.
On the RH firewall is a black plastic cover thats held on with (4) plastic tall nuts (factory)

This is the junction panel, on the far side of it closest to the fender is a little black fuse holder. You can lift the little tab slightly and pull the fuse and the wiring down. At this point you will have the fuel pump fuse in your hand.
The fuse has a bare spot on the back side (flat spot) that you can touch to the + stud in that same junction block.
This will power the lift pump.

With the new filter in place remove the fuel delivery hose from the top of the IP (larger one on the LH side of the pump)

Have an assistant hold this hose into a can and then you energize the lift pump by touching the fuse to the stud.
The pump will run as long as the conact is maintained.

Run the pump until you have clear air free fuel at the hose.
Now reconnect the hose to the IP. Do the same thing with the drain hose and run it into a can and run the lift pump unitil air free fuel runs steady.

Now the system is air free and full of fuel.
No need to flatten the batteries and melt the starter.
You need to be sure that the lift pump is running when the engine is running too.
You should be able to get fuel flowing from the drain hose with the engine Idling, If not there is an issue with the lift pump, fuse, relay or pump itelf.
NOTE the lift pump should run with the starter engaged, if not there are issues to be dealt with.

The pump makes a light thumping whirring sound when its running and will run a bit after the rig is shut off especially when the engine is cold. (OIL pressure holds longer)

Once these conditions are met the engine will start right up.
Since you have spun it a lot you most likely have a lot of air in the injector lines and IP so it may be necessary to crack loose a few of the injector lines at the injectors to get the air out.

A fuel filter change normally can be done this way with no extra cranking and fuss.

If you have issues with the lift pump not running it can be the fuse, relay or oil pressure switch thats causing it.
OPS is at the rear of the engine behind the glow plug controller on the rear flange of the block. Its about 3 inches long and has a plug going to it with 3 wires.

Nasty little creture to get to but doable
Check it out and let us know.

Robyn

[bcdriver]

Thanks for your info!

I am quite new to this game. Lots to learn, eh?

Well, I found the fuel pump fuse and junction block but could not see where contact could be made to run lift pump. There are like 4 studs and only one is not connected to something. The fuse is all plastic. I touched it here and there with no results... Key have to be on? No assistant at the moment.

I am thinking it might be lift pump problem because I have yet to see fuel come out the top of the air valve on filter. I also think I located injector lines. 4 thin metal lines on each side leading to where spark plugs would be? How to bleed? crack all 8 nuts and run pump? And then on the water bleed valve I can't see where the drain hose goes. Do I have to remove metal plates from chassis to access?

Bah!

[Robyn]

be sure the fuse is in good order.
The large stud in the junction block that has the large black cable #4 or so hooked to it is hot all the time.

The fuse has a little slot on the back side that will allow you to touch it to the edge of the stud.

If the fuse is blown there may be an issue elsewhere.

Be sure the fuse is ok and then go ahead and touch it to that large stud. The pump should start whirring and thumping when you do this. (No need to turn key on)

If the pump does not start then you need to check the pump.
Its on the inside of the frame rail about underneath the drivers seat.

Keep us informed.

Robyn

[93GMCSierra]

What you have described sounds like a faulty lift pump, an possibly taking out your injection pump.
I have a 93 with a mechanical pump my lift pump quit working an that led to the injection pump failing, head an rotor went out of it. but that is the way it would act when I replaced the fuel filter as well, I have a 5 speed so I would pull start it an it would take a bit but would start.

[Turbine Doc]

See post 18 this thread http://www.thedieselpageforums.com/tdpforum/showthread.php?t=29083&page=2 for easy way to jumper power to test a lift pump for OBD-I trucks, and post 11 for OBD-II trucks

[bcdriver]

It did turn out to be a faulty lift pump. She has been running like a champ for the last 2 weeks until yesterday when I was 300k in to 500k trip home. Started surging and losing power again. I poked around and detected what seems to be an obvious fuel leak coming from under fuel tank in rear. Thinking that might lead to some sort of vacuum leak in system? I suspect new tank install might be tricky and or expensive?

[93GMCSierra]

tank install is extremely easy really, dont know about new tank price though, I pulled my tank to clean it good, lots of crap in the sock an giving me bad fuel. 2 straps is all that holds the tank in place then the filler tube an lines and it drops out, might be nice to have an assistant though, and a good hydrolic jack.

[ccatlett1984]

new 25gal tank for my 85 was $130 plus $35 for straps.

[bl78ljb]

In looking for a new fuel tank check out

http://www.lmctruck.com/icatalog/cd/0116.asp

I purchased my last tank from them and it came with zinc chromate primer on it and an original GM parts tag (MUCH cheaper than the local dealer), and much better quality than the local parts store tank I replaced that only lasted two years. They have both the 25 and 34 gallon tanks ($149) for the same price and all the hardware.