1997 GMC 3500 6.5 Diesel Stopped Running Today

[jrsavoie]

I built a harness for mine that hooks to the battery posts and has a lp connection on the other end. I will look for the other jump location. I built 2 of these harnesses for my trucks.

Only the OBD2 1996 and newer trucks have the jumper wire by the under hood fuse box. On the OBD1 vehicles I jumper the inline fuses I install off the dual lift pump relay upgrades I have done on them. 1995's can be jumpered under the dash and 1994 and older can be jumpered off the lift pump fuse on the right / passenger side firewall. All of which is easier than climbing under the vehicle to plug in the extension / test harness.

When condemning a lift pump, I always use the extension harness at some point in time. I also test lift pumps, one more time after I have them out of the vehicle by trying to pump from one container to another.

There is nothing more frustrating than changing the lift pump and finding out you have a hole in the line or crud in your tank, plugging up the sock. Because you didn't do thorough diagnostics.

From what the Original Poster, OP has said, I am thinking along the same lines as Leroy. If it worked before the glow plug controller change, it should run after.

What prompted changing the controller?

I would also test for voltage at the glow plugs.

 

[kurtis103]

Guys,

Thanks for the info on the jumper point under the hood. I was expecting to do this from under neath the truck. I am hoping that I just pulled the OPS wire or something similar and fell that I have enough info to track it down. At this point it will probably have to wait until the weekend (daylight). I will post my findings.

P.S. I do have voltage at the glow plugs (tested already)

 

[tanman_2006]

Only the OBD2 1996 and newer trucks have the jumper wire by the under hood fuse box. On the OBD1 vehicles I jumper the inline fuses I install off the dual lift pump relay upgrades I have done on them. 1995's can be jumpered under the dash and 1994 and older can be jumpered off the lift pump fuse on the right / passenger side firewall. All of which is easier than climbing under the vehicle to plug in the extension / test harness.

When condemning a lift pump, I always use the extension harness at some point in time. I also test lift pumps, one more time after I have them out of the vehicle by trying to pump from one container to another.

There is nothing more frustrating than changing the lift pump and finding out you have a hole in the line or crud in your tank, plugging up the sock. Because you didn't do thorough diagnostics.

From what the Original Poster, OP has said, I am thinking along the same lines as Leroy. If it worked before the glow plug controller change, it should run after.

What prompted changing the controller?

I would also test for voltage at the glow plugs.

Learned my new facts for the day. Thanks for pointing that out.

 

[625fireman]

OBD I can be jumped in the diagnostics plug under the dash too. I don't remember which pins but will look it up. IIRC its ground pin and LP should run.

 

[kurtis103]

Problem solved today. The problem was the wiring at the lift pump, once I put in a temp splice it started right up. Will have to redo the wiring later this year when it warms up.

 

[Burning oil]

Thats coinceidental eh? Glad you got it fixed.

 

[sureshot]

not trying to scare you but your ip should have been able to suck fuel by its self. i only know because i forgot to hook up a wire when i did my lp relay mod and pl was not running at all truck would idle and run fine but could be starved for fuel if you stepped on it. maybe time to sell the truck if you have it running.

 

[tanman_2006]

x2 with it should pull fuel but I would check for fuel leaks between the LP and IP.

If it doesnt pull fuel then thats still not a big deal if it runs ok w/ the LP running.