Glacier Diesel Power - feed pump users only

[Joe Mc]

Have the GDP-392 w/2 mic filter. It's been fine for a few years 20+ # regardless of throttle position, or comp setting. Recently I noticed the psi would wander down around 16 or so, just cruising, and then ping back to 20. Then I'd see it go down as far as 8, cruising So, I changed the filters, yes plural, I have a pre-pump small Fram that helps screen out yuk to protect the pump. I took the regulator apart and cleaned it as well. A few days go by and all is well. I've noticed on the way to work the psi will bobble down a bit as I get closer to work (about a 45 min ride, speeds ranging from 65 to 25 - stop and go a bit too). One day last week as I was approaching work I noticed the psi at 4 then 0 and then less than 0:{ I come out to go home and all is well till I get close to home same thing. So, I take the pump out and spritz the the inlet and outlet to see if any yuk got in there, nothing. Then I get some clean fuel, attach clear hose to the inlet and outlet connect up to a 12v source and give it a blast - no yuk inside, nice clear fuel? Put it all back together and all is OK. Went for a decent ride this weekend to make sure I'd be OK for the haul to Gettysburg, PA this coming weekend (MDC-Spring Fling) and after about 40 minutes or so same thing? Strange thing whenever I shut down and start up again the psi is fine . . . for a while? So as I'm going down the road and the psi drops, I jog the key to the start position (just like if you jog the key to run the pump for 45 or so seconds to push air out after a filter change) and the psi comes back up - for a while then it starts to dip down again? So I figure maybe the blades on the relay that came with the kit were dirty, took it out cleaned up, dielectric grease and reinstalled. No help, same scenario on the way to and from work today.



So, any ideas on what the heck is going on: sending unit, pump getting hot (doubtful), relay that came with the kit crapping out, is there a stock relay for the original LP that's still in the circuit that's on the way out, or is the regulator hanging open? I'm hoping it's something that can be taken care of before I leave to spin the dyno wheel this Friday.



Appreciate any helpful replies.



Thanks in advance.

 

[PRout]

Is the pickup tube in the tank stock? If so maybe it is sucking contaminants into the screen and plugging it up. . Like maybe disintegrating fuel float level material?? Just my first . 01 thought. .

 

[Joe Mc]

PRout - Good thought. I put a Vulcan draw straw in prior to the GDP pump/system. A thought I just had while reading your reply - the fuel cap may not be venting and/or the tank vent may be clogged. Will have to check those as possibilities.



Keep them ideas a comin`



Thanks,

 

[Blu-meanie]

Did you consider the gauge? Sending unit, connections, etc.

 

[ENafziger]

My gauge started doing the same thing, so I ordered an extra walbro to install. It turns out that the fuel isolator before the gauge failed, and was causing the erratic readings, before failing completely.

If you can, get another gauge, and hook it up under the hood or somewhere to verify pressure.

For what it's worth, I think Power Service and/or Marvel Mystery Oil I was using ate the diaphragm out of the fuel isolator.

--Eric

 

[Joe Mc]

For what it's worth, I think Power Service and/or Marvel Mystery Oil I was using ate the diaphragm out of the fuel isolator. --Eric

Hmmmm? Now there's a possibility?



Spoke w/Rich @ GDP before I left work. Possibly the ECM signal to run the pump, he said if it persists I can remove kit relay and jump the red wires to make run constant. Won't hurt pump as it's designed for constant run. And, it'll get me thru the trip this coming weekendOo. Also mentioned I should check connections from kit relay to harness as he's seen them corrode sometimes.



However, all the way home today it was fine. Lately the weather has been pretty wet and today it was sunny and warm . . . hmmmmm? Have to check them connections to see what's growing. Will keep updating as I go.

 

[Joe Mc]

As embarrassing as it is, I think I found the problem. Solder-less eye connector on battery negative for pump relay was thin and almost broken, a few wiggles and I was holding a wire in my hand. Replaced with a heavier eye connector, I'll see what tomorrow's ride to work yields.

 

[Jeff Knight]

Joe Mc,



I just went through the same thing. My truck lost fuel pressure on the way to cabin for hunting. Had to limp the truck home. It was missing so bad I didn't think I would make it. I talked to Richard at GDP and he sent me a new pump. I Cleaned my prefilter which was dirty. Put everything back together and everything was fine. I got the new pump on Fri and took it with me on a road trip to Western PA. On the way there it started to acted up again. At a friends shop I took the filter apart again and it was clean. I headed home from Mt Pleasant and got to Somerset when it started again. I ended up changing the pump along the PA turnpike in the rain. It's been running fine ever since. Good luck with you problem. Let us know what you find.



Jeff

 

[Joe Mc]

Well it must have been the loose ground because it made it through the week fine and all the way to Gettysburg (in-the rain) through the dyno runs and all the way home (in the rain).



So, knock on wood, all is well.