Stalls but has new relays & filter - 97 Suburban 6.5TD w/ Heath Mods 5 yrs now

[97Suburban]

Hello fellow 6.5TD fans!!!



I need your help!!
Thanks a million in advance for your help!!!



I have a 97 suburban 2500 4x4 with 171k miles, 2nd owner, mint!!
GM Dealer did ALL work up until I bought it from original owner 5 years ago.
GM Dealer install a NEW DS4 fuel pump at 98k miles


Installed in my truck are the following HeathDiesel.com components installed over the past years and some 5 years ago, like the remote mount PMD
1. Remote mount PMD - Dec2005 123k miles $450
2. Hi performance fuel lift pump - Jan2006 123k miles $110
3. Turbo arm - June 2006 - 129k miles - $110
4. ECM / computer - Nov2006 133k miles $450
5. locking NAPA fuel cap - Nov2006 - 133k miles


MILEAGE is currently at 171k miles.




Then since then, Heath had me install the following last June due to a bucking problem: June 2009
1. Fuel pump relay - GM Dealer OEM part $50
2. Starter relay - GM Dealer OEM part $20
3. Oil Pressure switch - not sure if GM or NAPA...
--> These relays & switches fixed the random bucking problem, perfect fix!!!!!
-->> It has been perfect since putting in those relays last June!!



No ISSUES but for preventative maintenance REPLACE injectos
* Jan2009 - Injectors - Penn Diesel of Harrisburg PA - Rebuilt stock injectors & bench tested $415.

* Jan 2010 - Replaced FUEL TANK PICKIP UNIT due to pin holes and rust. RockAuto
* Reinstalled with best quality NAPA goodyear RUBBER fuel lines, from the fuel tank pickup unit all the way up the frame to about 1.5 feet behind the lift pump, then it was new metal lines or still perfect Original metal lines to the lift pump and left the still good original lines in place the rest of the way up to the engine area.
* Also replaced rusted brakes lines with new coated barkes lines from the rear valve all the up the frame to fresh oem lines.
*Jan2010 - New AMSOil AEAF Air Filter (Absolute Efficiency Air Filter) - This baby out performs K&N, Afe and so on, wow, no more cotton gauze oil soaked filters, now AmsOil all the way :-)



THE CURRENT PROBLEM:
Now, it is randomly stalling, from once a few ago to non-stop now, now unusable

1st - it was random and seldom about 2 to 3 weeks ago.
2. Then last week and then this past week more often.
3. The finally dangerous and not really drivable the past 2 days because it stalls every few mins. My wife pulls over and waits a few mins tries a few times to start it and it starts up again, then stalls in maybe 3 or 4 or 5 mins later again, and do all over again.


---> So I drove it today for a few hours today for saturday errands and sure enough, almost could NOT get home.. it seemed to a fuel supply issue, it seems I could pull over, or coast and turn the key on HALF-WAY until the wait to start light went off to get the LIFT pump to pump some fuel from the tank to the system, and do that about 3 to 4 times and it would fire right up and I could then punch it or go for maybe 3 to 5 miles and it would stall again, and keep doing that until I go my errands done and got home.



So it seemed to be a fuel filter issue(I change the fuel filter every six to 12 months, this time it was a year ago, oops, i only drive this casually), so I added 17 gallons of fuel (almost a half tank) and a QUART of oil and 6 ounces of LUKAS fuel conditioner/treatment for diesel &/or gas and then changed the FUEL FILTER and it ran GREAT for 15 mins, and started stalling all over again, crap...


After the fuel filter change and bleeding the air, it started right back up, seemed perfect!

I let it idle in the driveway and it Stalled in the driveway every 5 mins and I did the lift pump half-key once and it fired back up perfectly, so after the 5th stall, it NEVER stalled again, so I thoughtit must have been air in the system from the fuel filter, so I went for a errand and ran PERFECT for 10 miles, then BAM, sucker shutdown again, and then I played the whole game of key and start and go to get home...



Another scenario a week ago: GET This, I filled it up with a HALF tank of fuel and added the LUKAS treatment and NEVER stalled again until I put in another quarter tank of fuel in it. I don’t always use fuel treatment; I rotate between oil and then the AMSOil diesel treatment and Lukas fuel treatments… so a lot of the times it does NOT get any fuel treatment, say 50% of the time to 60% of the time....


NOTE: I can hear the lift pump under the frame turn on quickly when I turn on the key, so I assume it is ok? although, maybe the lift pump finally is getting weak and cannot get whatever level of fuel pressure constant maybe????

HOW do I check this?? does anyone make a lift pump pressure gauge system??


Is PMD going bad? this was new from heath 5 years ago and mounted under the front bumber/skid plate and NEVER got hot by engine temp? are those things a lifetime warranty, especially at $450 bucks, wow... my buddies buy theirs for $150+ or so for the fenderwell mount systems, so they beat me up at spending a fortune for this, ouch



Is the injection pump ok or going bad? It has 171k on the truck, but GM replaced the injection pump at 98k miles with the latest one, I believe it was the DS4...


So, shall I do the following or not throw everything at it???
I want this to be 100% and reliable for the upcoming winter 6 hour tows to go snowmobiling in the 20 degree weather and NOT breakdown in middle of no where!!!
1. NEW Fuel pump relay from Pep Boys auto house $15
2. Starter relay from Pep Boys auto house $10

3. NEW Lift pump the BRANDS and prices Vary like this:
A) Pep Boys - Carter brand $81
B) AutoZone - AirTex? brand $83
C) Advanced Auto parts - Delfi brand $86 special order
D) NAPA - no idea because these stupid stores close everyday at 5pm while all the other auto stores are open until 9pm, thus, they always loose my business, go figure....




Thanks soooo much in advance for your help!!!

97 Suburban Man!!!

[JTodd]

It sounds like a very similar problem to one I had. It turned out to be a leak in one of the fuel lines between the tank and the lift pump. Because it was never under pressure, it would not leak fuel, but when under vacuum it would suck in air. I ended up dropping the tank (not the most fun thing to do in the driveway on a 5* winter night) and cutting the metal lines coming from the tank and splicing in about 3' of rubber hose. I replaced both to be safe. I have not had a problem since.

[97Suburban]

Thank JTodd for the reply, wow, could be, buy dang, I hope not, we just had the tank out and replaced everything this past Jan, new everything, unless the high end goodyear fuel hose and dual clamps are somehow leaking and sucking air...

ok, I just got done some swaps.
I took the old lift pump I had wrapped up for the past 5 years, and yes it had the ends capped and in a zip lock bad and kept clean, I put it on and it worked immediately, but then after I moved the truck and turned the key on, it refused to pump ever again and didn't allow me bleed the air out of the fuel system, what a pain, so I pulled it off and put back on the old pump and right away, it worked and pump plenty of fuel right away and pumps like mad...

So I suspect the pump that is now back on there is fine, although after 5 years I suspect I should still replace it.

Oh by the way, i did find the old fuel pump relay, it was with my old lift pump in the bag... I did replace the fuel pump relay last year with a ACDelco GM dealer relay.

So now, I threw in my old fuel pump relay and I will take her a drive..
If it still stalls, I will swap the A/C relay with the starter relay...

In mean time, does anyone else have any thoughts or diagnostics?

Thanks again in advance!!!

[DaveBr]

You have a remote mount PMD. If you can find a known good PMD you can swap it out to see if this is your problem.

[97Suburban]

OK, as noted, I swapped the lift pump that seems to be working perfectly, based on always running anytime I turn on the switch.

But as noted below I swapped it back out because it never worked again after it first ran, I suppose it locked up from sitting wrapped up for 5 years? Although, I did have the ends capped and in a zip lock bag??? so it did NOT rust or anything??? Does ANYONE have any thoughts on a lift pump locking up?


Then sunday morning I had to run some errands, then I swapped the fuel relay and starter relay BUT still stalling... then it refused to start again after it stalled pulling into my driveway, dead for good... Then after sitting all day, it started up sunday eve, wow, so something cooled down, so I assume the PMD is maybe getting hot and then stopping to work????
Although it is mounted up under the front bumper, but I guess being electronic, it finally wore out???


I will try somehow to fish the original PMD connection that I stopped using 5 years ago when I installed the HeathDiesel.com remote mount PMD...

I tried to find the connector the old oem PMD, but I can NOT find it for anything, where the heck did that thing fall??? I suspect it may have fallen down towards the back of the engine direction and is under the intake???
--> Will I have to remove the intake or remove the A/C pump or both?

Can someone tell me what the easiest method is to get to the original OEM PMD so that I can unbolt it and use it as a backup?


Thanks again for all your help!

[DaveBr]

Take your upper intake manifold off. This will expose your pump and give you enough room to find your plug in. Just undo the clamp between the turbo and the upper intake. Undo the six bolts on the intake and lift it off.

[97Suburban]

Hi DaveBR, yea thanks, I have had it off several times over the past 5 years, and will probably take it off again so that I can attempt to remove the PMD to use as a backup.

thanks

[97Suburban]

Also, HeathDiesel.com is sending me a new free under warranty on the PMD!! Cool, great service, 7 year warranty!!!

[Robyn]

If the PMD is a Stanadyne unit, its supect from the gitgo.

Get yourself a DTECH PMD as these have the best track record.
Good luck

Just to be sure, once you get it going again, hook up a piece of clear plastic tube to the IP return fitting and run the thing to be sure that air is not the culprit.

You can just temporarily install the plastic return line to watch the return flow.

**** Always carry a spare PMD of Known good working order in the glove box******
Having it ready with a resistor installed and mounted to a little cooler is good.

In a pinch you can simply plug it into the harness and lay it on the engine or ?? to get you home.

Missy

[Yukon6.2]

Hi
I had a Dtech pmd that went bad within 3000 miles/7 months.Looking back it was acting strange right from installation. Unfortantly it installed days befor i ended up having to switch motors,and i was chasing a problem that was the PMD,but thinking that it was new i was looking in all the wrong places.
I am getting a new one on warrenty.
But the Dtech is an electronic device,just as likely to crap out as a stanadyne.Don't be fooled by the fact that a new part is 100%.
If i have to buy another new PMD it will probly be a Dtec,they do seem to be less likely to go bad,but they are the new kid on the block so time will tell.
I was told that Dtec is just the marketing name,the PMD is actually built by Flight Systems.
Good Luck

[97Suburban]

Hi Robyn,

Thanks for the reply.
Yes, a Stanadyne PMD just came off last eve,
Yes the new one is a DTECH!!

Couple Questions
1. Educate me, what did you mean by "get a piece of clear plastic tube to the IP return fitting and run the thing to be sure that air is not the culprit."
Do you mean the T-Handle that I use to bleed the air from the system??

2. What did you mean by having a resistor installed ? what resistor ? where do I get one from, how does it hook up?
Thanks in Advance for the help!

Status so far with the New DTECH
* installed it last eve, ran 20 mins away, then it sat for 3 hours, then drove home, and my wife has ran it all day today in the little heat wave here for a septemper, so far so good!!!!

If the PMD is a Stanadyne unit, its supect from the gitgo.

Get yourself a DTECH PMD as these have the best track record.
Good luck

Just to be sure, once you get it going again, hook up a piece of clear plastic tube to the IP return fitting and run the thing to be sure that air is not the culprit.

You can just temporarily install the plastic return line to watch the return flow.

**** Always carry a spare PMD of Known good working order in the glove box******
Having it ready with a resistor installed and mounted to a little cooler is good.

In a pinch you can simply plug it into the harness and lay it on the engine or ?? to get you home.

Missy