6.5 sporatic rough running, like running out of fuel

[captaincrunch]

Hello, everone . . . it's been a while since I've been on here (thank the Lord!)

My ol' 6.5 has been doing wonderful . . .until today. I'm suspecting a PMD, but thought I'd get some opinions . . .

Been cranking and running great. Drove a couple places today and about mid-day, going down the expressway at 70mph it started kicking and sputtering, running rough. I exited and started back home but it stopped.

I pulled into Home Depot to get some things, and afterwards it cranked and ran fine. Still headed home, and once again it started acting up. Then just as I was pulling into my driveway it shut off.

It only took a few seconds to crank it then. Almost acted like it ran out of fuel. But, I changed the fuel filter less than 10,000 miles ago and haven't had any issues until now.

My PMD is mounted on a fin type heat sink on the left fender well under the hood. I know this isnt' the best place. Last installed a PMD in 2007. (wow, didn't realize it had bee that long!)

Looking more like a PMD . . . wouldn't you think?

[arveetek]

A few of us lately have had issues with the fuel sock in the tank getting clogged, restricting flow.

I fought a similar issue for months. Engine would start normally after sitting for a while, but driving down the road would cause it to sputter and stall. Letting it sit (such as waiting for a tow truck) would allow it start and run normally again after purging air out of the system.

After ruling out the PMD, fuel filter housing, rubber fuel lines, and (several) fuel pumps, I finally dropped the tank (again) to only realize that the fuel sock was sucking closed when pumping fuel to the engine. After the engine shut down, the sock would relax and allow fuel to flow again (for a while).

My problem was actually an inferior aftermarket sock. Replacing the sock with the OEM version fixed my issue.

Casey

[captaincrunch]

I did replace the fuel sending unit a couple months ago, cause the guage was going haywire.

I didn't even think about looking at the sock.

Dropping that tank is so much less than fun! In a way, I hope it IS the PMD.

[sctrailrider]

Might try blowing air through the fuel line and see if it blows the sock clear for a while, that might help to see if it is the sock..

[captaincrunch]

If it was the sock being clogged, would it come and go while driving?

It started acting up on the expressway. After I exited it began to run fine, that's why I decided to go ahead and pull into the Home Depot.

I know I've read where sometimes the PMD, when it goes out, the engine just quits abruptly. Each time mine has gone out, it's always been the kicking/sputtering symptoms then eventually it quits and won't re-crank.

Gotta search to see what's the newest, best PMD to purchase. I'm sure a lot has changed in 5 years.

Suggestions are welcome . . .

[arveetek]

If it was the sock being clogged, would it come and go while driving?


Yes it could. It took me months to finally figure out my problem. It seemed so sporadic at first, but finally got worse and worse to the point where I could only drive about 10 miles before she would sputter and shut down.

I had replaced my sending unit with an aftermarket version about 15,000 miles before the symptoms appeared. I believe the aftermarket sock was inferior, and after reinstalling the OEM sock back onto the newer sending unit, my symptoms went away.

I have a D-tech PMD, and have been very satisfied with it.

Casey

[sctrailrider]

It could and does, at road speed or high RMP's the pump is requiring more fuel, and more flow, the sock won't let enough go to the pump.

This will be the cheapest and fastest check and would lead you to the next thing from there if the symptoms don't change..

And did you try removing the tank cap to see if it still does it, have seen caps not vent and cause too much suction for the pump and starve it for fuel...

[captaincrunch]

Yes, you're right . . . it would be cheaper to get a new sock, but it is a pain in the axx to do! If I calculate in my time it probably is just as expensive as changing the PMD.

Are there any sites that give directions on dropping the tank? I may be doing it the hard way.

I was wrong about the date of my PMD, it was bought 5/20/10, only 2 years. But, I'm tempted to just get a new one and see if that does it. I don't know how long they're supposed to last. I bought it from Diesel Care and Performance for $175. I don't know the brand, their website only says "new and improved". I'll have to get out there today and take it off to see if there's a name on it.

Is there a way to test either the PMD or the sock so I can know for sure? I just don't want to drop the tank only to find out it's the PMD.

Inputs, comments, criticisms, or suggestions accepted earnestly . . . . .

[sctrailrider]

Yes, you're right . . . it would be cheaper to get a new sock, but it is a pain in the axx to do! If I calculate in my time it probably is just as expensive as changing the PMD.

Are there any sites that give directions on dropping the tank? I may be doing it the hard way.

I was wrong about the date of my PMD, it was bought 5/20/10, only 2 years. But, I'm tempted to just get a new one and see if that does it. I don't know how long they're supposed to last. I bought it from Diesel Care and Performance for $175. I don't know the brand, their website only says "new and improved". I'll have to get out there today and take it off to see if there's a name on it.

Is there a way to test either the PMD or the sock so I can know for sure? I just don't want to drop the tank only to find out it's the PMD.

Inputs, comments, criticisms, or suggestions accepted earnestly . . . . .

Quickest way to check the sock.... remove the fuel feed line at the LP and blow air through the line, if the sock is clogged it will clear it for a while then clog again, that will let you know it's the sock..

[a5150nut]

Quickest way to check the sock.... remove the fuel feed line at the LP and blow air through the line, if the sock is clogged it will clear it for a while then clog again, that will let you know it's the sock..

And don't forget to remove the fuel cap or you will get quite the suprize!:D

[captaincrunch]

Apparently it was the sock. I had purchased the (http://www.oreillyauto.com/site/c/search/Fuel+Sending+Unit!s!Switch/01997/C0025.oap?model=K1500+Pickup+4WD&vi=1158252&year=1996&make=GMC) Spectra Premium for $76.99 and it uses a sock type filter. I replaced it with the Dorman OE Solutions one for $112.99 and it has a plastic filter.

So far, that seems to have fixed the problem. I did however, have to replace the fuel pump as well. Don't know if it was just old or whether trying to suck fuel through the sock may have damaged it. All I know is it was leaking somewhere.

Thanks for all your help. It was a pain to fix.