Runs for different amounts of time then dies...

[Steve93mustanglx]

Hey folks, been a loooooong while since I posted in here. In a bind with the Suburban again and need a fresh set of eyes and ideas.

95 Suburban, K2500, 6.5TD 4x4. Mods: OPS bypass, Pinnacle exhaust. chipped, mechanical waste gate, vac pump delete, K&N, feed the beast mod, relocated FSD on heat sink in bumper, DMAX fan, big ass alternator and homemade battery cables from 2-0 welders cable.

I had all the above mods for YEARS without issue.

The issue: about a YEAR ago I was going down the highway and she hiccupped on me. Felt like an engine shudder. Next thing you know I am losing major power, gray and black smoke, losing speed, then dead. FFM was empty. Cold hear the pump going to town. It was loud and figured it was not pumping so I replaced pump. Drove, same thing. Bought a better, more expensive AC Delco pump and new fuel filter. Same thing. Dropped tank, spotless. Checked fuel lines. Some a bit knarly with rust but no leaks. Even used an emissions smoker to test fuel lines. No problem. REPLACED ALL rubber hoses at FFM. Still issues. Replaced fuel cap with DIESEL cap. Same issue. Truck sat this past year only to be started every few weeks to run for an hour to keep batteries charged.

Have voltage at pump, am able to prime FFM, can fire it up and do FFM test as well as the t-handle test while running. Engine keeps on trucking during those tests. Today I drove for an HOUR- normal driving and maniac acceleration mode. Then it finally died again. I went to fuel cap- TONS of vacuum, and FFM empty.

WTH??? At wits end and ready to sell! Help!

 

[ak diesel driver]

have you tried leaving the cap loose or off?

 

[Steve93mustanglx]

Yes sir. Issue exists with cap completely off.

 

[ak diesel driver]

i'd look real close at items such as tank sock, steel lines for pin holes sucking air, rubber lines getting soft and collapsing internally, last ditch screen in the FFM, even the return lines can cause issues

 

[Steve93mustanglx]

In tank unit only few years old- removed anyway and checked. No issues. All rubber hoses replaced. Steel lines were smoked with emissions tester. Nothing.

 

[Drago]

My Home brew BioD clouded up when it got cold those couple of nights here, ran fine for a min or two then quit. I'm going to let it warm up longer to see if that helps. My son and I got some bad Dino D a few weeks ago. had some water in it. I believe it was from a pump in New Kent

 

[Burning oil]

If you have an aftermarket FSU I can almost gauranty the tank sock is the problem. From your discription only thing it really can be.
Remove tank sock and install a filter before LP somewhere.
You can also try running it on a temp 5gal can to see what happens.

 

[WarWagon]

X2 on the aftermarket tank socks being "wrong". Look for a kinked hose behind the FFM. The IP will pull enough of a vacuum against a restriction that it can boil diesel and cause the lift pump to 'vapor lock'. I noticed this with a kinked hose that would kink completely shut when the engine got hot. Water in the tank can plug the tank sock sometimes.

The factory tank sock had the round "bypass" in it. The other socks are from a aux tank and the round screen is from a Walbro pump. I suggest you get rid of the tank sock.