Okay actually it should read trash in the sock.

I'm in Houston working at a trade show, I drove over from Ms, Sunday nite, and get near to Beaumont, Tx and one of my vac filter blocked switches starts indicating blocked filter on the frame rail pre IP filter, my IP inlet pressure gauge hovering 0-1 psi from it's normal 5 psi. As luck would have it I didn't have a spare filter with me nor none at the 1 autopart store I could find open on a Sunday nite. Being that I have a Racor mount, it has 2 extra ports I'm not using for inlet/outlet, and I was able to come up with fittings/hose to fashion a bypass around the filter element.

The bypass helped some but did not cure the problem; 90 miles out I ring up GMCTD to see if he is going to be up for a while just in case it dies completely & I mite need roadside assist, Diesel gods smiled on me balance of evening, and I was able to limp into Houston 60 mph max before staring fishbiting.

Monday I limp it over to GMCTD's by time I get there both the prefilter hi vac and the on engine filter hi vac alarm are coming on and truck is fishbiting above 40 mph now.

We hit some part stores, grab some new filters, a new lift pump (just in case), lift pump at idle weak flow from on engine manager drain 3-4 psi running sounds are weak. We pulled the on engine filter it was clean, so next obvious possibility is to pull the Racor prefilter, older style elements are not visible without cutting the filter apart, newer style I had just purchased WIX (not actual Racor) have been redesigned so the inlet side flow is visible when removed off of the head.

The bypass I had installed Sunday was removed and the new element installed, reprimed/started the pump with run jumper, (pics will be added when I get home with access to the camera) lift pressure was back up to 5 psi. Priming with the manual prime pump on top of the Racor was difficult (missed clue we came to find out later) so we forced the lift pump to run cheating. I went for a test spin and had to come back still had lites and low lift pump pressure.

Being pressed for time, I opted to replace the lift pump with the new one and also used LP air to blow back through the in tank sock. Life was good I hate troubleshooting by doing 2 things at once, but sometimes one has gotta do what one has gotta do. Anyway I drove around Houston area a couple of days then I started getting the filter light again, low lift pressure 0-4 psi dependings how hard I was running the engine. Yo GMCTD what you doing this afternoon, up for some more work, come on over.

Yesterday the truck up & quit as I was rolling out of hotel parking enroute to GMCTDs it went completely dead on roadside, I crawled under truck, disconnected the Racor inlet line, blew back thru the sock with emergency air source (me :eek: :eek: :eek: ) as luck would have it my tire inflator was in the Burb; It didn't take much effort to clear the sock, I reconnected it started the truck & after a couple of stall episodes before I was able to get it it settled out and I was able to limp to GMCTD's by time I got there I was back to 40mph max speed and both filter vac switches lit up.

When I got to GMCTD's, we pumped out the tank, the fuel removed was clean, dropped the tank and removed the sender unit, the pickup was nearly plugged solid with various types of crud and a sticky tar type residue which I assume to be dead algea & rust congealed together. We cleaned the pickup sock, then mopped out the tank using a cotton foot sock on end of a piece of heavy gauge wire, wringing out fuel and sediment. The tank was mostly clean but sufficient residue in the flow dam baffle & sock pickup area to to crud up the pickup.

Reassembled the tank, plumbing, sender etc. put the fuel back in zippity-doo-dah we had a :grd: moment, all was good on the return trip to my hotel, no filter DP alarms and fuel pressure was never below 4 psi, to about 75 mph, I'll run it out more on my return to Ms this afternoon.

Couple of observations during the troubleshooting, #1 the tech manual for OBD-II is correct the OPS is a backup power supply for the lift pump, the lift pump remains powered with PCM contol or OPS, as verified by removing lift pump relay or unplugging the OPS, remove one or other and pump stays running, remove both and lift pump stops, also with a healthy IP it will pull it's own fuel without aid of lift.

I have doubts however of it pulling it's own fuel through a plugged fuel filter, or in tank sock if weak, combine partial blockage of both you ain't going anywhere fast if at all, so prime suspect to be considered in any fishbite situation is in tank sock, not easiest to check, so do the easy stuff first.

2nd observation is as we have said time & again check the grounds, when dropping the tank there is 1 very important gnd lug (again pics when I get home) on top of the frame rail adjacent to the tank sender weatherpack connector, it is the gnd for the lift pump. We were doing some preliminary testing before securing the tank 100% and could not get the lift pump to run, hmnn what is up with that, light bulb I wonder if that removed gnd lug goes to lift pump, reconnected it yup that is what it wuz. So another fishbite candidate to consider is the gnd lug at that point.

I'll be doing full pictorial later as the sender on the Burb is bad and I'll be dropping that tank as well in near future.

Bottom line keep like your mother said change your socks often & keep em clean or you will get a fungus.

With that thought you often hear us recommending to buy from known good fuel sources, you can try even though doing that stuff still happens.

I'm thinking that possibly as a preventative measure one may want to periodically drop the tank to check the sock, since I'm a 98 one could theorize check it at about 8-9 years would be a good periodicity for checking.

More later

Hi Tim,

Great post, and will look forward to the pictures. Good debugging by you and GMCTD.

Sincerely,

Rob :)

I just hate dirty socks.

Sounds like it was "real" fun. The dirty sock would be something to easily over look or not even consider as an issue.

Good advice to check the tank occassionally. :)

Two of the best heads got it done!!!. How long & many parts DOLLARS would it have taken a MR Goodwrench ??? Your warning systems paid off in spades!!! You guys are so good you should post all the ways to contact you when this happens to us underlings,Ha, Ha & a big LOL!!!

these socks serve a purpose, but they're a bad design in that they are not easily accessible for replacement.

What would be the down side to deleting the sock and just using a universal fuel filter before the LP?

Such a colorful thread title. :rolleyes:

Great timing too. Just sprang a fuel tank leak on the Tahoe. Was planning to just drain the tank and patch it in place. After reading this I guess I will drop it and check out the condition of my sock.

I've got a few more years on mine than TD does on his, wonder if the different climates we live in will impact how much crud we find?

these socks serve a purpose, but they're a bad design in that they are not easily accessible for replacement.

What would be the down side to deleting the sock and just using a universal fuel filter before the LP?

My thought exactly. Is there something in the pickup tube-to-fuel line region that has to be kept clean? I'd much rather deal w/ a filter near the LP.

Chaser

That was a good read, and I'm glad you have it all figured out. I was on the edge of my seat at one point; frankly, I could never have been so organized and completed the fix in such an experienced way.

As a diesel newbie I'm now a little scared to take my rig on long trips :(. I'll either have to (a) get over it, or (b) get greasy and become less of a novice! (prolly both!)

Jon

As a diesel newbie I'm now a little scared to take my rig on long trips :(. I'll either have to (a) get over it, or (b) get greasy and become less of a novice! (prolly both!)

Jon

.... or have some friends along the way....

Shame it didn't happen while around home, but what better place to have it happen, eh what? You and JD doin' a bench press on a fuel tank on an unplanned trip, but hope you still get some time to do some of the testin' wanted to do together.

Good write up- one to remember when problems arise.

I am fortunate to be able to buy our fuel from a local jobber that sells mostly to big trucks. He moves a lot of fuel through his yard and never a complaint in 12 years.

As far as socks go, I think the old Mercedes had the best set up. IIRC, the fuel line came out the bottom of the tank in the middle of a larger nut ( 27MM I think) that contained the sock. To replace it, you just had to drain tank, unscrew fuel line, then the nut with the sock.

BTW DOc, If you think you got some bad fuel along the way from MS on I-10, lwt me know. I travel that way some times and worry about some of those old in ground tanks,

these socks serve a purpose, but they're a bad design in that they are not easily accessible for replacement.

What would be the down side to deleting the sock and just using a universal fuel filter before the LP?

The sock helps keep water in the tank and out of the fuel system. A water separator can help but the sock keeps the water in fuel at a very low level so as not to overpower the water separator

Nice write up TD. We can add that one to our list of things to check when all else is failing. The pics will be appreciated.

You guys are the best of the best! :hail:

I thoroughly enjoyed reading the story (well told).

Sounds like all that jet-wrenchin' has paid off. I haven't seen the inside of your truck, but I have it pictured looking like the cockpit of a 737 with all the warning lights and gauges!! Kudos on your early warning system you built, -sounds like it was well worth the effort.

I'm glad you were able to get 'er up and runnin'. It couldn't have happened in a more conveniant place havin' JD there to help.

Nice work guys.

Rich.

The sock helps keep water in the tank and out of the fuel system. A water separator can help but the sock keeps the water in fuel at a very low level so as not to overpower the water separator

How much water are we talking about?

Good read guys.

Here are some thoughts... I have seen the sock fill up on with rusty crud slime stuff too on 2 gas vehicles. 1 was about 10 yrs old other was 20 ish. Both had different lives and periods of daily driving and and some significant extended resting. Most daily drivers last a lifetime. Also depends on regular fuel source too I imagine.

Yeah initial thought is to take out the sock and run a pre pump filter. But I have had a steel fuel line plug up with the same rusty crud slime on a farm tractor that basically drained out the bottom of the tank. Setup was fuel gravity fed filter and not sure internal to tank. But basically a clot was formed somewhere in line & build up finally plugged the steel line (and could have been some rust from the steel line too). I blew compressed air back through and replace fuel filter and tractor has run fine for 3 years.

I really like the idea of a fairly accessible bottom sock filter like the comment on BMW or Mercedes.

Good fuel/filter practices (which I know Doc does) and the Quality (#1) of the tank are probably the 2 biggest factors to determine life of socks. Seems GM OE tanks are not so good???? This kind of stuff is build up issues mostly and probably not a one time fill up with bad fuel IMO.

Actually - the sock is to reduce reduce entry of air bubbles into the fuel stream - hot Diesel fuel foams easily - when fuel level is low and sloshing around, result is lots of foam, not even welcome at the input to the Inj Pump

You don't want water to take up residence in the fuel tank - Diesel-eating bacteria forms at the Diesel-water interface - it has to travel with the fuel in order for the water separator to function - which is why you don't want to use a water emulsifier - if the droplets are too fine, they pass thru and into the IP - very rustfully damaging in vehicles which are parked for long periods

There is a coarse screened area - ~1/2"dia - on the bottom of the sock intended to pass the heavier stuff off the bottom of the tank and into the fuel manager, with it's centrifugal water\heavy sediment separator - that coarse area was totally plugged with nose excrement - the ~70 micron remainder of the sock was also plugged, as was the filter-bypass valve, intended to supply fuel at incidence of plugged sock

TD's beast could not even be fed due to that sinus-infected sock - the sock and tank is now as clean as we could manage in the short time allowed - prolly will get a new GM sock in the near future

Is there are a way seperate fuel and air if foaming is a problem external to the tank? I've seen some fuel oil supply systems that have air bleeds at the top of a cylinder to vent air. Could a non-clogging version be thunked up?

If the substance was brownish black, and sticky as heck, it is probably sugar. The sugar itself does little to the fuel system, but if it mixes with water, you get the black crud. Had it happen to me on the big truck once. $1000 to clean and rebuild the injector pump.

Jon, who have you been a butthead to?

Any scheme would involve pre-filtration - fill a pre-tank, transfer the fuel to the main tank thru a Racor\equiv - or maybe use an old cotton sock over the end of the nozzle each fillup - would that filter 40gals? - and what would you do with it when done? - pitch it in the trash-can at the island? - certainly wouldn't want it in a baggie under your seat - or in the glove box

I think the Fass (sp?) and the huge volume diesel lift pumps made for racing/ Hi Performance, and Hi HP engines are designed to remove air. Overkill for the 6.5 IMO. There are a couple of flow conditioner gimicky things (for cars and light duty I think they are mostly gimicky) that you put inline that some look like a laminar flow forcers. Kind of like some air intakes units to remove turbulence for flow sensors (a longish honecomb structure). In fuel I think it helps break up any air bubbles (I think is the intent). I want to say Hi performance offshore racing boats its a much bigger issue and they are not gimicky devices for that application. You want good clean dense fuel entering the IP.

Like gmctd posted I think the sock also helps keep air from causing LP cavitation and air from getting to IP. Also is rough prefilter to keep the LP from being a trash pump (at least really big stuff). I think something needs to be at the pickup in tank to keep a clot from forming in the fuel line.

Interesting thread,. Big trucks leave the fuel pickup pipe slightly off the bottom of the tank,. supposedly to let water and crud saty there and not get sucked up into the filters,. BUT,. over the years i,ve had better luck plumbing the fuel pickup intp the bottom of the tanks, it keeps the tanks clean,all the crud and condensation is slurped up and into the filters where it belongs, regular filter changes keep everything good,.
Another good practise is to keep your fuel tank fuel, it keeps condensation to a minimum, if you have a pickup from the bottom of a tank,. you neededn't worry about foaming fuel,. as the foam sits ontop ,.(imagine a beer glass as a fuel tank, foam would be the last thing down the pipe,)
A decent spin on fuel filter mounted on the frame between the tank and the LP,(a nice large raycor heated fuel filter water seperator with a nice see thru base, with sediment drain) and another (full flow spin on) mounted higher than the IP under the hood would give you the best flowing foam free fuel supply,.and natural physics would keep a ready supply of fuel at the pump for starting,.
JMHO
YRRMV
NWEOI
PDCC
Nick

Jon, who have you been a butthead to?

What would make you think I was a butthead? Truck had sat unattended for a few weeks. I have no idea who sugared it.


One of my machines has a removable screen in the filler neck to help keep crap out of the tank. It helps with the foaming too. I wonder if you couldn't rig something similar in the filler neck on the truck too.

TD and I both have that very Racor filter assembly installed between the tank and the lift pump - mine is 2m, his is 10m

But, as indicated, his filter element was clean, only a little sludge in the bowl - it was the in-tank sock that was totally plugged, no hope of any more sludge getting thru to the Racor.

Would be nice to have a big-rig type tank, with the bottom-tap for draining the sludge - automotive tanks had that feature, back when I was young, sometime last century - would also be nice to have the easy accessibility of those saddle tanks

You guys keep posting ideas and suggestions - keep it coming - maybe we can come up with something workable - ULSD is rumored to break up stuff in the system and get it circulating, so we'll prolly be seeing more of this type symptom

Me, I gots lots of old cotton socks needing re-deployment

Have an old diesel farm tractor that I had to remove the sock(clogged)from many years ago.To compensate,I fuel it using a funnel with a fine screen (will separate water).What has surprised me is the lack of contamination showing up on sceen from incoming fuel-virtually nothing.

Diesel-T I don't think its from a one or 10 time fill up. Its build up over many years and tank deterioration. Cavitation was the wrong term earlier but I think its descriptive to sucking air too.

Link to related thread
http://dieselplace.com/forum/showthread.php?t=180901

Okay finished dropping tank on the Burb this weekend, 1st time I used my new Makita 3/8" dr cordless impact as well, 2.8# with battery good for 78'# torque.

Since I did not have camera with me in Houston and I wasn't going to drop tank again anytime soon on again the K1500 some stuff I did on the Burb that I did have camera for; we will assume to be mostly similar to what I did on truck pics here are the truck pics next series will be the Burb pics.

All assumes you have pumped tank dry of fuel, to finish off removing fuel on OBD-II possibly OBD-I you can jumper the lift pump test connector to finish tank empty, I don't recommend to completely drain this way lift pump is only 15 gph

After removing 3 screws from filler neck so it is sort of loose, you can access the neck gnd , the filler & vent clamps, also reach up on top of frame rail just fwd of where the filler neck crosses over the frame rail & unplug the tank sender connector, take note now is a good time to clean that area where the female plug clamps to the top of the frame rail, as the lift pump gnd is there also.

On a K1500 (side saddle single tank) possibly others, unclip fuel suction & return lines from the frame as far as you can this will allow the slack in the hoses so tank can be lowered; also you will want to pull back the suction & return lines from top of tank. So now you should have tank mostly empty, lines unclipped, sender wires unplugged works better with 2 people but 1 can do it either get under tank for support, or use floor jack, remove aft strap that goes around tank & pivot out of way, then remove front bracket/stap at frame studs leave bracket on worked for me. carefully lower tank (it is still connected to the suction & return line), I blocked up under mine with wood blocks as I lowered it.

With tank lowered you can access the 2 lines on top of tank & disconnect 19mm & 16mm wrenches required.

Reverse the procedure to reinstall basically, okay now to the Burb for pics of what I didn't take pics of on the truck

Burb wasn't getting a good tank level so I ordered a new sender, Burb tank is slightly different than the truck, tank is bigger, but mounts also under cargo area between the frame rails. Since I was home I backed the Burb up on my ramps for a little more working room, a bucket took place of wooden blocks used on the K1500 tank. Same procedure more or less as on the truck disconnect plumbing, but tank sender & lift pump gnd are on cross over frame rail above the rear diff. pics 2350 & 2351 show connector & lift pump gnd, do not forget to unplug this before dropping tank, it won't go :eek:

Once tank straps bolts can be removed slowly tilt down tank & support it while accessing the 2 fittings on top of the tank.

When I removed the tank and rotated the lock ring out of the way a couple of things were found, 1st the float arm was not connected to the sender, and 2nd the baffle tray was not attached to the base of the tank, i don't know if it was built that way but it is working correctly now.

More Pics to follow

Burb wasn't getting a good tank level so I ordered a new sender, Burb tank is slightly different than the truck, tank is bigger, but mounts also under cargo area between the frame rails.

More Pics to follow

Burb tank looks like my cab & chassie tank 31 gallon just replaced mine it was leaking in the seam...my old tank was on there for 250,000 miles and it was clean in side no slim or sludge...

Burb tank looks like my cab & chassie tank 31 gallon just replaced mine it was leaking in the seam...my old tank was on there for 250,000 miles and it was clean in side no slim or sludge...

I think mine is a 43 gal I put in 31 gal after pumping in about 10 or so gal from my bulk tank I carry in the back of the K1500, now that I have a working sender I can run it down.

Snoot free. Looks good. Hey thanks for the call this morning T-DOC

One of the discussions I had with TD the other day was the idea (see also from the fuel polishing thread) was the idea of filtration on-board.

This was my first idea. But the factory fuel system kinda "polishes" the fuel as you go. You have return fuel pumping back into the tank after it's been through the filter.

Second idea, how 'bout a mesh screen or sock in the filler neck... well that got shot down too because of fuel foaming.

The stuff in the tank either gets put there by when you fill your tank (depositing sludge in your tank), rust/moisture, etc internal tank deterioration, or biological growth.

How do you avoid biological growth?
1. Have a properly operating fuel cap that doesn't stay "open" to the atomosphere for continuous exchange of air flow between tank and ambient. This increases the chances of moisture being introduced into the tank.

2. Good fuel station purchase. Where-ever there's a lot of diesel getting moved, would be considered one up from the discount retailer that has one pump that all the the little Hondas park at when you need the ONLY diesel pump in the whole station.

Pre-filtering your fuel before it enters your tank would be about the only solution to making sure that you reduce your chances of sludgy build up... as long as you don't forget about the chances of building up any moisture or having a bio-attack on the fuel system.

Pics inside the tank show loose baffle tray, when reinstalling tank do not forget to run float sensor, pigtail forward and over cross frame so it can be plugged back in once tank is seated not much repositioning room.

One last note when handling fuel tank leave it in the plastic rock shield as much as possible, so you don't scratch the protective coating on the outside of the tank

Here is the infamous sock, the one yer momma fergot to tell ya to KEEP IT CLEAN, DAMMIT!!!!!!

Note: the lighter spot towards the right end is the coarse-filter area which faces the bottom of the tank, intended to slurp up all the water and sludge for the water-separator element in the fuel filter manager- the required bypass valve is at the left end - don't put no gasser (patooie!) sock in there!!

http://www.dieselplace.com/forum/showpost.php?p=1628943&postcount=31

edited Teromas pic a little to point out whut it be like, also a pic of a sock cleaned up some

Here at end of thread is how to power a lift pump for test http://dieselplace.com/forum/showthread.php?t=39350

Had it occur again in Nov. found out where snot was coming from, on some visits to our test cell I occasionally dispose of Hazmat waste fuel for them :D , stuff they would pay to have hauled off,

But dummy me :( I was just pulling suction unfiltered from the drum, some of this "waste fuel" while good to burn, comes from the dirty side of the test cell filter bank, which gets some sort of cellulose in it from who knows where, but the cellulose was blocking the 70 micron sock when it accumulated, I've since incorporated a 10micron filter on my transfer pump.

Had it occur again in Nov. found out where snot was coming from, on some visits to our test cell I occasionally dispose of Hazmat waste fuel for them :D , stuff they would pay to have hauled off,


Hmm,. you a licensed hazmat mobile treatment facility??:D
hope you're being well compensated, for the very technologically advanced thermal disposal unit you're operating,.
i haul contaminated soil, mostly contaminated with hydrocarbons (fancy name for most fuels and solvents) seems the customers pay exceptionally wel, and there's a very tight start to finish paperwork trail, hope you don't end up being a victim of an enviromental audit,.
nick

The paper trail for Hazmat only tracks it for transport. A local testing firm used to supply me with all the heavy lube, hydraulic oil, and grease I could use. But I had to pick it up at the facility and actually "use" it. Which I did.

Ah, those were the days.

All the neighbors never could figure out why they never needed to mow the lawn, but they were happy about it...:rolleyes: ;) :)

Hmm,. you a licensed hazmat mobile treatment facility??:D
hope you're being well compensated, for the very technologically advanced thermal disposal unit you're operating,.
i haul contaminated soil, mostly contaminated with hydrocarbons (fancy name for most fuels and solvents) seems the customers pay exceptionally wel, and there's a very tight start to finish paperwork trail, hope you don't end up being a victim of an enviromental audit,.
nick

Well I get paid mileage to use my personal vehicle to drive the 475 miles each way from home & back to the test cell, and the hazmat fluid doesn't get documented until a hazmat company gets called to make a pickup, so if I get to it before the hazmat truck gets called, they never get the call, ergo no paperwork.

How 'bout one of those transfer tanks with the toolbox look right behind the cab? Filter it as it goes into that and then pump from there through a 2 micron filter into truck tank? Add some bio-additive of some sort to make sure you don't get any growth. Still get the benefit of "hazmat fuel" just filtered better. Kinda what the WVO go through, except you just need some filtration.