Use of Diesel 911, fuel gummed up and engine knock w/o power

During the winter, temps got down below freezing overnight for several weeks. Concerned about fuel gelling, I bought Diesel 911 and added it to my M936A1 fuel tanks. Every couple of weeks afterward, I would fire the engine and noticed that the initial start would "spike" and the engine would quit. Thereafter it would restart and run normal. I added additional fresh fuel to the tank afterwards.

Recently, after 6-8 weeks of just being too busy, I fired the truck up and experienced a loud knocking and extremely rough running motor w/o much power. The knock almost sounded like a bad rod bearing but there would be no reason for a sudden rod knock, particularly with a sudden rough running motor.

I dropped the fuel filter and it was full of murky crap and an accumulation of rust in the very bottom (my bad). I cleaned it and installed a new Wix filter adding fresh fuel and injector cleaner. I then removed the fuel fill basket and noticed a dark brown shellac substance on the bottom of the tank. I drained the tank and was able to clean the shellac off the left side of the driver side tank. The tank is baffled so I could not do anything about the right side of the tank. The shellac was sticky and gummy. The Diesel 911 converted the clean fuel into this contamination.

I was able to purge the air from the filter and PT and get the truck started again.. The knock is not nearly as bad but the motor still is w/o power and rough running. It would smooth out around 1200 rpm. I let it run for about 20 minutes hoping for the crap to burn out of the fuel system/injectors. I then used a infra-red heat gun and checked each exhaust outlet. The temp ranged from 155-180 except the center head read 275. I shut it down afterwards. My M923A1 with a NOS motor showed consistent temp readings of 153-155on all exhaust ports. So my best guess at this juncture is #4 cylinder is running lean with a stuck injector, burned valves or? If #4 injector is stuck, most likely all of them will need to be pulled.

I''m looking for advice and suggestions or if anyone has experienced similar issues. I'm really bummed as this truck was an excellent runner before this. Started on the first bump of the ignition. Thanks guys and stay away from Diesel 911.

I use 911 religiously. Tractors, trucks everything. Never had a single problem ever. I think it helped uncover some other issue that has sat dormant previously. If this stuff was so bad there would be ALOT if broke down trucks.

http://www.google.com/cse?cx=partne...&q=911&sa=Search#gsc.tab=0&gsc.q=911 additive

Over 150 search results for "911 additive", and your the first to post that it can cause rust or gum.

never had a problem with 911 when buying a piece of equipment drain all fluids and clean fuel tanks and refill. Also remove hubs on all wheels check the bearings I would do this to any MV before I start it or drive them

911 is a staple for my truck and equipment for many years... I never had a problem if it was a clean system with good fuel...

When I was in the Active Army some of the 900 series trucks had a problem with a coating on the inside of the tanks dissolving and gunking up the system. There was no rhyme or reason for what caused it. You could have five trucks line up and only one or two would have the problem. The official cure was to send the truck to 3rd Shop Maint. and they would replace the tank. This happened at Fort Benning in my case and we never used fuel additives other than pouring a can of automatic transmission fluid in the tank occasionally.
If this is your problem you might take the tank off and have it boiled out (if there is someone in your area that can do it).
Hope this helps.

I had this same problem with my bucket truck (DT466). I like to stay on top of fuel filters. Started noticing loss of power along with what i thought was rust in primary and secondary filters. Buisness was crazy so delayed investigating and just changed filters acordingly. Well finally had a free weekend .. wow what a mess . Long story short cut the end off fuel tank off and cleaned, welded back together. Did so all the way up to injectors as they seemed to have been spared. I got wondernin about the massive amount of what i thought was rust (im talking a couple shoe boxes worth). Well i got out a magnet, guess what wasn't metal. Turns out it was a liner that broke down inside fuel tank. Made a phone call to a friend. He comfirmed and says his shops leaves tanks bare and recomends keeping tank full when possible especially in summer due to condisation. And yes truck runs like a dream now!

I've put 911 several times in my bulk tank when filling and haven't had a problem with farm tractors, F250 or any of my MVs.

Well not sure what to think now. Prior to using the 911, I've used the regular version of Diesel Power fuel treatment since I acquired the truck in 2012. Only the driver tank was gummed up and received the 911 treatment. The larger problem now is the rough running motor, no power and knocking. Any thoughts on the variance in the exhaust manifold temps ranging in the mid 150-170s yet the center head rear exhaust is spiking upwards of 275?

The temp imbalance could be caused from injectors being plugged at the low temp points

My two cents.. Until this truck has the tank cleaned lines flushed and anything between tank and injectors cleaned it's going to continue to have problems. From that point you'll have a clean slate too work from and more than likely be in the clear

What I would like to know is how that crap got past his primary and secondary fuel filters.? Has that crap been building up past his filters and the 911 broke it loose, and got his injector stick or something?

From his description its only being assumed that the injector could be bad based on temp read. I'm inclined to think that there all running very lean. But not because of injector faliur but what's behind them in system.

With all the positive comments re Diesel 911, we're thinking it broke whatever the bad stuff was inside the tank. With the fuel filler baskets on these trucks, you can't peer inside the tank. A heavy duty strap wrench and I've now removed the fuel filler baskets off my trucks. They just corrode anyway. Otherwise I would have known about the gummy dark brown shellac accumulation in the driver tank. The passenger tank was fine other than pieces of broken fuel cap gasket and fine debris. I recommend at minimum the fuel baskets be removed for a physical check of the inside of the fuel tanks.

We are hoping as 1lineman1 said its whats between the injector pump and the injectors and the motor is running lean, more so on the center head. The truck still will start with just the bump of the starter. The hard diesel rattle is pretty unnerving as it shakes heck out of the truck. The pump on the wrecker is totally different than the M923A1 pump because of the auto kick-up feature while running the crane. I still can't find where the PT screen is located on the pump to remove and clean. Also can't find the secondary fuel filter some guys mention. Both my trucks have what appears to be a small inline filter bolted to the driver side of the block with a fuel line screwed into it, is that the secondary filter? If so anyone have a part number? Thanks for all your offered insight and advice.

Some might have assumed you had an 8.3 CTA motor which has a small engine mounted filter or they assumed you might have added one as many do beyond the large canister filter that is originally in the drivers wheel well. I personally suggest if you only have the OEM single large filter to install a second finer (smaller micron rating) filter just prior to the IP as the OEM large filter does not filter as well as what is available to us.

The first duce I got ran bad and I finally changed the filter once I got it home. The filter was so old and full of crap it collapsed and let crud past to the secondaries and had clogged them on one had a hole in it letting crap past. I guess the only saving grace was the last filter that kept the pump and injectors from getting toasted. I hanged everything as well as cleaning the tank which was full of scale and bacteria. Steam cleaner got it done. After that the first thing I do is drain the tank and rinse it out before cranking on a recovery and new filters. You would be surprised whats in the tanks after they have sat for a while and what people put in them. The last on I got had a mixture of jet fuel and water in the tank, a nice creamy color when agitated.

Good call, once I resolve this mess I'm going to install a Racor water sepearation filter just prior to the pump :0(

Well I think I had one or more hung injectors. With Lucas injector cleaner in the cleaned tank and some premium 2 stroke oil, the truck now idles nicely and will rev with a bog down and catch back up. I drove it around the neighborhood and found it simply has no power. I kept it in 2nd gear, 3rd it will simply bog down and not pull. I checked the exhaust manifold ports and they all seemed to run around 180F, #3 cylinder runs slightly higher around 210F. I still can't find the IP filter screen cover on the M936A1 dual circuit IP. Anyone here dealt with their IP screen on a wrecker? Albert?

m923a1, nhc-250, had slime in tank, clened tank. changed fuel filter, now truck won't run, got fuel coming out of the emergency cut off valve, good flow, truck will start and run on starting fluid. for a few seconds. one cylinder fires a little without starting fluid. are my injectors fouled. what can I do ? truck ran perfect before. somebody help me, PLZ.

bradmachine said:

m923a1, nhc-250, had slime in tank, clened tank. changed fuel filter, now truck won't run, got fuel coming out of the emergency cut off valve, good flow, truck will start and run on starting fluid. for a few seconds. one cylinder fires a little without starting fluid. are my injectors fouled. what can I do ? truck ran perfect before. somebody help me, PLZ.

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You’re likely sucking air somewhere. Go back over what you have done. This thread is over 5 years old. May want to start a new one for your issue. Good bit of bad/misleading info in this thread anyway....