A ya why dont you get it some less than year and a half old fuel! That would be a great place to start. Actually take the tank out and clean out the fuel system completely, then run it on some fresh fuel and see where your at.
LBZ fuel knock, multiple misfires?
- Thread starter DIGGLER
- Start date
A ya why dont you get it some less than year and a half old fuel! That would be a great place to start. Actually take the tank out and clean out the fuel system completely, then run it on some fresh fuel and see where your at.
It would be best when your posting for help to add that the fuel is 17 months old there was rust in the filter. Even after you get tge tank out and clean the inside add some good treatment to the fuel 911 would not hurt along with some 2 stroke oil. All info that you have helps us help you.
this is diesel fuel, not gasoline. shelf life for diesel is several times longer than gasoline. which should also run after 17 months. i think diesel in a drum would be good for 7-10 years or something like that.
the truck started knocking when this fuel was new.
the rusty filter has been changed to a new filter.
the only thing im wondering is if there was water in the fuel when the guy refueled the truck. (maybe he got a bad tank of fuel)
i know i sound like i dont know what im talking about on here, but im not all that wet behind the ears, just with diesels.
i tried to shut off each cylinder with the efi live, but it didnt seem to work correctly? engine would change its note slightly, but the "buttons" in the software never changed or highlighted when clicked. i could click on all 8 and the truck would not cut off.
Like you said your not wet behind the ear just with the diesels thats why your here asking? and a common rail diesel is no gasser.Added some info on diesel fuel below for you.
Diesel Fuel Quality is a Question not a Guarantee
Diesel engine designs striving to increase engine performance have made great advancements in engine fuel delivery to the combustion chamber. Today?s diesel engine is quieter, smoother, and more powerful. But today?s diesel engine owners are overlooking one important factor. The quality of today?s diesel fuel has not advanced at the same rate as the engine improvements. Diesel fuel begins to deteriorate as soon as it is produced. Within 30 days of refining, all diesel fuel regardless of brand, goes through a natural process called re-polymerization and oxidation. This process forms varnishes and insoluble gums in the fuel by causing the molecules of the fuel to lengthen and bond together. These components now drop to the bottom of the fuel tank and form asphaltene also known as diesel sludge. The fuel begins to turn dark in color, smell bad, and in most cases causes engines to smoke. The engines smoke because some of these clusters in the early stages are small enough in size to pass through the engine filtration and into the combustion chamber. As these clusters increase in size, only part of the molecule gets burned. The rest goes out the exhaust as unburned fuel and smoke. With increases in cluster size they begin to reduce the flow of fuel by clogging filters. The filters only address the symptom and not the cause.
It is estimated that eight out of every ten diesel engine failures have been directly related to poor quality and contaminated fuel. The build-up of contaminates in the fuel systems and storage tanks can quickly clog filters, thus resulting in engine shut down, fuel pump wear, and diesel engine damage.
Understand that most fuel has some amount of water in it from either condensation or vents. This threat requires that we realize the added burden placed upon diesel fuel as opposed to gasoline. Gasoline acts as a fuel only. Diesel fuel, on the other hand, also must cool and lubricate injection ystem parts. These parts are engineered to very close tolerances - up to 0.0002 of an inch - and any contamination means rapid part wear. Water displaces the diesel fuel. When the fuel is displaced wear occur because lubrication is now absent.
this truck had a self loading repo body on it, but i believe the previous owner said it came with a bed on it and was converted by an outside company. not sure what the title means, maybe box truck?
i ordered one of the $30 deals from harbor freight. little did i know, it was shipping out of california. which just so happens to be one of the farthest places away from me. lol
should be showing up here this friday. i HOPE to get some time to work on it sat. and sunday. ill keep you guys posted.
p.s. fuel tank has been emptied and ready for fresh fuel.
UPDATE-
10 gallons of fresh diesel is now in the tank along with a bottle of stanadyne.
truck still runs the same.
fedex dropped off my pos chinese harbor freight compression tester and my dad and i managed to get the drivers side cylinders checked. they all produced over 425psi, and #8 got up to 480psi with some extra cranking. (gauge kept easing up) anyways, i think they are all pretty close to one another. keep in mind the drivers side is where my problem #2 cyl. is located. (with the high balance rate)
i never found a way to disable all the injectors on the engine using a fuse or relay. aparantly im the only person in history to do a compression test on an LBZ. lol i wound up unhooking all the injectors for the drivers side. i also did not notice any fuel spraying out of the cylinders during the testing. (would indicate a hung open injector) we are going to test the pass. side cylinders tomorrow.
back to the $30 harbor freight gauge many are using.... what a piece of junk. the dmax fitting may work ok on an LB7, but it BARELY works on an LBZ. you can only get it in the head 3-4 threads if your lucky. the hex part at the top will come in contact with the head once its threaded those 3-4 threads, so you cant keep your socket on there. it will push itself off the hex. once you get the fitting in the head and begin cranking on the engine, 50% of the time the quick disconnect will blow itself off somewhere around 400psi. i wound up holding it on by hand as my dad cranked the truck. once youve read your gauge, you cant release the pressure because the button doesnt work. the little shoulder screw in there seals on the o-ring, so the button is just a pneumatic cylinder instead of a bleedoff.
JUNK!!!!
10 gallons of fresh diesel is now in the tank along with a bottle of stanadyne.
truck still runs the same.
fedex dropped off my pos chinese harbor freight compression tester and my dad and i managed to get the drivers side cylinders checked. they all produced over 425psi, and #8 got up to 480psi with some extra cranking. (gauge kept easing up) anyways, i think they are all pretty close to one another. keep in mind the drivers side is where my problem #2 cyl. is located. (with the high balance rate)
i never found a way to disable all the injectors on the engine using a fuse or relay. aparantly im the only person in history to do a compression test on an LBZ. lol i wound up unhooking all the injectors for the drivers side. i also did not notice any fuel spraying out of the cylinders during the testing. (would indicate a hung open injector) we are going to test the pass. side cylinders tomorrow.
back to the $30 harbor freight gauge many are using.... what a piece of junk. the dmax fitting may work ok on an LB7, but it BARELY works on an LBZ. you can only get it in the head 3-4 threads if your lucky. the hex part at the top will come in contact with the head once its threaded those 3-4 threads, so you cant keep your socket on there. it will push itself off the hex. once you get the fitting in the head and begin cranking on the engine, 50% of the time the quick disconnect will blow itself off somewhere around 400psi. i wound up holding it on by hand as my dad cranked the truck. once youve read your gauge, you cant release the pressure because the button doesnt work. the little shoulder screw in there seals on the o-ring, so the button is just a pneumatic cylinder instead of a bleedoff.
JUNK!!!!
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Did you clean all the fuel lines on the truck also from the tank to the cp3 and back to the tank.Its helps removing the fuel rails and cleaning those and the the feed lines to the each injector..
i didnt disassemble the fuel system, but i did let it sit and idle for a bit to circulate the fresh fuel through. it never sounded any different or got any better at all. ill be doing the passenger side compression test here shortly, and ill let it idle some more. also will check the filter for any water.
the fuel that came out of the tank looked fine, with no signs of water or anything like that. i believe it was ok. at this point if the rest of the compression test looks ok, im going to point my finger at the ecm. i tried unhooking the plugs for the ecm as well as the tcm and blowing them out with air to check for foreign material in the pins, but they seem fine. the ecm itself fires the injectors, correct? maybe one of the output transistors for the #2 injector has taken a crap in the ecm? im not sure if i mentioned it in a previous post, but this truck has quite a few burned out bulbs all over it, and many popped fuses/incorrect fuses in the fuse panels. i had to buy 2 packs of 10a fuses to get all those straight. im wondering if someone may have hooked a 24v charger up to this truck at some point?
the fuel that came out of the tank looked fine, with no signs of water or anything like that. i believe it was ok. at this point if the rest of the compression test looks ok, im going to point my finger at the ecm. i tried unhooking the plugs for the ecm as well as the tcm and blowing them out with air to check for foreign material in the pins, but they seem fine. the ecm itself fires the injectors, correct? maybe one of the output transistors for the #2 injector has taken a crap in the ecm? im not sure if i mentioned it in a previous post, but this truck has quite a few burned out bulbs all over it, and many popped fuses/incorrect fuses in the fuse panels. i had to buy 2 packs of 10a fuses to get all those straight. im wondering if someone may have hooked a 24v charger up to this truck at some point?
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If the ECM was screwed most the time it would not run. There could be junk in the high pressure fuel lines feeding the injectors or in one of the rails it self block it's supply to the injector. It's happed to other trucks on here finding junk in the rails. Have you checked to see if the oil has any fuel mixed in it with the balance rates it has? I think you need a few new injectors.
how do i find the injectors it needs? efi says cyl #2 has a high balance rate. the service manual says a high balance rate on any given cylinder means a bad injector or low compression.
cyl #2 has good compression and a brand new injector. its balance rate is still super high. its feed line was cleaned out, and i purged the rail before hooking the feed line back up.
the engine runs fairly smooth, as if all the cylinders are firing ok..... but one is knocking like a mofo. the passenger side cylinders had good compression #s as well. engine oil is slightly high, but doesnt really smell like diesel is in it. there was no water found in the fuel tank when it was removed. going back to the beginning of the problem, the guy said he was driving it along when it started knocking faintly. i would tend to think several injectors would not have failed at once?
cyl #2 has good compression and a brand new injector. its balance rate is still super high. its feed line was cleaned out, and i purged the rail before hooking the feed line back up.
the engine runs fairly smooth, as if all the cylinders are firing ok..... but one is knocking like a mofo. the passenger side cylinders had good compression #s as well. engine oil is slightly high, but doesnt really smell like diesel is in it. there was no water found in the fuel tank when it was removed. going back to the beginning of the problem, the guy said he was driving it along when it started knocking faintly. i would tend to think several injectors would not have failed at once?
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When you did the compression check did you have all the glow plugs out at the same time. Also did you unhook the the injectors and glow plug controler to keep from getting fuel in the bore you were testing. Also it would not hurt just to send off all the injectors to a shop that can test them and rule them out there rates area werd with your 1 St post some high some low some the same I take it that was done in park what do they read in drive with tge brakes on.
we tested with all the injectors unhooked and glowplugs removed from each side. the glowplug module was still hooked up, however. there was no fuel spitting out of the glow plug holes.
that log i posted was done in park like you said. i'll see if i can get one in drive with the brakes on.
that log i posted was done in park like you said. i'll see if i can get one in drive with the brakes on.
Sounds good Also it's hard to find some paper towels that work good for this. Take a paper towel pull the oil Dipstick let a drop of oil drip on it and see if you get a lighter colored outer ring color then the center dark oil spot can help see if you have fuel in the oil also.
thought of something else... im trying to come up with a theory here. going by the firing order, cyl. 1 fires right before cyl. 2....
if cyl. 1 injector is restricted and doesnt squirt much fuel, engine rpm would fall off a bit and cyl. 2 would try to pick rpm back up with a large blast of fuel? and this large blast of fuel could mean a balance rate of 11, which would also make a fuel knock?
in other words, im wondering if i may have a problem with the cyl. 1 injector?
if cyl. 1 injector is restricted and doesnt squirt much fuel, engine rpm would fall off a bit and cyl. 2 would try to pick rpm back up with a large blast of fuel? and this large blast of fuel could mean a balance rate of 11, which would also make a fuel knock?
in other words, im wondering if i may have a problem with the cyl. 1 injector?