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Old 02-18-2017, 04:26 PM   #1
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Engine running very rough QSB 5.9L

i started the engine today after a bit of time without running, a couple months. In the meant time the only thing that has been done to the engine was adding a pan heater and changing the zincs.

Today the engine started up fine but was running extremely rough. It gradually smoothed out but now occasionally it will sound like it again seems to be fine.

I don’t know engines at all so am at a loss. I will say that the Smartcraft display is reading a fuel burn rate that is way too low. When installing the pan heater, I was working around the electrical connections on the port side of the engine. Is it possible that I disturbed one of those? If so, any suggestions on which to check out?
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Old 02-18-2017, 04:40 PM   #2
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Without being familiar with this engine at all I will fall back on a theory that has served me well in my professional career, look at the last place you worked! Or look at the place/places you last touched. Odds are you disturbed something.
99% of the time this is where you will find the issue.
It is always possible that you simply moved something that was destined for failure anyway. Some wire that was ready to part or even a connection that was tenuous anyway so don't feel too bad before you figure it out.
Bruce
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Old 02-18-2017, 04:50 PM   #3
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That was my thought as well Bruce. There are a bunch of connections there. I will see about inspecting each one.
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Old 02-18-2017, 05:09 PM   #4
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That was my thought as well Bruce. There are a bunch of connections there. I will see about inspecting each one.
Quick story...
I once purchased a used Saab 9000 from a new customer who came to my shop at the end of his rope with the car. It seems that when parked the car and restarted it while still warm it would on occasion run so rich that it would flood.
He had been to a bunch of shops trying to find the issue and he had spent as much in repairs as he had spent to purchase the vehicle new!
This over about 6 years and without ever finding the cause of the issue.
Anyway, when he brought it in to us it needed some oil leaks repaired and brakes and he said "enough!".
I purchased the car for myself knowing that it had a mystery illness that could surface at any moment. The car was a delightful thing to drive and I loved it. Finally about 2 months after I purchased it it acted up.
It was so rich that I knew there were just a few things that had that kind of authority over fuel mixture, mechanical devices being ruled out as having been replaced numerous times in the vehicles history.
One thing on that vehicle that could force the fuel system to be incredibly rich was the engine temperature sensor. In very cold weather conditions these things push a lot of fuel when first started.
So, I began at the temperature sensor and began inspecting the wiring harness. About 5 minutes into my inspection I found a multiple pin connector that had been assembled at the factory and never disturbed as evidenced by the unique tie wrap used during assembly. I cut the tie wrap and unplugged the connector to find the problem! A misformed wire terminal that when heated disconnected. A quick reforming with a pair of needle nose pliars and reassembly fixed the vehicle of that problem forever. I drove that car another 100,000 miles before selling it.
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Old 02-18-2017, 06:28 PM   #5
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Yeah, I thought I had blown an engine on a 94 RX-7. It ended up just being a loose plug to the ECU.
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Old 02-19-2017, 03:25 AM   #6
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Hi dhays,


I came to the idea of ​​the wrong quality of diesel. do you have a different quality of cold air. In Finland, we have four quality diesel summer, mid-season - 15 ° C and winter quality -38 C° and arctica -44 C°precipitate functional. diesel containing paraffin which consists of crystals in the cold. these - ° C grades of paraffin removed something additives. paraffin mayby shut the filter, shut to the pump and then spray nozzles can get clogged (shut).
When the fuel heats up the whole system, the crystallization of the paraffin wax is removed and is soluble in a liquid form again.


if you have cold air and summer-quality diesel, I believe this has caused a rough ran your qsb, du you know a fuel in the tank in a temperature and quality?


If you see Racor filter the display of the meter it is the filter is shut (paraffin) chek this first!

I hope the reason to be that simple, if possible to heat the fuel tanks of more than + 5C °, this problem should arise even if the summer grade diesel fuel.


these ideas diesel grades here. I can not feel the US diesel grades, you can find out from someone who knows more in-depth US diesel fuel.

Kippis!
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Old 02-19-2017, 05:15 AM   #7
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If same layout as last one I worked on you have been working around the ecm and fuel pump. Lots of connections around there. DONT START PULLING THEM APART. You are very likely to put another fault on making trouble shooting much more difficult. If its working ok now strongly advise you leave things alone. If / when it acts up again gently "massage" the connector blocks in that area one by one until you find the one that clears the problem, maybe none will...in which case its likely a sensor problem not connected at all with your oil heater workings. In this case the "massaging" won't help you....but that should have given you an error code???
Hope this helps...hate electronic engines!!!
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Old 02-19-2017, 06:55 AM   #8
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You can read cold and diesel fuel broblems this link, i think this is yours cummins broblems this time, i hope...


Diesel In Cold Weather - Diesel Engine Problems - MyCleanDiesel.com




diesel fuel, fridge cooled 40f/4C° you can see whithe sediments under fuel, maybe your filters, tank and pipes etc same sediment?


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Old 02-19-2017, 08:27 AM   #9
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How about leaving the dock and running the vessel at high cruise RPM for awhile? If not done in the past year, change your fuel filters first. Could be nothing more than too much slow running prior to docking and winter idling at dock.

The temperatures in the Seattle area on the water aren't that cold, certainly not like N Europe or the US NE.
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Old 02-19-2017, 08:28 AM   #10
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How cold of a temperature was it when you started it? It sounds like a cold related condition. Ive only used block heaters which plumb into the coolant circuit, and have never used a pan heater. Is it possible the pan heater isn't doing enough to heat the engine up? With a block heater on a sub zero morning, when you stand next to the truck, you can hear the coolant moving around the engine via convection. If the engine was hot enough from the pan heater it should start as easy as it normally does on a 70 degree day.

Diesels need fuel and compression to run so the chances of you having disturbed something electrical are slim... Not to say it's not an electrical issue, but most electrical issues on modern engines are failures in code or issues with the ECM. But there again, fuel and compression are the biggies.

I would try the cheap things first such as changing filters.

Algae can grow in fuel and quickly plug filters.

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Old 02-19-2017, 12:05 PM   #11
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Thanks for the ideas guys.

It is very unlikely that it is a cold weather issue. Simply put, our weather is never that cold and it wasn't cold yesterday.

The engine did smooth out some but would still falter periodically, maybe once every 2-4 minutes. The other thing that leads me to think it is an electric problem is that the smartcraft fuel burn reading is way low. Filters look good. No recent fuel fills.
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Old 02-19-2017, 12:23 PM   #12
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Do those new QSBs have an ECU where you can pull the codes? That's always where I start on my vehicle engine diagnostics.
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Old 02-19-2017, 12:30 PM   #13
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Be careful with this. A common rail engine running strange and showing lower than normal gph may have an injector sticking open. This can burn a piston quickly. Get a tech down there with the Insite laptop and have it checked out.
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Old 02-19-2017, 01:01 PM   #14
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Quick story...
Here is my quick story. I bought a new Ford Bronco, years ago. Early in its life, there was a problem solved by the dealership's replacement of sparkplugs under warranty. That problem was solved, but by summer a new problem had arisen -- the air conditioning was anemic. The cold air was merely cool. I took it to the dealer, they kept the car over night but told me they fixed it. But, it soon became apparent that the problem persisted and under cross examination the dealer admitted that they hadn't fixed anything, they merely confirmed that cold air was coming out. Reluctantly, they had me bring it back. This time, the mechanic put a temperature probe in the vent and again pronounced the system fixed. I took the car, but nothing had changed and again the service manager fessed up that they had merely confirmed that cold air was coming out. The service manager claimed there was not spec, and could be no spec, since it was humidity dependent. He refused my request to measure the temp on a new car and washed his hands of it. So, I suffered with crappy AC for several years. When it was time to sell the car, my brother had a friend who was interested. I told my brother the story, he took a quick look and easily diagnosed that a heat shield between the cold side of the freon line and the exhaust manifold had been moved out of place to get access to the spark plugs. He moved it back and it was like a whole new car. But my last Ford.
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Old 02-19-2017, 01:04 PM   #15
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Be careful with this. A common rail engine running strange and showing lower than normal gph may have an injector sticking open. This can burn a piston quickly. Get a tech down there with the Insite laptop and have it checked out.

Excellent point Ski. What other things can show up indicating a sticking injector on a CR engine?
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Old 02-19-2017, 01:18 PM   #16
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Knocking, shaking at idle, any exhaust smoke white/grey/black. Should "purr" at idle.
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Old 02-21-2017, 01:19 AM   #17
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Great advice Ski. The Cummins Smartcraft display on mine finally did show an error on the way home this afternoon. All it said was "Check Engine". Not very helpful. I can't even find any documentation where the Smartcraft will give such an error message.

I still think that I may have disturbed on of the electric bits on the port side of the engine. Another possibility mentioned by Corey at Seaboard is that it could be the sensor that monitors the speed and position of the crankshaft. Its location is such that I could have disturbed it.

No smoke at all, just the engine missing a bit and the gph reading is about 1/2 to 1/3 of what it should be.

If I don't find something obvious, I will get a mechanic down to find it and fix it. I hate to spend the money, but that would be cheaper than some major engine work.
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Old 02-21-2017, 11:06 AM   #18
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My QSC 8.3 story (still ongoing) engine would intermittently run rough and wander +/- 200 RPM and fuel flow would vary with it.. By intermittently I mean not even every day of cruising. I chased it around as a fuel problem-filters, etc-no real improvement.

Then one day when it was happening I went into engine room to "look". I put some outboard pressure on the large wire bundle on the port side...everything smoothed out.

Then I put inboard pressure on the bundle--RPM would decrease and engine would stumble to the point I felt I could have shut down the engine if I maintained the pressure. I did this a few more times and same happenings..Voila...problem diagnosed!! I wired the bundle with outboard pressure until returned to Anacortes..seemed to run better.

Well, not so fast!
Got the Cummins Tech on the boat..nothing on computer, no faults, nothing when manipulating the wire bundle while he was on the boat. Could not reproduce the problem in a 2 hour sea trial.
He recommended an injector flow test. I'm skeptical but did it. All injectors removed, sent off and all failed 1 or more tests.

Still ongoing because boat on land, shrink wrapped and injectors not yet replaced with new (only 1700 hrs on engine) so not sure this is THE problem or the only problem but it is A problem.
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Old 02-22-2017, 02:20 AM   #19
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Thanks Ken.

I still think my problem is related to the electrical connections in that bundle on the port side. The only think that changed with the engine is that I moved those around when I was working in that area. Now, I hate it when my patients insist that since problem A started when situation B occurred that there has to be causal relationship between the two. Even so, in this case I think there is a real relationship.
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Old 02-22-2017, 03:55 AM   #20
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Often if engines are laid up or not run for months they will fire up uneven and after a few minutes run smooth.
If the fuel lines have not been disturbed nine times out of 10 it will be a sticking injector.
Run the engine until warm, remove the fuel filter, drain the diesel and refill the filter with injector cleaner, start up on tickover and let it run on tickover for about 5 minutes, then take it for a spin gradually building up the load until WOT for 15 minutes, then reduce the revs gradually. ALWAYS let a diesel engine run on tickover for 5 minutes after running hard this helps to relieve 'hot spots' by thermal dissipation.
Add injector cleaner to the existing fuel in the tank.
If you remove the injectors for repair over winter spay fogging oil or WD 40 into the cylinders and close with tightly rolled paper towel.
Cheapest place to get your injectors is usually an agricultural dealer.

I only have cdi on the Merc car so have no experience to offer.
I hope this helps someone.
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