Engine running very rough QSB 5.9L

[dhays]

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?

 

[Bruce B]

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

 

[dhays]

That was my thought as well Bruce. There are a bunch of connections there. I will see about inspecting each one.

 

[Bruce B]

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.
Bruce

 

[dhays]

Yeah, I thought I had blown an engine on a 94 RX-7. It ended up just being a loose plug to the ECU.

 

[North Baltic sea]

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!

 

[stone beach]

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!!!

 

[North Baltic sea]

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?

 

[sunchaser]

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.

 

[Conall63]

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.

Conall

 

[dhays]

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.

 

[cardude01]

Do those new QSBs have an ECU where you can pull the codes? That's always where I start on my vehicle engine diagnostics.

 

[Ski in NC]

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.

 

[MYTraveler]

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.

 

[sunchaser]

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?

 

[Ski in NC]

Knocking, shaking at idle, any exhaust smoke white/grey/black. Should "purr" at idle.

 

[dhays]

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.

 

[ktdtx]

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.

 

[dhays]

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.

 

[Irish Rambler]

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.

 

[Ski in NC]

There is a crank position sensor right in front of sea water pump on left side of engine, it counts teeth on the crank damper wheel. Make sure that thing is aimed right and that it has a good connection.

 

[Baker]

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.

I do not think this is good advice for a common rail engine!!!

 

[Lepke]

On older engines that control the injectors mechanically, rough running is usually a stuck or plugged injector. The injector often will clean itself after a short run. I have seen small 3 & 4 cylinder) engines sound like a rod knock that was a dirty injector.
The newer electronic controlled engines have sensors that can go bad, temporally or permanently, plus can have bad contacts, bad ground, bad controller, all difficult to trace and diagnose. That's why I have Detroits.

 

[dhays]

There is a crank position sensor right in front of sea water pump on left side of engine, it counts teeth on the crank damper wheel. Make sure that thing is aimed right and that it has a good connection.

Ski, that is something that Corey at Seaboard recommended I look at as well. I did have to take off the belt cover to remove a floor panel and it is certainly possible that I had knocked it when crawling around. It will have to wait until the weekend though unfortunately and I have some work to do on my sailboat as well.

Working sure gets in the way of boating.

 

[dhays]

I do not think this is good advice for a common rail engine!!!

Yup. Great advice Irish but not for the type of engine that I have.

 

[North Baltic sea]

Hi dhays,


did you find what caused the rough running your QSB? I have the same engine, and therefore interested to learn new things and Cummins.


NBs

 

[Irish Rambler]

Hi dhays & Baker.
Ooops I did my Merc CDI and she's flying, maybe she'll crash ?

 

[Baker]

Hi dhays & Baker.
Ooops I did my Merc CDI and she's flying, maybe she'll crash ?

Nah...totally different animal!!!

 

[FF]

"That's why I have Detroits."

On our 6-71 I remove the air box cover (one bolt) and spray fogging oil into each cylinder for over 30 day storage.

A half hour at worst and a HUGE!!! amount of smoke on the next start up.

 

[dhays]

Hi dhays,


did you find what caused the rough running your QSB? I have the same engine, and therefore interested to learn new things and Cummins.

Did you ever sort your rough running QSB?

Update, short version:

I called the local diesel shop and scheduled a mechanic to come out and look. Short version, they think it is a faulty lift pump. A new one is scheduled to be installed next Friday.

Longer version:

The mechanic hooked up the laptop to the ECM and the only codes it was throwing were for a fault in the lift pump. Since I know nothing about diesel engines, all I knew was that the engine was running rough and sounded terrible, he said is was a "fuel knock". On Friday, after a few minutes it would smooth out and idle quite nicely with only the very occasionally hiccup. However until then it sounded horrible. The kid said that he had a new lift pump sitting on his bench at the shop waiting to go into the exact same engine as I have.

Anyway, it was the only thing he could find from the ECM and he checked all the connections I had been concerned about and said they were all fine. He actually said they all look in new condition. Hopefully, this is the answer and it will fix the problem.

Longer rant version:

Tacoma Diesel has been the go-to shop for marine diesel work in the the Tacoma/Pierce County area for a long time. They are a Cummins certified shop as well as a certified shop for a bunch of other brands. I called them and spoke to Kurt the service scheduler and made an appointment for this last Friday. BTW, it took two calls to get the appointment made. The first time Kurt said that they had a lot of jobs in and that I should call back later in the week to see if they could schedule an appointment. This was a few weeks ago. Anyway the mechanic was going to be at the marina at 9:00am. I was there and ready by 8:30am.

At 9:40 I called Tacoma Diesel since no mechanic showed up. I spoke again to Kurt. Turns out Kurt had sent the mechanic scheduled to check out my boat away on an emergency commercial job. He forgot about me and didn't call. He apologized. What he didn't do was provide a solution. I told him that I was not happy and asked how he was going to solve his problem of forgetting a service appointment that he had on his own calendar. He finally agreed to find someone to send out and found someone while I was holding on the line. He would send them right out. He called back about 15 minutes later and said that the mechanic he was sending had to go pickup one of the shops laptops at another job. It would be another hour.

So at 11:00 the mechanic shows up. It turns out it was the same kid that showed up last year to remove my aftercooler for servicing. Almost the same thing happened last year. I had mad an appointment with Kurt for the job. Last year I called the day before to confirm only to have Kurt tell me that the experience mechanic who was to work on my boat he had just sent to AK on a commercial job the day before. I now think that he would have forgotten about me if I hadn't called him first last year. The kid he sent had been working with them for all of two weeks.

So the kid, now a year more experienced, seemed more familiar with my engine than he had last year. While he seems very competent, and I like the guy, he doesn't have the level of familiarity with the Cummins line that I would like. He does have some great backup however at Tacoma Diesel and did call a seasoned mechanic a couple times to kick around some ideas. Turns out this kid had worked on my slip neighbors boat a couple weeks ago.

Anyway, last year I let the scheduling issue go as a simple mistake that can happen in any business. I own a business and I know how things can happen at times. However, I have had the same experience now 2 our of 2 times. Not a good track record. I get the impression that Tacoma Diesel is focusing its service work on the commercial sector and large yachts and have less interest in the pleasure boat side of the service business.

So I will likely send the owner and email. I know him and think I owe him that much, but I am going to be looking for another shop to handle my repair and service needs. If anyone has some recommendations in the Tacoma/Pierce County area, I would appreciate it.