Unresolved problems with Cummins QSB 6.7 liter engine

[Doug_Snider]

At the end of February, we took delivery of our new Helmsman 38E Pilothouse Trawler. We ordered the standard Cummins QSB 6.7 liter 250 hp engine. During delivery from offloading in Victoria, a problem with the engine arose. The engine would shut down a few seconds after starting. During commissioning, the same event occurred. The engine would then run normally after a restart.

On the trip home from Lake Union a new event occurred. As we were approaching the breakwater leaving Shilshole marina, a low fuel pressure alarm appeared on the MFD and the engine abruptly quit. We were able to get the engine restarted as we were drifting toward the rock embankment. The engine ran normally for the rest of the trip home.

A Cummins technician checked the boat out and determined that there appeared to be some leaked fuel on the engine. He made some adjustments. A few weeks later, we were in Port Townsend and the immediate shutdown after starting recurred. Again, the engine operated normally on the way home. A Cummins technician replaced the lower helm electronic engine control that was under a recall. The engine started and ran normally during the course of a one hour sea trial.

A few weeks later we had the low fuel pressure alarm and shutdown while underway. This time we were in the Swinomish channel with a strong current carrying us north. After a more difficult try, we got the engine started. The same thing occurred the next day leaving a moorage on Cypress Island.

We have heard several theories but have not gotten the problem resolved. We are canceling a cruise because we don’t have confidence in the engine and don’t know when or where the engine will fail again.

Has anyone had a similar experience with this engine?

 

[sunchaser]

Dennis Hayes got a new Cummins engine when his NP was having issues. Maybe he'll chime in.

Has Helmsman washed their hands and forced you to deal with Cummins? I'd have thought that the commissioning process would legally not be complete until the boat is seaworthy.

 

[Doug_Snider]

Helmsman hasn't washed their hands of it but getting Cummins scheduled to work on the engine has been a problem. I don't feel that Cummins has done a thorough enough diagnostic to nail down the source of the problem. Helmsman and Cummins are going back and forth while we're going nowhere.

 

[DavidM]

Were all fuel connections checked? Air getting sucked in is the cause of 90% of random shutdowns in diesels. The fact that you could restart also points that way.

Leaks can be hard to find. Sometimes you have to hook up a temporary fuel tank directly to the engine. If it runs ok, then the odds go up to 99% that it is a fuel system leak.

David

 

[O C Diver]

Has Cummins analyzed the engine computer?

I don't have a Cummins engine, my engine is a tier 2 John Deere. As it was explained to me, the computer records everything. As an example, it tracks every so many seconds, what the percentage of load is (my warranty limits the percentage of time the engine is run at100% and above 80%). It was my understanding that the computer also recorded all warnings and shutdowns. Finally, it was my understanding that the complete analysis of all history wasn't accessible buy the dealer, only by the manufacturer. Again, this is what I understood for my John Deere. Assuming Cummins engine computers have similar capabilities, I would think you are entitled to the information why each shutdown occurred.

Any idea if the computer history has been downloaded?

Ted

 

[twistedtree]

Is it Cummins who are coming to the boat, or a dealer? It seems that a low fuel pressure shutdown is either a bad sensor or a bad pump. Also possibly fuel leak down while the engine is off, as DavidM suggests. It's interesting that it only happens shortly after startup. Has the problem reproduced with Cummins on the boat?


It might be worth a call the Tony Athens and a few hours of his time to consult. It's under warranty and the costs should all land on Cummins, but it's your time and use of the boat paying a price too, so probably worth a few $$ if it helps.


Has this been escalated in Cummins? Most fuel techs are poor diagnosticians, and just guess and replace parts. Replacing the control display is a good example. Unless there is a recorded shutdown command, then the display didn't do it. And I doubt the display makes up pressure warnings.



At this point I think the most important thing is to get have the problem reproduce when instrumented with all the factory diagnostics stuff. If you start at the dock and just let teh engine run at an elevated idle, can will it shut down? While waiting to Cummins, I'd work on techniques to reproduce the problem.

 

[Jeff F]

Has Cummins analyzed the engine computer?



I don't have a Cummins engine, my engine is a tier 2 John Deere. As it was explained to me, the computer records everything. As an example, it tracks every so many seconds, what the percentage of load is (my warranty limits the percentage of time the engine is run at100% and above 80%). It was my understanding that the computer also recorded all warnings and shutdowns. Finally, it was my understanding that the complete analysis of all history wasn't accessible buy the dealer, only by the manufacturer. Again, this is what I understood for my John Deere. Assuming Cummins engine computers have similar capabilities, I would think you are entitled to the information why each shutdown occurred.



Any idea if the computer history has been downloaded?



Ted

Ted, my understanding with the same engine was similar to yours, until I started having problems similar to the OP.

There was no trace in the logs of my failures. Eventually I replaced the ECM and all is now good. But there were no diagnostics available from JD to identify the specific issue.

I can't speak to the Cummins, but it wouldn't surprise me if the logs don't help in this case.

I feel for the OP. Without a definitive diagnosis it's hard to be assured that it's fixed.

 

[Doug_Snider]

Is it Cummins who are coming to the boat, or a dealer? It seems that a low fuel pressure shutdown is either a bad sensor or a bad pump. Also possibly fuel leak down while the engine is off, as DavidM suggests. It's interesting that it only happens shortly after startup. Has the problem reproduced with Cummins on the boat?

A Cummins field service technician ran diagnostics and had his computer connected to the engine electronics when we did the sea trial. He wasn’t able to reproduce the event but the fact that it has happened on our last two consecutive trips indicates that it may be getting worse and may be easily reproducible.

 

[Comodave]

I would second the suggestion to call Tony Athens. He is the guru on Cummins. A couple of hours of his time would be well worth it to me to get the boat running.

 

[sunchaser]

Cummins and Helmsman could (and should’ve) been all over this issue. They’ve got several major service centers in WA with their flagship in the area being in Everett. From personal experience I know they are set up to monitor from afar provided Wi-Fi reception is available.

The question is what Cummins Cares group is monitoring this issue.? Then comes is it possibly an install problem from the mechanical, electrical or fuel plumbing side?

 

[Arc]

Helmsman must take the lead on this. It may be an installation problem and have nothing to do with Cummins. They should survey or replace the fuel supply lines form the tank pickups to the last chance filter

 

[jleonard]

Sounds like a fuel line leak to me. Minor leak but enough to cause a problem.

 

[DDW]

The previous model of that engine (QSB 5.9) had problems with the lift pump. I had a similar problem and had to replace it as others did. Engine shut down with a fuel pressure warning, then would restart a few minutes later. I believe the 6.7 has a different lift pump, but still has one.

 

[Delta Riverat]

Fuel on the engine sounds like a leak.

Have you seen this fuel yourself? Does the engine room smell of diesel?

 

[Doug_Snider]

Fuel on the engine sounds like a leak.

Have you seen this fuel yourself? Does the engine room smell of diesel?

We were out of the country when the first Cummins tech worked on the engine. We never saw or smelled diesel in the engine room. I’m not convinced that what he saw was not some residual spilled transmission fluid from the 25 hour fluid change.

 

[Delta Riverat]

Yeah, good call. They're both red.

 

[C lectric]

Red for diesel is not used everywhere so do not assume it is.

I would go and check the fittings of the fuel lines. If fuel got out then the engine, when running, could suck air.

 

[fgarriso]

It sure makes me happy to have non-electronic machinal engines. DD 6-71 engines just keep on running.

 

[Comodave]

Well not if it is an air leak, that will kill even mechanical engines.

 

[fgarriso]

Well not if it is an air leak, that will kill even mechanical engines.

Just tighten the hell out of every thing.

 

[Comodave]

Tighten it up til it strips then back off a 1/4 turn…

 

[utclmjmper]

I like my mechanical 8.3 for the same reason,, it is bulletproof reliable..I had a return fuel leak once and it just kept on running normal except for the mess..>>>Dan

 

[fgarriso]

Tighten it up til it strips then back off a 1/4 turn…

I forgot to back off.

 

[Comodave]

I forgot to back off.

I used to work with an engineer that had that as his operating philosophy. It was brutal coming in and working behind him. Everything was impossibly tight.

 

[Doug_Snider]

Update

The previous model of that engine (QSB 5.9) had problems with the lift pump. I had a similar problem and had to replace it as others did. Engine shut down with a fuel pressure warning, then would restart a few minutes later. I believe the 6.7 has a different lift pump, but still has one.

The Cummins field technician from Everett was on the boat for the third time. He replaced the fuel actuator, after which we did another sea trial. On the previous trial we had not tried WOT. When we advanced the throttle all the way, the fuel pressure dropped immediately, the low fuel pressure alarm showed and the engine began to shut down. After the throttle was returned to idle, the engine recovered. It turns out this engine won’t run at WOT. Why it was never tested is a mystery.

The Cummins tech ran more diagnostics, proposed several more possible causes and made a phone call. After the call, he informed us that he had ordered a new fuel pump. When it will get replaced is unknown.

Possible causes cited:
1. Leak at injectors
2. Faulty pressure relief valve
3. Bad fuel actuator
4. Faulty electronic engine control at lower helm
5. Metal shavings in the fuel system
6. Faulty check valve in the lift pump

Action taken:
1. Tighten injectors
2. Replace lower helm engine control (under recall)
3. Replace fuel actuator
4. Order new fuel pump

We canceled a cruise this week and will likely have to cancel a long planned trip next week with my son visiting from Oregon. Having an unreliable engine on a boat that was delayed four months by a shipping error (it went to the wrong coast) is causing us to question the choices we have made. I don’t think Helmsman or Cummins is giving this the attention it warrants.

 

[sunchaser]

To me the real test of a builder is when things go wrong do they jump all over it. The wrong Coast? Cummins guessing? Where is Helmsman after all this?

A few posts ago it was suggested that Tony Athens opine on the problems. Any joy on this? Helmsman should pony up the plane fare for one of Seaboards guys to fly in. Unless something is unsaid here I see a legal issue or two has arisen.

So sad

 

[Doug_Snider]

To me the real test of a builder is when things go wrong do they jump all over it. The wrong Coast? Cummins guessing? Where is Helmsman after all this?

A few posts ago it was suggested that Tony Athens opine on the problems. Any joy on this? Helmsman should pony up the plane fare for one of Seaboards guys to fly in. Unless something is unsaid here I see a legal issue or two has arisen.

So sad

I posted on Tony Athens’ forum and got a prompt reply. He requested some engine operating data which I haven’t been able to get since we were tied up with the Cummins tech on the sea trial. I provided him with additional information from the sea trial and subsequent repair attempts. I am going to see if I can get a complete report from Cummins.

The wrong coast issue was the fault of the shipping company and Helmsman has made good our delayed delivery. Unfortunately the problems were not discovered until the boat arrived on the west coast and not addressed in time to salvage our summer.

 

[Tim]

Sounds like a similar problem a friend had with his CAT. Fuel tank is below the engine and fuel is pumped up to engine. Apparently when shut down a valve in the Raycor allowed the fuel to drain back into the tank leaving a vacuum in the line which went away when primed. Not sure if there is such a one way valve but replacing the Raycor I think solved the problem.

 

[Doug_Snider]

I'm beginning to think we may have more than one problem. The initial problem of shutting down a few seconds after starting could be the lift pump that brings fuel to the engine and shuts down after the engine is primed. After the shutdown, the engine restarts normally and usually runs without problems. The bigger issue is the engine shutting down underway, especially when adding power. We can duplicate the low fuel pressure alarm and shutdown at WOT almost every time. On three occasions, it has shut down at low RPM shortly after getting underway. Two of those have been immediately after fueling.

Helmsman Trawlers ran tests bypassing the tank and Raycors and running directly from a jerry can. On the initial start in that mode, the low fuel pressure alarm showed and the engine faltered. That may suggest that it is not a problem with the Raycors or the tanks. Switching tanks and Raycors does not seem to make a difference.

I have sent photos and a copy of the Cummins tech's report to Tony Athens who replied very promptly to a post on his forum.

We lost four months due to the shipping Snafu and we have spent another four months dealing with an unreliable engine. We had to cancel a cruise this week and may have to cancel a long-planned outing with my son visiting from Oregon next week. We thought a brand new boat would not come with problems but we were wrong. Cummins has really drug their feet on a solving problem that now seems to be getting worse. Their first two visits were cursory and the actions they took did not seem very logical given the symptoms, tightening the injectors and replacing an engine controller under recall. I'm not sure what the best way to escalate this is. I dread getting attorneys involved. That certainly won't salvage our summer.

 

[FWT]

Am I correct that this is narrowed down to either a fuel pump or air leak in the fuel line between where the Jerry can was rigged and the injector?