QSM11 turns but won’t fire

[Richard OFerrall]

I just overhauled the water pumps on two QSM11 (635) in a Luhrs 41. Glendenning electronic throttles and shift. After re-fitting the overhauled pumps, the starboard engine starts and runs fine, everything normal. But the port engine rotates when the starter is engaged, but won’t fire.  When the port engine circuit is energised, the LCD engine display screen boots up, but the engine warning light module is dead and doesn’t run a self test. After booting up, the port Engine display screen shows dashes instead off zero in the RPM slot, then after initially displaying “SYSTEM OK” it switches to “DATA LINK INACTIVE”. The engine display screen also shows dashes in all the engine parameters instead of current readings for coolant temp, oil pressure, etc. When the starter is energised, the engine starter engages and cranks the engine, but the engine doesn’t fire, so clearly, the fuel cutoff solenoid is preventing fuel being scheduled. All fuel lines and valves are open, plenty of fuel, no filter problems, and everything was operating normally when the pump was removed just three days prior. It looks like an entire wiring loom is disconnected or inoperative. Everything was working fine before the pumps were removed. I’ve been over every loom and connection I can find, disconnecting and refitting them all, including the inputs to the Glendenning module in the engine room. I can’t find any hidden fuses to check. Given the above symptoms, it surely has to be electrical, and almost certainly an entire loom rather than a loose single wire.  Any ideas…?? And thanks in advance… Rick

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[Edward Coyman]

The Fort Myers Cummins shop did an excellent job of diagnosing the problem. Turns out to be a bad ECM module mounted to the port engine. As a final test we swapped the ECM from the starboard engine and it started right up. So the mystery is solved.

[Edward Coyman]

So I ran a hot wire (12 volts) from the positive battery terminal and touched the single wire post on the fuel solenoid on the starboard engine, which I know is running fine, to hear the sound of the solenoid as it opened and closed. Then I did the same to the non running port engine and heard the same sound, so I do believe that the solenoid is functioning just fine on the port engine. The problem is that no electrical current is reaching the solenoid. Did another check of all wires, connections and anything I could see that may be hampering electrical current. No luck.

So I am now throwing in the towel and requesting the Cummins dealer in Fort Myers travel to the boat with the diagnostic computer to see if they can find something I am missing. Its an hour and a half drive each way.

They have a several week backlog so I out of luck for a bit.

[Edward Coyman]

QSM11 with no power to fuel solenoid

I will certainly examine the back of the 5Amp breaker connection points when I test the solenoid with a hot wire from the battery. Thank you for that suggestion.

My boat is largely a 24volt system on the DC side, but when I put a multimeter on the wire to the solenoid of the starboard engine (good engine) with the key on it reads 13.4 volts so the solenoid must be a 12 volts version.

Will test this week and report back next steps.

 

[Richard OFerrall]

My apologies Edward… I missed the dead circuit narrative. I also had similar symptoms once and it was a failed key circuit. The red 5-amp circuit breaker on the left side of the block is the so-called key circuit, and while the breaker was OK, one of the two contacts at the back of that breaker had corroded and the wire had broken off the pin connection at the back of the breaker. So again, with that beaker failed or the circuit broken with a corroded wire, the engine won’t start.

[Edward Coyman]

QSM11 with no power to fuel solenoid

I can certainly try to replace the fuel solenoid on the port engine.

But, I am still perplexed over why no electrical current is coming out of the network to feed the solenoid.

I have two solenoids on each engine. One at the top of the tank that activates a fuel cut off valve and the one on the engine at the fuel pump. There is no current going to either of them which means they are on the same network. So I understand that the mechanics of a solenoid can fail inside but I would think that the wire that feeds it should still show an electrical current. In my case no current.

On the starboard engine, both the tank solenoid and engine solenoid show power with the key on and it runs fine.

My next test was to run a hot wire directly from the battery to the fuel solenoid on the engine to see if I can hear it click open.

 

[Richard OFerrall]

Problem identified and fixed

Hi Edward… we did extensive troubleshooting and research and came up with the following:

We switched over ECMs, connected a laptop with troubleshooting software, but everything showed normal except the engine still wouldn’t run. We did hear/feel the solenoid on the good engine “clunk” as it worked normally when the ignition was turned in, whereas the solenoid on the bad engine did not make the “clunk” as ignition was turned on, so had apparently failed closed.

When the ECM is working normally, and batteries connected, it still sends 12v out constantly, with no circuits turned on, this residual voltage is normal.

So the problem was definitely the fuel solenoid, which had failed internally, and when it does so, it shuts off fuel as a fail safe mode. The weird voltage across the solenoid is just one of the symptoms of an internal failure. The result is that the key circuit still gets powered up and thinks everything is OK, so the engine cranks, but the solenoid stays closed, and the only indication (no fault codes either from the ECM, or even the laptop troubleshooting software) is the “Engine Fault” light, which indicates a non-fatal fault, and the failure to fire.

Anyway, we changed the solenoid out and the engine fired and ran normally.

One trap in the process that we discovered was that the square-shaped O-ring that comes from Cummins in the box with the new solenoid was about 0.5 millimeter too small in diameter, so when we first fired up the engine with the new solenoid, the engine fired and ran normally, but fuel sprayed out everywhere from the joint where the new solenoid attached to the fuel pump. We shut the engine down, removed the new O-ring, replaced it with the (undamaged) old O-ring, started the engine again, and all fixed. 

So when you replace the solenoid, just look very carefully at the thickness of the O-ring that comes in the box with the new solenoid, because the one that came with my new solenoid was not suitable for my engine. Whether that’s something that varies and Cummins changed the spec slightly at some stage, maybe Tony would know, but it’s a nasty trap and a fire hazard.

[Edward Coyman]

QSM11 with no power to 24V fuel solenoid

I have the exact same problem.

When I use a multimeter on the one wire going to the fuel solenoid at the engine fuel pump location there is no power. This is my port engine. It cranks but will not start. ECM powers up. Sometimes it will read Data Link Inactive. The analog dials will often slowly spin/rotate 360 degrees around the dial.

The Smart Craft harness was new 3 years ago and the ECM was also replaced at that time. Has been no issue with them for several years until now.

Boat has been laid up for 18 months for various repairs and upgrades to paint and interior. 

During that time power was off and batteries disconnected.

Any suggestions? I am in SW Florida.

[Tony Athens]

Well, it’s been a month……..Have you resolved to “no-start issue?

[Author]

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