Engine won’t stay running at startup

[Ltyrell1]

I have a 2001 mainship pilot 30 rum runner with a 250 hp Cummins diesel. When I push the start switch the engine starts, but as soon as I remove my finger from the switch the engine stops running. If I hold the switch in the start position it will continue to run until I remove my finger from the switch and the engine stops. I repeated this procedure several times and the engine finally stayed running. The problem seems to be intermittent, as some times the engine will start right up like it should. Could this be a fuel issue or electrical?

 

[fgarriso]

It sounds like the shut down solenoid is being activated

 

[RT Firefly]

Greetings,
Welcome aboard. I've seen this problem posted on TF before BUT I will have to rely on the memory and expertise of my fellow members to provide expert guidance.
Trust me. The memory isn't the first thing to go....

 

[Comodave]

Welcome aboard.

 

[Lepke]

Depending on your wiring, you may have a sensor failure or either a short or failure in stop solenoid wiring or the solenoid itself.
If it was my engine, I would disconnect the stop solenoid and manually start the engine by attaching a button or switch between the starter solenoid battery cable post and the small start post. Or touch a screw driver across. The engine should start and continue to run. Then it's an electrical problem to sort out.
In the picture between the right post and the tab at the top. Your starter solenoid may look different.

 

[STB]

Sounds like fuel....low idle setting, reatriction, top solenoid, or air.

As others have said, check the stop solenoid if the engine has one, which can restrict fuel flow, first.


How does it run at the slip once started? What happens if, upon starting, you advance throttle (in neutral) a bit and then let go of starter? Maybe the idle is off?

How does it run once underway? If low power observing, maybe a fuel restriction...filter or valve closed?

Maybe an injector went bad? Once running on its own (without needing to hold starter), try checking for a bad injector.

 

[RT Firefly]

Greetings,
Mr. Lt. To add to Mr. L's post (#5). The start button he is referring to is similar to this: https://www.oreillyauto.com/detail/...rter/lis0/20750?q=remote+starter+button&pos=2
Quite a useful tool IMO and it's only $20 or so.



Personally, I would would make every effort to not short the starter/solenoid with a screwdriver or wrench etc. It could damage terminals.

 

[Ski in NC]

Some Cummins engines the fuel solenoid "pull in coil" is energized from starter circuit. The "hold coil" (much weaker) is energized by the ignition switch.

So if it is wired that way, and it starts with starter roll and then quits, look for a fault in the ignition circuit.

A 250hp could be a few different versions. Which injection pump? CAV, Denso, Bosch??

 

[STB]

Relaying a comment that was made to me in a DM...

The engine runs fine once it starts (and stays started).

That being the case, I guess I'd like to know the engine model, because the next place I'd look really depends on how fuel supply and shutoff works.

I want to guess a fuel supply solenoid hold coil, but I don't know if the engine has one and, even if it does, can't quite sort out why it isn't sometimes stopping ot shuddering once running.

 

[kapnd]

Some Cummins engines the fuel solenoid "pull in coil" is energized from starter circuit. The "hold coil" (much weaker) is energized by the ignition switch.

So if it is wired that way, and it starts with starter roll and then quits, look for a fault in the ignition circuit.

A 250hp could be a few different versions. Which injection pump? CAV, Denso, Bosch??

On some of these pumps, the linkage is exposed, and can be held open with a finger or a rubber band to help track down the source of the problem.
Others just have a wire connection at the bottom, make sure that’s clean and solid.

 

[AZ2Loop]

Ltyrell1, some good ideas above. Whatever it turns out to be, please circle back to the forum and let us know. These threads are so helpful for other boaters that find the thread in the future -- but far more helpful if the solution is posted. Good luck, and hopefully it will be simple.

 

[C lectric]

Likely electrical. Ski has a good point but you need to fill in which injection pump you have for him to further help.
The fact that the engine starts and runs untill you release the START position back to the run position would indicate to me there is a problem with the start switch losing continuity when you release it. The fact it is intermittent suggests even more strongly it is the RUN part of the circuit. It could be a bad contact in the switch, loose wiring or poor connections or a failing hold coil in the fuel control solenoid.

But we need some help from you to be able to help you further.
Have you made any further progress?