Cummins 6bt starting issue

[C lectric]

'Power to run' means that if you have an electrical failure the engine will shut down. A faulty fuel control solenoid could shut you down, one lousy loose wire. Think about a rough sea or you get in the way of a much larger vessel or are travelling a current ridden or narrow passage. More than one boat came home after an electrical failure as long as the engine was running or could be started with an independent battery. Often as a backup with this setup people have rigged a mechanical means of closing the fuel valve.

Don't get me wrong as this is what I have, power to run.

'Power to stop' means once started the engine will continue to run regardless of whether the electrical system fails or not. On a boat this is usually an advantage.


If you truly have a runaway engine the fuel solenoid will not stop it anyway. Usually the fuel the engine has found has bypassed the controll, such as crankcase oil. The diesel control solenoid can do nothing. In a case like that the only way is an air shutoff which has to be rigged to operate before a situation like this occurs. Runaways are much less likely with the 4 cycle engines than with the 2 cycles.

 

[jleonard]

'Power to stop' means once started the engine will continue to run regardless of whether the electrical system fails or not. On a boat this is usually an advantage.

Was doing some work last weekend on the boat in the slip and was adjusting the upper tach. When I went below to shut down I had nothing...engine kept running.
So I shut her down manually by movng the lever by hand.
So if you have a "power to stop" setup you should learn how to stop manually.

(problem was I broke a connector off the upper start switch when I was behind the panel. Easy to find/fix thankfully)

 

[Rekindle]

I've had 2 different Cummins 6BT's for many years. Touch the start switch and she's running. Every time I think she's getting tired because the start time gets longer I change out the battery and I'm back to 2 second starting. I've been amazed at how she really likes a good fresh battery. Is your first (quick) start straight off the shore power/charger?

 

[35RivieraSplashgordon]

After many many dead ends, my mechanic spoke to a mechanic in Florida that had the same issue. Not electrical, not fuel. The starter selenoid plunger is "binding" and not returning to the proper position after a cold start. I'll try to get a more detailed description once fixed but by manually moving the plunger on the selenoid prior to ignition, starts right up without the delay in fire up even when warm. After selenoids Are replaced I'll report back if that ends this crazy making problem. Always started fine when cold or when I let it cool for 3 hours. I hope this solves it.

 

[Xsbank]

There are 2 start solenoids on a Cummins, the normal one we all have on the starter and an "auxiliary relay" that caught me by surprise when I had my starter out for a refresh.

 

[Ski in NC]

After many many dead ends, my mechanic spoke to a mechanic in Florida that had the same issue. Not electrical, not fuel. The starter selenoid plunger is "binding" and not returning to the proper position after a cold start. I'll try to get a more detailed description once fixed but by manually moving the plunger on the selenoid prior to ignition, starts right up without the delay in fire up even when warm. After selenoids Are replaced I'll report back if that ends this crazy making problem. Always started fine when cold or when I let it cool for 3 hours. I hope this solves it.

Go see the test proposed in post #7.