CAT 3126TA 350hp Won't start when hot

Mystic Dreamer

Mystic Dreamer

Active Member
Oct 10, 2006
392
St. Petersburg, FL
Boat Info
2006 44DA
Engines
Cummins QSC-500
Back in the fall I bought a 2001 380DA with 350 HP CAT 3126TAs (400hrs). The boat has been great, but recently I noticed a problem emerge. If I take a relatively short ride, let the engines warm to temp, and then shut them off, the starboard engine won't start. I first suspected a fuel issue so I changed the racors. Wanting to go out twice today, the first time (engine cold) no problem- second time, engine warm, it won't start. I will have a CAT mechanic look at it, but wanted to see if anyone had any thoughts. Should I switch fuel tanks and see if the problem shows up on the port engine?
 
Why experiment, or get stuck someplace. I would wait until it is checked out. Maybe Frank W. will have better advice for you.

Good luck.
 
Cranks without starting or does not crank. Details help.
 
If the cranking speed is normal, then she should start if she's got fuel. Is there power on the shutdown solenoid when hot?

Best regards,
Frank
 
This isn't a fuel issue, or rather a fuel filter issue so I don't think changing tanks is going to hlp anything.

I am also assuming that the cranking speed of the engines is the same whether they are hot or cold. If your cranking speed is lower when the engine is hot, it may not be turning fast enough to ignite the fuel. This one isn't likely, but if it is, the cause is a bad starter motor or loose/corroded starter connections.

Your most likely cause is a sticking or faulty fuel run or supply solenoid. It could also be a loose wire on the fuel supply solenoid. Find the fuel distribution pump.....outboard side of the stbd engine where the throttle cable connects....look for the only thing near it with a single wire (small like a # 12) connected to it...lightly tap the body near the wire with a mallet or small hammer while cranking.
 
Well, while we'er waiting for the tech heres a wild guess. For cold starting the engine needs fuel enrichment. For warm start no fuel enrichment. This is usually controled by an eng temp sensor. My wild guess is that there's a sensor that's going open when wamed up. If that's true we just need to where it is. Remember this is a WILD guess.

Andre'
 
Thanks for the replies so far- Fast cranking on both motors, whether hot or cold, so I can rule that out.

Frank, I think your on to something with the solenoid. When I hit the port motor, I hear a "click" before pushing further to start. On the starboard, (problem engine) no click.

I researched a little on boatdiesel.com and some old searches came up with worn injectors as the problem. I hope it's the solenoid.

Brian
 
Some of that stuff on boatdiesel.com will give you heartburn. With 400 hours, the only thing on your engines that have any noticable wear is going to be the seawater pump.

This isn't your problem, but there is a very important service that must be done on 3116/3126 engines at 250 hours......resetting the engine overheads., i.e. adjust the valves and the injectors. If you have a Cat technician coming to the boat, and you don't know if this service has been done, ask him to do it while he is there. Its about 8 hours work but it may save your engines since the valves get tighter, not looser, as the engine wears in. When the valves get tight, you can have one hit a piston and on a diesel that fires at 23:1 compression the result is not pretty.
 
Yes, already on the schedule for next week is the valve adjustments and transmission services (and fixing of the issue). FYI, when I bought the boat I had new water pumps put in, new raw water hoses, heat exchangers rod cleaned, oil services, fuel filters, zincs etc. Although the survey and oil samples turned out fine, I want to do as much "preventative" maintenence as possible.

This board is awesome!
 
You are about done then..........after this little gotcha and the valve adjustment go boating and enjoy the some of the best running diesels Sea Ray ever put in boats......gotta love the 23 gph at cruise.
 
"resetting the engine overheads"........................................OOps better get that done then, didnt know it was as important as that !
 
Here is the update: I called the CAT tech a few weeks ago and explained the "no click" sound from the fuel shutoff solenoid and he agreed that it should be replaced, which was done. The starboard engine worked fine until last week when I was coming back from Captiva Island. I stayed the night at Longboat Key and the next morning, with the engines cold, the starboard would not start, and no "click" on the solenoid! Same symptoms as last time- no "click", but a fast crank. Called CAT again, and they said since the fuel solenoid most likely was not the problem. He thought it could be two things- a wiring issue or possibly the halon system module was trying to shut down the engine. Anyway, at his instruction, I put the halon system on overide and I played with the connections in the junction box (back side of the motor with all of the wires in it), and it fired up! This got me back to my house where the next morning- nothing. The CAT tech was back today and said that the relay in the junction box was bad so he replaced it. Engine starts just fine. Good news is that a new relay is only $19, so I had him replace both port and starboard.

Hopefully that its on this issue!

Brian
 
Glad to hear that you found the problem, but you need to understand that paying $19 for a marine repair will anger the boating gods. Watch out for lightning strikes. (good idea to do both, but $38 will still make the skies rumble!)

:)
 
Ahhh, I should clarify- $19 for part, but labor and trip charge, much more! And I did replace the fuel solenoid- $200 for that plus labor and trip charge!

Relatively small price since I just burned $1000 in fuel on this last trip to SW Florida! (But glad it was not $2000 in gas)
 
Mystic Dreamer said:
Ahhh, I should clarify- $19 for part, but labor and trip charge, much more! And I did replace the fuel solenoid- $200 for that plus labor and trip charge!

Relatively small price since I just burned $1000 in fuel on this last trip to SW Florida! (But glad it was not $2000 in gas)
Click to expand...

fc3 said:
If the cranking speed is normal, then she should start if she's got fuel. Is there power on the shutdown solenoid when hot?
Click to expand...

That's why one diagnoses before swapping parts. At least it was a cheap lesson.

Best regards,
Frank
 
I guess my real lesson learned is let the professionals handle what I don't have any clue about. However, my problem first was that the engine would intermittently not start when warm. Since I could not reproduce the problem on demand, I did my best to explain it to the CAT tech (when he arrived at the boat it fired right up over an over). Like Frank W said, the tech believed it was a faulty fuel solenoid, so I agreed to replace it. In hindsight I guess I could have waited until the problem came back and then checked for power to the solenoid (before calling the tech).

Well, just relieved to be back boating!
 
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