Cat 3116 died during cruise; won't start

[Z-Worthy]

So we were out for a sunset cruise tonight and everything was running fine for about 45min. We were mostly cruising between idle and 1300; cocktail speed. After about 45min, the port just died in the blink of an eye. No loss of rpm, no strange behavior, no warning, just dead. It'll turn over all day, but never even caught one single time after it died. Where should I start with my diagnosis here? I know it has to be fuel, but seems odd that it went so quickly.

 

[ttmott]

Sounds like the fuel solenoid shut off.
When you toggle the start switch to the on position do you hear a noticeably audible "click" on the engine?
If you don't it's the fuel solenoid or power to the solenoid. There is a relay(s) that drive that fuel solenoid and 9 times out of 10 that relay fails. There were two configurations for that relay one which is in a white electrical box on the engine and one (earlier version) without the electrical box. Seems there was a posting and thread on this exact issue a couple of weeks ago.

 

[cwiert]

Sounds like the fuel solenoid shut off.
When you toggle the start switch to the on position do you hear a noticeably audible "click" on the engine?
If you don't it's the fuel solenoid or power to the solenoid. There is a relay(s) that drive that fuel solenoid and 9 times out of 10 that relay fails. There were two configurations for that relay one which is in a white electrical box on the engine and one (earlier version) without the electrical box. Seems there was a posting and thread on this exact issue a couple of weeks ago.

Yup. That was my thread. Here it is...some good info on solenoids and relays.
http://clubsearay.com/index.php?threads/starter-solenoid-for-3116.83801/

 

[ttmott]

If you have the junction box here is a picture of it and that relay of interest. Here is a link to a suitable replacement relay https://www.waytekwire.com/item/75311/Bosch-Tyco-332209137-High-Current-Mini-Relay-/ or NAPA would have a relay that will work; just make sure it has a minimum current rating of 30 amps.

 

[Blkbird]

+2 on the fuel solenoid relay. I had both of mine go out with a month.

 

[Z-Worthy]

So I went down this morning prepared for battle. Hopped on the boat and just for kicks tried to start it. FIRED RIGHT UP! Ran for 30min, moved it over to our regular dock, been sitting here letting it idle for another 30min. Seemingly running completely fine. Now I'm more confused than ever!

 

[Blkbird]

Yep. And when the relay gets hot your engine will be starved for fuel and die. Mine used to cutoff when I was on the plane, and then start back up again. Sometimes.

 

[Z-Worthy]

There were two configurations for that relay one which is in a white electrical box on the engine and one (earlier version) without the electrical box.

So it appears that I do not have the electrical box on my '97 (at least I do not believe I see one anywhere). So where would these relays be located on my engines if I don't have the junction box? I did a cursory run-through and they aren't anywhere obvious.

 

[fwebster]

There is one more part and possibility here. Refer to ttmott's posts # 2 & #4........in Post #2, Tom mentions an audible click when the starter button is depressed. That click occurs when the "fuel shut off solenoid" opens. It is triggered by the Bosch mini relay shown in post #4. The fuel shut off solenoid is part #2 in the drawing below and is located on the lower forward postion of the injection pump. It requires a special pin wrench Caterpillar part # 9U-5120) to remove and install.

If you do not hear that audible click, the problem is probably the Bosch mini relay, but given your description of shutting down when hot then not restarting until cool, the problem may very likely be the fuel shut off solenoid itself. You will need to check the voltage on the terminals on the end of the fuel shut off solenoid to verify that the Bosch mini relay is bad if there is no audible click when the start button is depressed. No voltage = bad Bosch mini relay; voltage = bad fuel shut off solenoid.

 

[ttmott]

And, this is that J-Box. If you don't have it on your engine then the solenoid may be powered only by the ignition switch and no relay at all.

 

[Z-Worthy]

So I definitely don't have that J-Box on my engines. And I also do not see any relays anywhere. So I'm guessing my problem is the fuel shutoff solenoid. Now for the fun part: how difficult is it going to be to locate one of these solenoids? Pretty standard part or very specific?

 

[ttmott]

Well, like Frank says above you need to make sure the solenoid is, in fact, the problem. It could be the wiring from your start switch also. So like he posts above verify battery voltage at the two wiring terminals on that solenoid when your switch is on. Mess around with the wiring and connections to make sure they are good and not a contributor to your intermittent issue. Also, your switch on the helm may be going bad.... I suspect they went to the relay to take the electrical current that solenoid demands away from the switch.

And the solenoid are very standard and should be easily available at your Cat service center; or order it on line.

 

[Z-Worthy]

I'm struggling to truly identify the problem because everything is seemingly fine right now. I can't duplicate the issue; engine fires right up and stays running without any load. And it's too windy this weekend to get out and run a test; if it goes down again I'll never get back into the dock on one engine. So I guess I just have to wait for a calm day and get out in the open and see if it happens again.

 

[Boat Guy]

Z, I would probably prepare to replace one, if not both shutoff solenoids. It might not be the issue but it can ruin your day if it fails at an inappropriate time.

Here is a link I came across... https://www.mechanicshub.com/toolbox/cat-3116-fuel-shutdown-solenoid/

 

[Z-Worthy]

Thanks for all the awesome responses and informative links!! This forum is fantastic for topics like this. But my mechanic managed to trace the whole problem to a loose connection on the positive lead. Now if only all of my repairs could be this cheap and simple...

 

[The Bill Collector]

Before I replaced the Bosch relays I made up and still carry a fused wire with clips on each end.... 12v positive battery to the positive side of fuel solenoid. You really hear it snap back to the open position with the fused jumper wire and standing right there. Remember though to shut down that engine you'll have to go down there and remove the fused jumper wire.

 

[Z-Worthy]

Before I replaced the Bosch relays I made up and still carry a fused wire with clips on each end.... 12v positive battery to the positive side of fuel solenoid. You really hear it snap back to the open position with the fused jumper wire and standing right there. Remember though to shut down that engine you'll have to go down there and remove the fused jumper wire.

So your protocol would be to go connect the jumper to the battery, connect the jumper to the solenoid (hear the click), climb up top and hit the starter switch to get the engine running, go wherever you're going, climb down and disconnect the jumper to shut the engine down. Correct? I'm going to steal your idea and make one of these over the winter, just in case. That's a GREAT idea!

 

[The Bill Collector]

So your protocol would be to go connect the jumper to the battery, connect the jumper to the solenoid (hear the click), climb up top and hit the starter switch to get the engine running, go wherever you're going, climb down and disconnect the jumper to shut the engine down. Correct? I'm going to steal your idea and make one of these over the winter, just in case. That's a GREAT idea!

That's exactly what I have done when I had to use the jumper wire... Be sure to identify the positive side, I took a felt marker and put a big plus on the positive side.

 

[Max]

If you have the junction box here is a picture of it and that relay of interest. Here is a link to a suitable replacement relay https://www.waytekwire.com/item/75311/Bosch-Tyco-332209137-High-Current-Mini-Relay-/ or NAPA would have a relay that will work; just make sure it has a minimum current rating of 30 amps.
View attachment 50303

I have the electrical box as shown on my cat 3116 engines. Sometimes after I do a slow speed cruise and shut the engine off, it will not start. I do hear a click when I engage the start switch. The last time it happened I blew cool air in the box and then it started so it is some component overheating. Problem is I don’t know which part to replace. Any suggestions?

 

[carterchapman]

Max - for less than $10, I would replace that Bosh Tyco Relay listed above. They are available at most auto parts stores...