Random cutting out 4.3 mercruiser

[dalkaveli]

The temp is on the front of the intake and has 2 wires
The diode is most likely the Red plug. The more I think about it, its not the diode

Ohms read 960 at cold. Seems functional.

 

[alldodge]

The temp sensor is a switch. its open below 110* and closes about 130*

From manual 41 the TKS module test Ambient Temp
70* = 35 - 45 ohms
20* = 55 - 70 ohms

If the 960 ohms is from the TKS then its out of range but doesn't indicate a excess current issue. Might take longer to warm up

If its the Temp then there is an issue

 

[dalkaveli]

Being TKS might have an issue with the Temp switch, diode or TKS module.

Anyone of the above if it starts drawing more current, may drain power from the coil

This could be coincidence but I started messing around with the harness that’s attached to the TKS module and the bundle going elsewhere. I can’t readily reproduce, but it seems like it wanted to drop more consistently after I was messing around with the wiring around that area but it wouldn’t do it every time or immediately and now is running fine...

This connector is really hot. Is the diode we discussed earlier? Do you do you know what it does? One end goes into the fuel pump.

 

[dalkaveli]

The temp sensor is a switch. its open below 110* and closes about 130*

From manual 41 the TKS module test Ambient Temp
70* = 35 - 45 ohms
20* = 55 - 70 ohms

If the 960 ohms is from the TKS then its out of range but doesn't indicate a excess current issue. Might take longer to warm up

If its the Temp then there is an issue

Temp at 155 on gauge, the ohms are .13 after 5 minutes. My volt meter was set at 2k

 

[alldodge]

That's the diode

 

[alldodge]

Temp at 155 on gauge, the ohms are .13 after 5 minutes. My volt meter was set at 2k

Wrong sensors, that is the gauge sensor
The TKS temp switch is on the top front side of the intake
TKS module is on the carb

 

[Scott Danforth]

If the diode is 155F, check for bad connection there.

 

[dalkaveli]

So I looked at this again with a mechanic. All the suggestions here were explored but it only died once in fifteen minutes. Same thing after cooling off an hour later: died once within warmup at idle. Might be weird but seems like after it warms up 10-15min it is less likely to occur. I drove it around for an hour no issue. Something is causing ignition system to cut out but all connections are clean and ground is as it should.

Could this be the ECU by chance? Only other thing can I think of is the harness. Though I'd think shaking it would cause the issue to reproduce and it doesn't.

 

[alldodge]

It takes 10 to 20 minutes from motor cold for the TKS module to totally retract. That's the only thing right now that would take about that long

 

[dalkaveli]

It takes 10 to 20 minutes from motor cold for the TKS module to totally retract. That's the only thing right now that would take about that long

So is there ever a scenario where the tks enrichment or sensor would cause an issue with the ignition system? We've checked all wiring in the ignition system (except harness internals) and replaced or tried other parts within the ignition system. It still will lose voltage and turn off. Typically once before tks warms up. Diode and enrichment solenoid are receiving voltage. The boat will lose voltage entirely and stop with volt gauge going to zero, few seconds go by and it goes back to normal and can restart. 3rd gauge from left in video.

Battery cables, starter solenoid, and coil are new as well

 

[alldodge]

Reminds me of a auto rest breaker. The ones which trip when heat builds then reconnect when they cool down. If it has one then it could be its tripping at a lower amp rating. Find the fuse/breaker on the Red/Purple wire going to the key switch. See if its a regular type or a auto rest

 

[dalkaveli]

Reminds me of a auto rest breaker. The ones which trip when heat builds then reconnect when they cool down. If it has one then it could be its tripping at a lower amp rating. Find the fuse/breaker on the Red/Purple wire going to the key switch. See if its a regular type or a auto rest

It's a standard 3 fuse. It’s actually a red and purple wire separately spliced into the ignition with the red the only one going to that fuse. The purple runs up to a harness.

 

[alldodge]

That's not the ignition fuse, might be the stay alive power 3 amp. Ignition will be at least 15 amp

 

[dalkaveli]

That's not the ignition fuse, might be the stay alive power 3 amp. Ignition will be at least 15 amp

Sorry wouldn't let me revise. There's also a red ten amp that's not resettable. It's attached to two red with black stripe wires

 

[alldodge]

That's probably it
Place a meter on one side of the Red/Purple or Red/Black of the 50 amp breaker. The other side of the breaker will come from the starter post and should be solid Red.

Trying to find out maybe the breaker is trip/resting. It shouldn't but might be

 

[dalkaveli]

That's probably it
Place a meter on one side of the Red/Purple or Red/Black of the 50 amp breaker. The other side of the breaker will come from the starter post and should be solid Red.

Trying to find out maybe the breaker is trip/resting. It shouldn't but might be

Do you mean the reset amp on front? It's a 20. This I replaced recently as well. I can check all with meter.

 

[alldodge]

No its on the motor
https://www.amazon.com/50A-Marine-Circuit-Mercruiser-32V/dp/B00DP04ZNA

 

[dalkaveli]

No its on the motor
https://www.amazon.com/50A-Marine-Circuit-Mercruiser-32V/dp/B00DP04ZNA

Ugh yes my bad. I'm underway. I suspected this at times. Thanks for all your help. I'll check it at port soon.

 

[dalkaveli]

Ugh yes my bad. I'm underway. I suspected this at times. Thanks for all your help. I'll check it at port soon.

I wasn’t able to reproduce the issue today with meter hooker up
...and to add to the perplexity, the diode started smoking and a hole burnt through it. It was very hot. Never seen that one before. Maybe the temperature switch is revealing it’s true nature? At the time it smoked I took an ambient reading of the temp switch and it was 156 fahrenheit

 

[alldodge]

You have a short, so is it the module or pump, guessing module