Mecruiser 7.4LX MPI Ignition System Issues . . .

[tpenfield]

I did some clean up work on the ignition switches this morning. Easy access by removing the panel



The connections and the wiring looked OK . . .



I removed the screws on each connection at the switch, then cleaned the contacts and re-assembled. Then buttered them with electrical grease.

The main connectors had plenty of grease in them already and they looked OK.


I cleaned up the wiring a bit and put it all back together.



I still could not find any inline fuses, and I would think that they would be located near the ignition switches. I also took a look at the circuit breaker connections and those seemed to be well greased and in good condition.

Of course, the engines started up without issue, but there is no telling if that will be the case going forward. IF the problem persists, I will probably work my way back to the engine bay and check connections and grounds in that area.

It seems that electrical issues are often tough to track down.

 

[tpenfield]

Well, a little bit of time has told the story, at least more of the story . . .

Starboard engine has difficultly engaging the starter . . . I am now consistently getting the 'beeps', but the starboard engine does nothing when I turn the key to start . . . no clicks or nothing. Port engine is working fine.

So, I'll be checking more connections, etc. as I work my way to the engine room. One thing that occurred to me is that maybe it is the starter solenoid that is the problem :noidea:

One other thing that seems a bit unusual and may be related, is that the voltage seems to be running a little high . . . 14+ volts . . . (normally is 13.5 ish) . . . and the oil pressure and temp gauges seem to be running a little lower than normal. . . not too much, but enough to be noticeable.

 

[alldodge]

Your getting the beeps so computer says all is good to go. I'm thinking the slave solenoid, mine went out a couple years ago and gave me fits until I found it.

 

[achris]

14v is the recommended charging voltage (14.2 to 14.5). Depending on the load (electrical), the distance between the engine and the voltmeter, the gauge of the wire, and the accuracy of the gauge, anything in the 13 to 15volt range could appear. The only way to be certain of the actual alternator output is an accurate (Fluke?) multimeter on the output terminal of the alternator...

As a diagnostic tool, put an LED (with appropriate resistor) on the 'S' terminal on the stater solenoid. When the problem occurs, if the LED's on, the problem is the starter, if not, it's elsewhere....

Chris.......

 

[tpenfield]

Thanks AllDodge & Chris . . .

Last year, the solenoid on the port trim pump went out and behaved in similar fashion . . . got finicky, then finally gave it up all together. So, I'm thinking the solenoid at this point, but probably will check all the other connections as well.

We did a fair amount of boating yesterday and went to multiple places. In total, I probably had to start the engines a dozen times. The starboard engine always got the 'beep' but often took several attempts with the key to get the starter to kick in. Port engine was fine throughout.

Still not sure why my gauges would read lower and the voltage gauge read a bit higher (even though it is in an OK range, I am just noticing recent changes). I would think that a bit more voltage would have the temp and possibly the pressure gauges reading a bit higher. I know that the temp gauge goes up with more current running through it, but not sure about the oil pressure gauge.

Ben Franklin should have left more instructions when he discovered electricity . . .

 

[tpenfield]

Update . . .

I replaced the solenoid on the starboard engine and checked the other connections. The solenoid seemed to do the trick. So, that might have been the major issue, but the port engine was putting up a fuss initially.. Maybe that was solved by freshening up the connections. :noidea:

So, we will have to see how it goes.

 

[alldodge]

Update . . .

I replaced the solenoid on the starboard engine and checked the other connections. The solenoid seemed to do the trick. So, that might have been the major issue, but the port engine was putting up a fuss initially.. Maybe that was solved by freshening up the connections. :noidea:

So, we will have to see how it goes.

If there is no change then maybe replace the port engine later and keep the old for back up :thumb:

 

[tpenfield]

A quick update: This past weekend we did lots of boating, tubing, etc. with many starts and stops of the engines. Everything seemed to be OK. So, I think it was a combination of cleaning up the contacts on the connectors to the switches and replacing the starboard solenoid. :thumb: so. Looks like the boat is good for now, until something else breaks.

 

[Bondo]

A quick update: This past weekend we did lots of boating, tubing, etc. with many starts and stops of the engines. Everything seemed to be OK. So, I think it was a combination of cleaning up the contacts on the connectors to the switches and replacing the starboard solenoid. :thumb: so. Looks like the boat is good for now, until something else breaks.

Ayuh,... Glad to hear ya got it sorted out Ted,....