IRREGULAR TEMP FLUCTUATIONS - 350 MAG MPI

[thbouro]

On the rear of the engine is an electrical "umbilical" cord that looks a lot like a trailer connector. That cord carries all of your gage signals. I had a problem with an intermittent tach that I solved by unplugging that cord and cleaning all the pins in the connector. worth a shot.

Thanks bobeast, I will try it as soon as I visit my boat!

 

[thbouro]

That's too bad you can't use it. When you get back to it (should only take a few minutes to check t-stat blockage/orientation), post back about that. Keep in mind that hoses don't always supply enough cooling water.

RPM... It could just be loose/dirty connections or even a dirty cylinder-selector switch on the backside of the gauge ("exercise" it a bunch of times to clean it). Check connections for clean/tight statrting at the battery.

Thanks Lazy Daze, wilco!

 

[thbouro]

On the rear of the engine is an electrical "umbilical" cord that looks a lot like a trailer connector. That cord carries all of your gage signals. I had a problem with an intermittent tach that I solved by unplugging that cord and cleaning all the pins in the connector. worth a shot.

bobeast, fyi, yesterday I visited my boat and did what you adviced me; each engine run for about 30 min without any RPM fluctuation, so probably it was the umbilical cord! On the contrary, I noticed again Temp fluctuations, the same as previously, with a trend of lower temp reading, which I suspect was not accurate (lower than 150F compairing to the usual 170F). Next time I visit her I will continue the troubleshooting... (still, any advice is more than welcome!)

 

[bobeast]

bobeast, fyi, yesterday I visited my boat and did what you adviced me; each engine run for about 30 min without any RPM fluctuation, so probably it was the umbilical cord! On the contrary, I noticed again Temp fluctuations, the same as previously, with a trend of lower temp reading, which I suspect was not accurate (lower than 150F compairing to the usual 170F). Next time I visit her I will continue the troubleshooting... (still, any advice is more than welcome!)

peel the problems off like an onion

That cord/plug is a bad design as the only thing that keeps it connected is the band clamp. It recently caused my port engine not to start. Apparently the wires from the ignition switches go through that connector as well. In any case good luck with the next layer of the onion. I got nuthin'