1987 mercruiser 340's acting weird

[B BARKER]

Turned the port engine on and nothing, all gauges not working, starb fine. Then tried again gauges all come up it started and gauges working ran for 30 seconds quit, gauges not working then the gauges come back on fires back up runs for 30 secs quit again, does this about 5 or six times then ran ok all day long. Noticed port heat gauge is a little hotter than usual trying to heat up especially while idling but good flow out of exhaust ? Could a bad temp sender be causing all of this ? Any ideas...........B. Barker

 

[SCORPIO]

It sounds more like a bad main ground or some kind of short. I can't see a bad temp sender doing anything more than causing no/bad readings on the temp. gauge. I'd start at the battery and work backwards. Be sure to clean the main ground on the back of the engine and be sure it's tight. Also, take a look at the primary connection at the starter solenoid, make sure its clean and tight also. Could also be a bad connection on the ignition switch or a failing switch internally. A test light or volt/ohm meter will be a big help.

 

[Mike Blake]

OR all where it starts. Properly test the batteries first. Save a lot of headaches

 

[B BARKER]

Thanks guys for your thoughts....I definitely found the heating problem I figured I better check the raw water pump and the impeller is shot so I got that out to rebuild checking out the grounds next...Thanks B.B.