Mariner 90hp Trim Guage

[TheKarnicKid]

Hi,after fitting genuine Mercury Trim Guage and sender i finally got the guage to register,only to find that when i switch the ignition on/off with the outboard down,the guage needle rapidly goes off scale
both ways,tapping glass will restore it.Cycling the ignition when outboard up, guage seems fine.Once ign on and needle reset,guage behaves as normal.
As part of the diagnosis i bench tested the new parts which behaved perfectly.The only 'extra' fitted since Trim guage fault is a Genuine Votmeter,which i disconnected to prove that's not the issue.
I'm now suspecting loom between motor and boat?Ground for the new sender is now at the engine casing,i did run a test ground direct from battery in initial checks,perhaps re-connect that next?
Would appreciate any comments especially if anyone has had similar problems.kind regards.

 

[TheKarnicKid]

update on trim guage!only six months later!remote unit trim switch playing up recently,ohms check showed ok,tested ignition switch which failed big time.New ign. switch fitted,trim switch treated with contact cleaner and spray grease twice,finally trim guage sorted!
Now trim switch in motor now playing up!Anyone had carbs flooding with this engine?another story i'll put in another thread.