Engine electrics mystery

[rafiki_]

Fired up the port engine OK. Tried starboard, and nothing. Thought it was flat battery. Turned port engine off and starboard running.......Nothing on the gauges, revs, oil pressure etc. Turned it off, and tried again. Absolutely nothing...dead as a Dodi. Checked batteries, and they were ok. Disconnected batts then reconected...nothing. Port engine still OK. Tried the outdrive tilt, this was OK. Starboard engine then cranked and started. Gauges also OK, but no engine alarm (bleeps until oil pressure OK). Engine ran fine, with gauges OK etc. Engines are Merc 1.7 DTi's, non electronic.

Any views?

Puzzled of Stratford.

 

[timtap]

The plug and socket on the engine loom may need the contacts cleaning ??

 

[rafiki_]

I don't think there is an engine loom. It is a DI non electronic engine, manual fuel pump and injectors. I think there must be an inhibitor somewhere that needs looking at, but don't know where to start with this.

 

[timtap]

You should have a wiring harness between the engine and control panel , a plug/socket at the engine and at the panel. Also there are often on many if not all Mercs a red cut-off button on the side of the engine .

 

[Harpsden]

Had a similar intermittent problem on Volvo D3s eventually traced to a faulty battery isolator switch with the contact breaking down under heavy load.



Harpsden

 

[Firefly625]

Could it be a starter solenoid on its way out.

 

[rafiki_]

Some interesting posts. Why would a small change in outdrive trim make a difference?

 

[Firefly625]

yep, strange... just re-read issue again... and why didn't the engine oil pressure alarm sound when the engine finally started.... /forums/images/graemlins/confused.gif

 

[spannerman]

Check your battery connections at battery and starter, also engine earth, the trim pumps on mercruisers are wired direct to the battery unlike volvo, so will always work.

 

[rafiki_]

Firefly,

My thoughts too. I removed both pos and neg straps on the starboard batteries, and also the buzz (earth) bar.

I guess I'll have to contact CMD service to see if they have any suggestions/experience on this.

 

[atlowers]

We needed both battery banks on to start on seasonal debut this Monday. I noticed a significant drop on the vltmeter when adjusting trim. Now wonder if this is normal as not spotted it before. Interested to know what CMD say. Please post if they come up with answer.

 

[rafiki_]

Tried Cummins at Southampton, but no real joy, so will contact their field service rep. Will let you know of the outcome.

 

[John100156]

It does sound as if its a faulty or high resistance connection somewhere, the outdrive tilt could be misleading, but then again it may not, if this start sequence can be repeated!

Could it be a corroded ignition/engine start switch? Can you try another or temporarily by-pass it?

I suppose you could use a volt meter along the starting line to see if there are any significant and/or unusual volt drops, or an amp meter to see if something is dragging the voltage down, but with that amount of energy being dissipated I am sure you would find this type of fault if that were the case (something would burn-out!).

I would check all connections and strip down and inspect any line components such as switches, relay contacts and the like and perhaps the starter solenoid/motor!

Be interested to know what you eventually find.

Best of luck getting this sorted! /forums/images/graemlins/frown.gif