Mariner 60, 3Cyl Dies and dies again

HughN · 16 July 2013, 12:30

My 1991 Mariner 60, 3Cyl, 2-stroke has let me down today.

It needed lots of 'fast idle' to get it to start and idle. Once it was warmed up I gave it a run and after about 15 minutes it came to a halt. Despite being warmed up, it needed more 'fast idle' to start it again and it kept happening over and over again - stop, restart, run for a few minutes, stop.

The fuel primer bulb remained solid.
There is no water visible in the fuel filter/separator.
The fuel is less than a week old and it was previously left with the carb drains out and a good dose of carb cleaner sprayed through.
It revved at 5600 rpm at WOT for ages without any problems, so it wasn't 'bogging'.
IMHO it stopped slightly more smoothly than if the kill-switch had been pulled.
It was a bit 'tink-tink-tink' at times as it came to a halt, but that might have been the transmission being back-wound by the prop.
The overheat warning didn't go off.

This evening I'm going to check the plugs, leads and fuel line, but is there anything else that I could/should check whilst doing so before I start adjusting carbs / timing?

If the mixture is off, does it sound more like too rich than too lean? It needs more air to start and idle, but would all three plugs foul at the same time?

SWMO was on board and now trusts neither engine or boat - hence my aim to get it running well and use it whilst she still won't want to accompany me.

Thanks
Hugh

TRevor Lawson · 16 July 2013, 21:32

Hi If by moving the fast idle lever on your engine you are giving it more air, then it suggests it's too rich and fouling plugs, also idle and bypass jets may be blocked if it runs wot ? check fuel tank breather and air filter as well.do you know the fuel is good and not contaminated? have had dodgy fuel from pumps.just a few thoughts.

Pedrode · 16 July 2013, 23:01

Quote:

Originally Posted by HughN

My 1991 Mariner 60, 3Cyl, 2-stroke has let me down today.

It needed lots of 'fast idle' to get it to start and idle. Once it was warmed up I gave it a run and after about 15 minutes it came to a halt. Despite being warmed up, it needed more 'fast idle' to start it again and it kept happening over and over again - stop, restart, run for a few minutes, stop.

[*]The fuel primer bulb remained solid.[*]There is no water visible in the fuel filter/separator.[*]The fuel is less than a week old and it was previously left with the carb drains out and a good dose of carb cleaner sprayed through.[*]It revved at 5600 rpm at WOT for ages without any problems, so it wasn't 'bogging'.[*]IMHO it stopped slightly more smoothly than if the kill-switch had been pulled.[*]It was a bit 'tink-tink-tink' at times as it came to a halt, but that might have been the transmission being back-wound by the prop.[*]The overheat warning didn't go off.

This evening I'm going to check the plugs, leads and fuel line, but is there anything else that I could/should check whilst doing so before I start adjusting carbs / timing?

If the mixture is off, does it sound more like too rich than too lean? It needs more air to start and idle, but would all three plugs foul at the same time?

SWMO was on board and now trusts neither engine or boat - hence my aim to get it running well and use it whilst she still won't want to accompany me.

Thanks
Hugh

I have the 2004 vintage of this engine. Two issues I have had with mine which sounds vaguely similar: first was operator error....when I forgot to open the breather! What amazed me was how long the engine had run for with the breather closed - at least 15 mins. Second was a leaky thermostat which caused the engine to idle very poorly and then stall (because it was never at the right temperature) and needed a lot of choke / fast idle (same lever on mine) to re-start even when it had been running for a while - but it only stalled when idling, never running at speed. The good news is that the new thermostat has transformed the engine...when I remember to open the breather on the tank! My guess though from your description would be fuel starvation.

HughN · 17 July 2013, 07:54

Thanks for the replies - I do need to sort the idle issue. However, I would like to nominate myself for "Plonker of the Year, 2013".

It would appear that my mind kept thinking about this whilst I was asleep. I woke this morning knowing what the problem was.

At the time, my wife was moaning that she was getting wet from inside the boat as well as from outside. ("Silly woman - that's not possible")
My 11yr old daughter noticed that the speedo was indicating about half what the GPS said.
A huge amount of water drained out of the boat (I put this down to the extra weight of my wife in the back seat keeping the bung below the waterline!)

Checking this morning and, yep, there is a split in the hose from the speedo pick-up to the speedo - where it passes behind the electrics for the controls. They are mostly heat-shrink waterproof connectors but not all of them and in any case there would have been water everywhere and like a garden hose was spraying on it.

Water + electrics = short = killed engine. It was then stopping again because as soon as the boat started moving again more water was being sprayed on the electrics. Engine stops. No water being sprayed.

A nice easy fix though!