Mariner 75 problems starting from warm

BumbleAbout · 25 July 2011, 12:01

1998 Mariner 75 - new impeller, fresh gearcase oil, new fuel pump diaphragms, clean fuel (added an external filter a couple of weeks ago) - but not sure when it was last serviced properly ...

We went across to the Folly Inn for lunch from Bucklers Hard and it was running fine - but when I tried to restart a couple of hours later, it was a b*gger to start again:
- turned over fine (new battery)
- fuel bulb primer was hard
- occasionally caught and then immediately died

It took maybe ten attempts to start with
a) Pushing the key upwards at the same time as turning it
b) The choke lever pulled fully up

I'm guessing that not enough fuel was getting through (there wasn't a smell of petrol that I would expect from flooded carbs) - any clues what I should do to make warm starting easier in future ?

PS It felt a little lumpy in the Solent on the way back from the IoW at about 17:00 for 3+ a nervous dog in a 4.8m !

spartacus · 25 July 2011, 14:14

You might have fouled the plugs, with the idle lever fully up and giving it plenty choke, given engine should still have been warm. Did the engine sound as if it was trying to catch, or was it simply turning over?

Fuel related: Did you switch fuel tanks and not open the vent fully? There is an internal fuel filter on your engine - check it's clean too.

Electrical related: Might be worth renewing the HT leads. Check you're getting a spark to all cylinders first. Lastly, check the wiring for the stop switch. There's been a few threads regards loose wiring, faulty switch or the lanyard key not fitting properly.

BumbleAbout · 25 July 2011, 15:29

Quote:

Originally Posted by spartacus

You might have fouled the plugs, with the idle lever fully up and giving it plenty choke, given engine should still have been warm. Did the engine sound as if it was trying to catch, or was it simply turning over?.

Initially I had no choke applied - the outboard normally cold starts without any required (just the upwards push on the ignition key) - which might be indicative of wrongly adjusted carbs I suppose. Engine still felt warm, but was simply turning over (first 7 attempts) until I pulled out the choke lever fully and then it caught - but needed full choke to keep it running for about a minute (which I would normally associate with a cold rather than a warm engine!).

Quote:

Originally Posted by spartacus

Fuel related: Did you switch fuel tanks and not open the vent fully? There is an internal fuel filter on your engine - check it's clean too..

I topped up the fuel tank with some fresh fuel - but the vent was left open over lunch. The internal fuel filter was flushed when I changed the diagphrams on the day before and looked clean.

Quote:

Originally Posted by spartacus

Electrical related: Might be worth renewing the HT leads. Check you're getting a spark to all cylinders first. Lastly, check the wiring for the stop switch. There's been a few threads regards loose wiring, faulty switch or the lanyard key not fitting properly.

- I haven't checked sparks to all cylinders - on the midweek list !
- I did notice that a slight sideways pressure on the lanyard seemed to cut out the engine at idle, but 30nm of running that day at various other throttle settings did not seem to affect it (including some quite lumpy bits of sea).

The Garmin fishfinder is shutting down due to a high voltage (16.5v typically) at anything other than idle - but I'm putting that down to other things until I can dig out my multimeter.

BumbleAbout · 25 July 2011, 22:30

Digging through the outboard manuals, I'm guessing that I should check the idle screw adjustment on all 3 carbs - hopefully tomorrow.

I tried to recreate the warm start problem a few weeks ago however at home rather than in the water but failed - maybe the cooling hose was too efficient !

ed_dash · 26 July 2011, 01:43

on my mariner, pushing the key in is the choke and lifting the level is just increasing the throttle.

So if you were pushing the key it could have been that you had flooded it but that should have cleared once it started.

BumbleAbout · 26 July 2011, 08:36

Hmmm - I tried a couple of starts initially without pushing up at all, but it has never ever started without pushing up.

It doesn't look as difficult as I thought to take the carbs apart, clean and then adjust the idle screws on all 3 carbs - so I will try that as a starting point - what could possibly go wrong

9D280 · 26 July 2011, 09:08

Quote:

Originally Posted by BumbleAbout

but when I tried to restart a couple of hours later

This is just my gut feel, but after 2 hrs or so I would not class that as warm.

Having said that, from the other stuff you have said My going in guess would be the HT system or the deadman wiring. I had a similar thing on the old Yam, and borrowed a Megger. Cold, both plugs were nice high insulation resistance. Once warmed up, one of them was a good way to shorted. Changed them and it was like a new engine.

You can get "spark meters" for a couple of quid from any good auto factor. Worth checking each HT lead too. They are a bit like a set of compasses with a plug top on one arm, an earth wire on the other & a scale between them. you basically open the gap until it stops sparking, if all is well that happens in the green sector of the scale. Sheer simplicity but very effectve tool.

jezza2011 · 26 July 2011, 11:07

Hi On my mariner 75 all I need do once its warmed up after the first inital start up is flick the key and its away. even if its been standing .
Only evern need the choke ( key push up/in ) is when we first start up or been standing for a ling time.
see if it start with just a flick of the starter. No choke or throttle..

BumbleAbout · 26 July 2011, 12:37

Thanks guys - that has certainly helped me narrow the work required down - so I suspect that I need to:
a) Clean and/or adjust the idle settings on the carbs so that the throttle increase lever is needed to cold start
b) Test the spark when warm which could indicate a plug and/or an HT lead issue

jyasaki · 26 July 2011, 16:36

Quote:

Originally Posted by 9D280

This is just my gut feel, but after 2 hrs or so I would not class that as warm.

I would. My current engine is injected and loaded with electronics and probably doesn't equate well, but my old Honda 40 was carbed.

My general procedure on the Honda: Cold start: Choke and a bit of throttle twist (no fast idle lever on the motor), 2 or 3 shots of the starter motor for about 5 seconds each. If the motor tried to fire, cut choke by about half, retry starter. If the motor fired, ran, and died, then choke to off and retry starter. If no fire, choke to off, throttle to full open, and crank for a bit to get air into the cylinders, then start over.

If the motor had been run in the past 4 hours or so, I'd give it a bit of throttle and hit the starter. Usually it would fire up and run as if it had just been shut down. If it didn't start in 2 tries, I'd give it just a bit of choke, and no throttle. Rarely did I have to go back to a cold start routine if it had been run earlier in the day (though weather plays with that statement as well.)

Gist of my post: It takes quite a while for a (or at least some) motor to return to dead cold condition.

jky

BumbleAbout · 26 July 2011, 21:40

First update:
I checked all of the carb idle settings this evening - the top two were spot on 1.5 turns to lightly close but the bottom one was way out (nearly 3 turns to close).

I adjusted that back to 1.5 turns; throttle advance lever to fully up; pressed choke in whilst turning the ignition key and it started second time (a first for this outboard).

I ran (with a hose) for about 5 minutes to warm up and then stopped for a couple of minutes. Starting warm without any choke but throttle advance on, worked every time I tried.

So it looks like a combination of user stupidity (used to Yamaha starting not Mariner) and an idle screw was all it needed

- so many thanks for all of the suggestions.

I'm going to get a spark meter and new plugs just in case however - another good suggestion !

BumbleAbout · 30 July 2011, 21:10

Second update:
New plugs today and then a blast across to the Folly Inn for lunch - all sorted !

Scrottocks · 17 August 2011, 11:56

I've had various starting/idling problems on a Johnson 70 (1994/5) that came with a RIB I purchased a couple of years ago. Gradually clearing out various gremlins and improving operation. Much had been neglected and mal-adjusted. Slow running was a somewhat fast and often hiccupped/died when throttling up away from idle.

Similar to you, the carb idle settings = the top two were spot on - 1.5 turns to lightly close but the bottom one was way IN (just 1/2 turn to close)." Still idling fast but ran sweet once on the go. Checked timing, idle mixture, idle adjustment, etc., etc. No luck.

Then I loosened each of the clamp bolts to the small arm which joins the three throttles together. Caramba!! Idle speed dropped to a sensible and correct speed. One of the carbs had been ever so slightly open and that was what had raised the idle speed.

Hope this helps

Arthur