Mariner 50hp 4 stroke tickover problem

Dobieman · 04 July 2010, 15:57

The tickover is a little unpredictable - sometimes it is fine, ticing over at just under 1000 rpm and going into gear lovely but sometimes the tickover rises to approx 1600 to 1800 revs,

I have cleaned out and balanced the carbs and put new plugs in.

I was thinking an air leak may cause these symptoms?

any ideas?

thanks

Nos4r2 · 04 July 2010, 17:14

When does it rise? Any particular time?

Dobieman · 04 July 2010, 17:46

No it was random, i was using the boat to potter around the non tidal thames 4 / 5 knots and 1800 / 2000 rpm and it was when slowing down and waiting for the locks ect ( which is pretty often... )
At some locks it was fine and some it was not.

May have been my imagination but when it was playing up when i lifted the cowling the revs would fall then when i put the cowling back on they would rise again..

Shaz · 04 July 2010, 18:47

Dunno if its relevant at all but my car has a similar problem, which is caused by a faulty throttle sensor, if your engine has such a thing could be something to look at.

Dobieman · 04 July 2010, 18:53

I dont think it has one as it has Carbs rather than EFI.

( Unless someone can tell me otherwise? )

Thanks for the suggestion.....

BogMonster · 04 July 2010, 19:49

Sounds like what my aux was doing when the carb was full of poo - are you sure you found all the jets? I didn't, the first time I took mine off...

outboardtech · 05 July 2010, 20:50

HOW have you balanced these UP ??? Have you set the bottom carb to 1000rpm and then vacuumed the others . ALSO what gauges are you using . SORRY im NOT being difficuilt here but I have had alot of issues with BAD GAUGES and gauges that DO not work properly . Also what are your mixture screw settings . I would really like to know the make of the gauges ?? Barry

outboardtech · 05 July 2010, 20:52

I think your issue is STILL carburation . did you get those small intermediate jets out ??

Mollers · 06 July 2010, 07:57

Quote:

Originally Posted by BogMonster

Sounds like what my aux was doing when the carb was full of poo -.

Sh*t in the carb?

Downhilldai · 06 July 2010, 16:08

Quote:

Originally Posted by Mollers

Sh*t in the carb?

Is that the problem, or the solution?

Mollers · 06 July 2010, 16:25

Quote:

Originally Posted by Downhilldai

Is that the problem, or the solution?

I just wondering how often it was required.

Nos4r2 · 06 July 2010, 17:40

Quote:

Originally Posted by Mollers

I just wondering how often it was required.

Are you having trouble balancing on the transom to do it then?

Dobieman · 06 July 2010, 18:05

Thanks for any replies......

Outboard tech - these are the guages i have :
http://www.motorcycle-superstore.com...ronizer---.jpg

Firstly i tested each guage on cylinder 4 to make sure they were all reading the same, then set the tickover to 1000 and matched cyl 3 to 4, re-set the tickover and matched cyl 2 to 3 and 4 ect until all carbs were reading the same at the 1000 rpm

I got all the large and small jets out of each carb except for 1 of the small ones which i cleaned and blew through as best i could.

I have not touched the Idle mixture screws at all, but my manual says they should be set to 1 turn out.