85 Mariner 50HP won't idle in water

[sgamer]

Past History: Bought used in '87, this motor worked great. The boat died in '90 and the motor sat in the garage until I bought a new boat in '96. It wouldn't idle and was hard to start so I brought it to a guy who rebuilt the carbs. It didn't run any better so I had a dealer check it out and he rebuilt the carbs. It didn't run any better so I brought it to another dealer who wanted to rebuild the carbs but I said no, fix the problem. That year on Lake of the Woods (huge lake) my motor ran like crap and I was worried I'd be stranded. I'm over a $1000 in "repairs" that have done nothing.<br /><br />Recent History: I've found that the motor runs almost as good as it ever has when hooked up to the hose and "earmuffs." Putting the lower unit in a garbage can full of water and it runs like crap. I'd be real interested if anyone can give me a good reason(s) why this is happening. I've stumped three mechanics with it today. Thanks in advance.

 

[JB]

Re: 85 Mariner 50HP won't idle in water

Evil spirits? Seriously, sgamer, let's look at what is different when it runs good: cooling water is forced through the system under pressure whether the water pump is working or not. You didn't mention anything about the water pump or overheating, but I think I would take a look in the lower end to see if anything there could be loading the engine down when water is not forced into the pump under pressure. This little voice keeps saying, "impeller is dragging", but it doesn't say why.<br /><br />Good luck, let me know what you find.<br />JB

 

[sgamer]

Re: 85 Mariner 50HP won't idle in water

Thanks for getting back to me so soon. The motor has always run well with the hose and "earmuffs" (what do you call these things?). Either way, the water pump was replaced (just for the heck of it) when I had some lower unit work done about a year ago. It made no difference.

 

[corm]

Re: 85 Mariner 50HP won't idle in water

Hi Sgamer,<br />Did they check out the stator and switch box<br />(powerpack). Those motors run fairly well ao 3 cylinders. Alos there is an oil recircilating tube running from the bottom bearing to the top bearing that cracks from age that will cause poor idle and take off on the starboard side under the switch box.<br />Is your problem at all speeds, low speed,ect.<br /><br />...have fun...corm<br />btw,L.o.t.W. is a great place.

 

[ODDD1]

Re: 85 Mariner 50HP won't idle in water

Corm's right...on the flushing ears these motors will start and idle well on 2 cylinders..you could have 1 or 2 cylinders down and not know it...running an engine on flushing ears is NOT the proper way to make any judgements about running quality..by the way,why are you letting off these so called 'mechanics'....professional people gaurantee their work..

 

[catfish]

Re: 85 Mariner 50HP won't idle in water

i was told that a 2 stroke has to have back pressure to run right. richen the up the idle some it might help it did on my merc.<br />also do it in the water you should see a improvement.

 

[JB]

Re: 85 Mariner 50HP won't idle in water

Gotta put in $.02 worth more. <br /><br />$.01: Corm's right. L.O.T.W. may be the best fishin' hole on the planet. I've certainly never been anywhere I was so reluctant to leave. It's not just the catchin', which is very good. It is an environment without peer.<br /><br />$.01: ODDD1's right about people who charge you for fixes that don't fix anything. Find a wrench with some professional pride.<br /><br />There. That's $.02 worth, and I feel better.<br /><br />Good luck.<br />JB

 

[sgamer]

Re: 85 Mariner 50HP won't idle in water

Thanks to all for the help. I'll check out the stator, switch box, oil tube and idle mixture and get back to you (it might be awhile). I have a Clymer manual that might help but I have my doubts. By the way, it's my fault that I haven't held the mechanics responsible since I don't get on the lake very often. By the time I do, it seems like old hat to bring it back in.<br /><br />Corm, the problem is primarily at idle/slow speed but I don't know that it performs like it once did. I get about 25mph on a 16'Smokercraft Kingtroller.<br /><br />Last fall at LOTW's, I had a mechanic take it out for a ride. He was leaning toward the internal gas tank (which has problems too) since the bulb wouldn't firm up. Then, when you revved it up it would idle for about a minute but squeezing the bulb didn't help much if at all. This year it won't even idle for a minute. I tested it with a new external tank and fuel line (I've become quite the little parts replacer) and the problem is the same but it has a firm bulb now. His other thought was that the reed valves were weak. Another mechanic thinks I should take the lower unit off and scrape the carbon out (Apparently since I haven't always used Mercury oil) and would charge me $450 to do so. This is the same outfit (Hallberg's) that did the second rebuilding of my carbs. Does any of this make any sense? I'm thinking about trading the thing in at one of the places that ripped me off but I'm sure the motor would just end up on some poor guys boat with the same problem. Those **** morels you know.