Mercury outboard problem- please help!

[halyardmonkey.]

Hiya all,

I have a little problem with an outboard that I could really do with some ideas about.

It's a 4hp outboard mercury two stroke that has some strange behavioral problems..... Will start easily from cold and will idle easily, however, once you put it into gear it will cut out unless you keep the revs up- If you have succeeded in motoring a little the engine will idle in gear usually but not always.

However the engine will cut out usually just off idle to around 1/4 throttle when in gear and struggle to pass through this faze into cleaner running..... If when you reduce the throttle the engine will cut out.....

The engine has on two occasions been into the drink... But has always been dragged out quickly and has worked afterwards....

Have checked the plug and it is fine, cleaned the carburetor but admitted could not get the jets out.... Perhaps this is a clue???? Have taken the head off to check the condition of the bore which seems fine...... The engine does have a slightly gravelly sound to it though.....

It may well have more than one problem.

So any ideas or thoughts would be great!!!!

 

[VicS]

I think I'd do a thorough carb clean. If there is a carb kit avaialble probably get that. ( there should be but you don't tell us serial number to check)

Any carb adjustments that might need tweaking?

Does applying a bit of choke help. If it does definitely go for the carb clean.

What was done to it after going in the drink? Salt water?

What age or serial number ?

 

[djh1962]

Hi
had same type of problem with my Mariner 4hp 2 stroke, cleaned carb and replaced petrol which cured it. Perhaps a bit of redex and a good thrash will clean jets. There was a real good American outboard forum site which is packed with usefull stuff too, sorry can't remember address.
Good luck.

 

[markdj]

Idling jet on the carb is probably gummed up a bit. At least you can run the engine - I'd spray in carb clean and leave it for the specified period of time, usually a few hours, and hopefully that should help.

 

[Dipper]

On a two stroke, it is always worth renewing the plug even if it looks like the fault is something else. Been there, done that.

If it turns out not to be the plug, you will have a spare.

 

[halyardmonkey.]

I think I'd do a thorough carb clean. If there is a carb kit avaialble probably get that. ( there should be but you don't tell us serial number to check)

Any carb adjustments that might need tweaking?

Does applying a bit of choke help. If it does definitely go for the carb clean.

What was done to it after going in the drink? Salt water?

What age or serial number ?

I'm afraid so....in the thames of all places........ It is a 1985 dt4- two stoke! Do you know any standard settings for air screws and such?

 

[VicS]

I cannot find any info on a an '85 4hp.

My fear is that it was not overhauled as thoroughly as it should have been after its dunkings.

A very good US forum site for outboards is http://forums.iboats.com/forumdisplay.php?f=4

 

[halyardmonkey.]

I cannot find any info on a an '85 4hp.

My fear is that it was not overhauled as thoroughly as it should have been after its dunkings.

A very good US forum site for outboards is http://forums.iboats.com/forumdisplay.php?f=4

Thanks for all your efforts,

Gave the carb and proper strip down today, flushed the fuel tank and fuel filters, new fuel, clean plug and eureka! Fixed! Will give it a run up the river tomorrow to make sure but was fine in the tank........

Thanks all!