Mercury problem....

[mmmouse]

went fishing with uncle joe yesterday, he has the same boat as me a v213c haines. his has a '92 model v6 carburetted 200hp merc...

at speed the motor runs fine, you'd never think the thing had a problem, but slow down, come off the plane and settle down to idle and thats where the problem starts.

the motor drops to a slow idle, almost stalls and then picks up revs above a fast idle then slows again to almost stall...surging i guess u could call it....but if you run at idle for more than a few minutes the motor will stop and needs priming before it will start again.

when its above 140 dgrees on the temp gauge it will idle sometimes, but not all times.

he had in at mercury last week, they seemed baffled and "serviced" the fuel pump (fuel pump was rebuilt 2yrs ago). yesterday showed it had fixed nothing and if anything it performed slightly worse than normal....any ideas???????

[D river]

Mate when its a fuel prob I start at the source. Pull out the tank the fuel lines(all of them) and both the filters. Clean all of these with metho and replace the filters with new 1's (1 under cowl will prob just need clean as it prob just a screen). Cut open your filter and have a look you'll be surprised what gets through the pumps. Fuel line is chea so if its old replace it. When putting it back together make sure every thing is secure and clamped properly unseen air leaks can be the cause of many probs. When all this is done, (maybe an hours work tops) its then down to the carbies or the spark, or maybe even the timing. If you need help from a shop I'd be taking it somewhere else now as the guys you took it too obviously dont know. Mobile guys are good cause if they not they dont make a living where shops get work no mater what as they have big signs out the front.

[markbxy]

you said it works better when the temperature is hot have u checked the thermostats in the heads could be running to cold at idle.

[propdinger]

if its working at speed but plays up at idle i would say crap in the carby or a air leak thats only bad enough to stop the flow at low idle. but my money would be idle jets are blocked

[FishHunter]

Check the primer bulb as they cause lots of issues

[neil_stessco]

Does it have electronic ignition like the black max's?

[Dignity]

Mate when its a fuel prob I start at the source. Pull out the tank the fuel lines(all of them) and both the filters. Clean all of these with metho and replace the filters with new 1's (1 under cowl will prob just need clean as it prob just a screen). Cut open your filter and have a look you'll be surprised what gets through the pumps. Fuel line is chea so if its old replace it. When putting it back together make sure every thing is secure and clamped properly unseen air leaks can be the cause of many probs. When all this is done, (maybe an hours work tops) its then down to the carbies or the spark, or maybe even the timing. If you need help from a shop I'd be taking it somewhere else now as the guys you took it too obviously dont know. Mobile guys are good cause if they not they dont make a living where shops get work no mater what as they have big signs out the front.

I used to use a shop mechanic (south side Brisbane) who seemed to be very cheap compared to others I had tried but always had similar issues. The bloke I now use (mobile and comes to the house) listened very carefully to all I had to say, asked me many questions and after he looked the motor over suggested much the same as D river, replaced all the fuel and oil lines and cut them apart for me to show me how they were breaking down internally. The crap in the carby was unbelievable and he could show me that the majority of it was from the fuel lines. Also there was a valve that was recommended by merc to be replaced some 6-7 years ago in the carby with a newer type and had never been done, made a huge difference to starting as the old one was like corrugated cardboard and just let fuel drop back into the tank after 5 mins of sitting.

Included in his service are the minor details that others may miss, such as he strips the foils and greases the bolts that hold it in place, takes off all the zinc anodes and buffs the mating surfaces back to make sure there is a good connection with the motor.

The amazing thing is that he was as cheap as the "shop" mechanic I had used yet solved all my probelms and I use him for both my boats now, I'd say "Hi" to Ken but he doesn't know how to use a computer only outboards.

[mmmouse]

thanks everyone for the input....d river all the fuel lines, filters, and bulb have been replaced and made no difference.... and neil yes it's electronic ignition...thermostats are new too!

fuel pump diaphragm was replaced

the merc guys tried to reset all specs but were not able to achieve this!!!! things like reset timing to 9degrees btdc but could only get 7 btdc?????

i think a full carby clean is in order, it probably hasn't had one in it's life so there could be plenty of gunk in there, and maybe renew the jets...

dignity, you could be onto something with that valve in the carby just wondering if the motor ur referring to is the same or similar??? v6 200 these have 3 carby's could a suspect valve in one cause the problem?? for the age of the motor is it possible for all 3 to be defective????i'm thinking yes!!

[neil_stessco]

The bottom carb will always be the dirty one as it's at the bottom. Very easy to work on the merc carbs just make sure they are balanced right or she'll want to stall all the time at take off.

[djfish71]

Some of these engines were fitted with a idler stabiliser, it is a black box & was mounted either above the carbs or on top of the block near the heads, provided a lot of idle issues. it can be disconnected easily