PLEASE HELP ME BEFORE I GO INSANE!!!!!! 1986 Mercury 75hp 4cylinder idle trouble

[geddron1976]

Re: PLEASE HELP ME BEFORE I GO INSANE!!!!!! 1986 Mercury 75hp 4cylinder idle trouble

Ok, i received the new shaft seals and installed the carbs back on to the engine. Followed the synch and link to the letter and guess what?
It still won't idle! I managed to tune it enough to get it to run smooth, but with the throttle valves completely closed, the idle speed was at 1900rpm?
Is there any way to bring the rpm's down? I have checked the whole setup out for air leaks and it's as airtight as a ducks ***.

i can only think that the timing is advanced too much, but bringing it down only seems to make the engine stall.

anyone got any fresh ideas as i am completely exhausted!

oh forgot to mention that it did run better with the seals and it doesn't leak fuel anymore. I also changed the fuel primer bulb just to be sure and it's all pressurizing ok now.

 

[geddron1976]

Re: PLEASE HELP ME BEFORE I GO INSANE!!!!!! 1986 Mercury 75hp 4cylinder idle trouble

Sorry its been a while! thanks to everyone that gave help and advice on the mercury 75. I finally got it going! turned out that the timing had moved (dont ask me how) it had gone so far out that all the linkages needed to be removed, refitted and then the link and sync done. It started and purred like a kitten..
The throttle was smooth and crisp and through the hole shot it never missed a beat. However, after having the feeling i felt when it died on me out at sea, i decided it was time to find an engine that i could put my trust in to again.
I picked up an ex RNLI owned 1996 evinrude 70 which had a new powerhead and gearbox in 2002 and has only done 75 hours since!
She runs like a dream and cost me less than the price i sold the mercury 75 for, so big smiles all round!

Thanks again for your help guys, without you i'd have probably consigned it to the scrap yard.

 

[mercuk]

Re: PLEASE HELP ME BEFORE I GO INSANE!!!!!! 1986 Mercury 75hp 4cylinder idle trouble

However, after having the feeling i felt when it died on me out at sea, i decided it was time to find an engine that i could put my trust in to again.
I picked up an ex RNLI owned 1996 evinrude 70 which had a new powerhead and gearbox in 2002 and has only done 75 hours since!
She runs like a dream and cost me less than the price i sold the mercury 75 for, so big smiles all round!

Thanks again for your help guys, without you i'd have probably consigned it to the scrap yard.

Shame you got rid of the Merc 75 buddy, I live near Southampton and probably could of helped you out with it. (I have exactly the same engine) Anyway good luck with the new Evinrude. Best regards.

 

[geddron1976]

Re: PLEASE HELP ME BEFORE I GO INSANE!!!!!! 1986 Mercury 75hp 4cylinder idle trouble

To be honest, the engine was great for 4 years. So much power and started on the button and cost me next to nothing over the time, but when it did let me down, it was quite a scary feeling. I don't get worried about anything usually but, the feeling of being 12 miles out to sea on a strong tide with no engine was probably the most uncomfortable i've ever felt. espescially when the back up engine wouldn't move the boat against the tide!
I managed to get towed back in fortunately! I then put it in to storage for a while and stripped it down, cleaned it all up and replaced all the parts i felt needed changing, serviced the carbs and then after the nightmare i started this thread about occurred... a trip to the marina and she was good as new again, but i still couldn't trust it if i were going out to sea again.
i feel much more confident just knowing that the evinrude has been very well looked after and after owning a 1980's evinrude 60 vro, i know how good the engine is.
being an ex lifeboat engine and having had a new powerhead and gearbox in 2002 and hardly being used since, i think that if looked after, this engine should be a good exchange. the evinrude cost me ?850 and the mercury sold for ?1200, so i even had enough change to get a new control box!
I hope the mercs new owner gets as much pleasure from her as i did and it serves him for a long time to come.. i'm quite pleased with the replacement and looking forward to buzzing around on the boat very soon...

Tight lines to all!

 

[mercurymang]

Re: PLEASE HELP ME BEFORE I GO INSANE!!!!!! 1986 Mercury 75hp 4cylinder idle trouble

To be honest, the engine was great for 4 years. So much power and started on the button and cost me next to nothing over the time, but when it did let me down, it was quite a scary feeling. I don't get worried about anything usually but, the feeling of being 12 miles out to sea on a strong tide with no engine was probably the most uncomfortable i've ever felt. espescially when the back up engine wouldn't move the boat against the tide!
I managed to get towed back in fortunately! I then put it in to storage for a while and stripped it down, cleaned it all up and replaced all the parts i felt needed changing, serviced the carbs and then after the nightmare i started this thread about occurred... a trip to the marina and she was good as new again, but i still couldn't trust it if i were going out to sea again.
i feel much more confident just knowing that the evinrude has been very well looked after and after owning a 1980's evinrude 60 vro, i know how good the engine is.
being an ex lifeboat engine and having had a new powerhead and gearbox in 2002 and hardly being used since, i think that if looked after, this engine should be a good exchange. the evinrude cost me ?850 and the mercury sold for ?1200, so i even had enough change to get a new control box!
I hope the mercs new owner gets as much pleasure from her as i did and it serves him for a long time to come.. i'm quite pleased with the replacement and looking forward to buzzing around on the boat very soon...

Tight lines to all!

I can't imagine being 12 miles out and losing an engine. Out in the middle of the lake is bad enough.

 

[RandallJD]

I have owned a 1986 75 Mercury and Mariners and when would have that problem I would check the resistance of the Stator. Must disconnect from switchbox/powerpack. Im looking for lower unit parts for my 1986 75hp Mercury.

 

[GA_Boater]

I have owned a 1986 75 Mercury and Mariners and when would have that problem I would check the resistance of the Stator. Must disconnect from switchbox/powerpack. Im looking for lower unit parts for my 1986 75hp Mercury.

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