1994 40HP Mercury have trouble starting

Iuse2fish

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Oct 27, 2004
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3
I have a 1994 Mercury 40HP outboard that just won't start easily when it's cold. Once I get it started it's fine until it cools down again. Then I have to reprime and rechoke and then it finally starts. I put new plugs in and they don't help. I just winterized the engine and when I pulled the plugs, 3 out of 4 were dirty. The forth plug looked brand new. The plugs have only been in since late June. Any suggestions?
 

JB

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Mar 25, 2001
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45,907
Re: 1994 40HP Mercury have trouble starting

Howdy, luse2fish.<br /><br />Welcome to iboats. :) <br /><br />This is the Non-repair Forum. You need to be in the Mercury Troubles Forum.<br /><br />I will move this for you.<br /><br />Good luck. :)
 

WillyBWright

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Dec 29, 2003
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8,200
Re: 1994 40HP Mercury have trouble starting

The clean sparkplug isn't firing. 3 possibilities. Bad coil, bad sparkplug, bad switchbox. Unfortunately the bad switchbox is the most likely. It might be worth having a dealer check it out. You probably don't have the meter to test the switchbox. Diagnostic time and repair time should total around an hour of labor. The switchbox is rather expensive. That's why you want it checked before you just up and replace it. Being an electronic component, it isn't returnable if your old one is good afterall.
 

Laddies

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Sep 10, 2004
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12,218
Re: 1994 40HP Mercury have trouble starting

Your engine is lean ck. the low speed carb adjustment
 

WillyBWright

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Re: 1994 40HP Mercury have trouble starting

I gotta disagree with you laddie. If the motor was starving that bad for gas, the motor would've locked-up by now. Even a lean carb would fire sometimes leaving some deposits on the sparkplug. It would have to be completely dry and that would roach the two cylinders it was feeding, not just one. But it does bring up the fourth and ugliest possibility that it's not getting gas due to no compression.
 

Iuse2fish

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Oct 27, 2004
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Re: 1994 40HP Mercury have trouble starting

Thanks for the advice I will break down and bring the motor in to be checked out by a professional.<br /><br />Bob
 

Moody Blue

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Joined
May 24, 2004
Messages
3,136
Re: 1994 40HP Mercury have trouble starting

I have a 93 40HP and it craves lots of gas to get it going once the temps drop below 60F. I will push the key in 3-4 times (enrichment solenoid)then hold it in while cranking. Fires right up every time. Even if I shut it down for 15-20 minutes I will have to re-choke to get it going again. As long as I give it lots of gas it fires up right away everytime.
 
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