merc 454 fires but wont run

2kjs

Cadet
Joined
Apr 15, 2007
Messages
17
Hello all, having problems with a 1980 merc 454 (330)hp at end of last season engine quit on me (at about 1500 rpm) and couldnt get to refire. i was already having issue with rochester carb draining out if it sat at dock to long so givin the age etc.. replaced with new carb this spring but still no luck. As long as your turning key engine fires and is attempting to run as soon as you let off key thats it nothing. I dont think its a fuel issue carb is spraying gas, fuel pump and line have all been replaced prior to this issue. As for the igniton with cap off points are sparking while turning over and you cant turn rotor by hand so i dont think i sheared the pin on the distrib gear or anything. Is it possible distributor isnt advancing ? it is the original. Thanks in advance for your help !
 

ENSIGN

Lieutenant Junior Grade
Joined
Jun 21, 2009
Messages
1,179
Re: merc 454 fires but wont run

You may have a bad key or lanyard switch,connect a jumper between the battery pos. terminal and the coil pos. terminal [purple wire] and see if it will start.
 

chargerboy

Petty Officer 1st Class
Joined
Apr 28, 2010
Messages
362
Re: merc 454 fires but wont run

What's the compression of your cylinders like?
 

2kjs

Cadet
Joined
Apr 15, 2007
Messages
17
Re: merc 454 fires but wont run

thanks for the responses going to try to get down to the boat tomorrow after work and see what happens hopefully its this simple, haven't checked compression yet guess that will be next step if this doesnt pan out
 

buzzm19

Petty Officer 2nd Class
Joined
Dec 14, 2009
Messages
152
Re: merc 454 fires but wont run

I'm not sure on your electrical problem, but on your carb and fuel leaking down the common area is if you take the carb off and look at the bottom in the front you will see four lead seals and that is where your gas leak down is. It may not happen on a new carb but if it does and me I would do it anyway. It is recomended that you clean them and coat with jb weld to seal the leak from the carb bowls. Buz
 

2kjs

Cadet
Joined
Apr 15, 2007
Messages
17
Re: merc 454 fires but wont run

Well you guys nailed it, no power at coil with key in run position ran jumper from battery to coil and fired right up and ran good now just need to trackdown whether its bad switch, wire or both. Thanks so much
 
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