1972 Mercury 800 beginning to be a pain

Gomer50

Chief Petty Officer
Joined
Sep 5, 2009
Messages
507
I have a 1972 Mecury 800 thunderbolt serial Nr.3192883.Well where do I start,It ran half way decent when I bought it seems that at one time its been rebuilt no info from previous owner.So I put new plugs in it,new plug wires new carb floats old ones were shot,new rectifier,new rebuilt fuel pump.Now it doesnt want to run.Has spark,but I dont think its getting fuel.I can pump the bulb until its rock hard and it tries to run but then goes back to just cranking.These carbs have alittle hole on top (side)of the float bowl and when I used to pump the bulb gas would come out.Not anymore.Gas does however come out of the front of the carbs.I have also noticed that when I hook up a timing light to 1,2,3,4 cylinder it doesnt seem like cosistant spark.Any help would be great.I can tear my truck apart and put it back together in my sleep but this thing is really getting to me.Compres. is good
Nr.1=120
Nr.2=130
Nr.3=130
Nr.4=130
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: 1972 Mercury 800 beginning to be a pain

Go to the Engine FAQs Forum, Gomer. Do "Outboard won't start".

Let us know what you find.
 

Gomer50

Chief Petty Officer
Joined
Sep 5, 2009
Messages
507
Re: 1972 Mercury 800 beginning to be a pain

I rebuilt the carbs and it runs once again,but I dont understand I also purchased NGK BUHW(1) Spark plugs and it doesnt like them at all.Will start but dies shortly afterwards.I put the old autolite plugs back in and it runs like a champ??? Any Suggestions......
 
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