1987 Mercury 115 hp inline 6 carbs

mcqfamily

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Apr 30, 2012
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I have a 1987 Procraft that was given to me that will not stay running. The person that gave me the boat said 2 different marinas said that 2 of the carbs had stripped threads inside the carbs and that they could not be repaired correctly. The last shop to work on it had it running great but tolds the owner it would not last. on the 3rd trip out it started running rough and then would not stay cranked. I was hoping to find some used carbs to rebuild and replace at least 2 if not all 3.
Any body got any?
 

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,657
Best to buy a set if at all possible. Different carbs, different years, etc.
 

mcqfamily

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Apr 30, 2012
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I plan on picking up the boat this weekend. I was told that when the carbs begin to act up, that when it's in netural and idleing, it will go dead as soon as you put it in gear. You can increase the rpms and slam it in gear and it will go. Then in a few more trips it will not even idle. I'm hoping it's the air/fuel mixture adjustment on the carbs because I think I can put in the helicoil in without taking them off. If it's the high speed jet or low speed jet then I'd have to take them off and find out which one it is. If you had to guess which one it is, what would it be?
 

wired247

Lieutenant Commander
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Oct 8, 2011
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1,557
I wouldnt guess. I'd pull them apart , clean everything and repair any stripped threads and put them back together. I truly fail to see how stripped threads in anything will result in a carburetor running differently from one trip to the next unless the idle screws are backing out. Inline carbs aren't a lot of fun to adjust as they require a crazy rich idle to transition into the mains but clogged passages will make the carb impossible to tune. Low compression makes them hard to get to run right as do worn out labyrinth reed seals ( worst idea ever ), leaky water/exhaust gaskets, timing sequence adjustment etc . Hard motors to love.
 

mcqfamily

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Apr 30, 2012
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Thanks wired247. I just had a lazy streak hit me when I asked for the easy fix. This has really been a puzzle to the previous owner. I really want to fix it for him (really good friend) as he's tired of spending money on it with only temporary results. The boat will run 55+ on a 17' Procraft for a few trips and then starts a slow death until it won't idle anymore. He had all the fuel hoses replaced, pump bulp and a new fuel pump put on it.
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,044
Do some trouble shooting and find the real problems.------Waterpump ?----Lower crankshaft seal ?------plugged exhaust ?-----Tried running with a different portable fuel tank ?
 
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