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Have 1985 75hp mercury outboard runs then dies. put in new tanks and fuel line starts hard runs then shuts down pump ball a litle will keep running.

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Posted on Jan 02, 2017

  • 257 Answers

SOURCE: 1991 Johnsoon 90 HP outboard hard to start, floods after stop

Hi, You did a good job of assessing the problem. It sounds like the float valve in the carb is the likely problem. This would overfill the carb when sitting, flooding the engine and the pressure in the bulb pump would go down as the fuel leaked out. Float valve should be investigated and that should Fixya!

Posted on Mar 13, 2009

  • 52 Answers

SOURCE: 1974 60hp johnson outboard won't run on full throttle.

Carbs probably need to be cleaned and re-built. Common problem in outboards that havent been run in a while

Posted on Apr 13, 2009

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SOURCE: 9.8 hp mercury outboard shutting off in low idle speed.

My problem ended up being the spring on the reed valve being weak.But at the same time and while I had already had my carb broke down I took a can of carb cleaner to it and cleaned it. In order to replace the spring on reed valve you will have to buy a new one, but don't worry I only payed about $6.00 for mine. You may also look into replacing your primer bulb if you haven't already because may allowing air to build up in your gas line while you are basically idiling.Once you get the carb straightened out you may have to reajust it again. If I might be able to help you again you may contact me at

Posted on Jun 16, 2009

  • 636 Answers

SOURCE: I have a 1984 35 hp Mercury outboard that will

Have you checked the CDI module for a cracked wire or rubbed wire yet?

Posted on Jul 26, 2009

  • 57 Answers

SOURCE: Downloadable free repair manual

i searched for a site myself but had to eventually buy a Mercury service manual that covers 75 hp up to 150hp-has all engines specs maintenance and repair procedures-cost around $70 but invaluable

Posted on Sep 15, 2009

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I have a 1978 merc 85 hp outboard with a bad pump i purchased a used one that works mine has 4 hoses

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Dec 01, 2015 | Boating

1 Answer

Mercury outboard problems

the primer going flat indicates that the fuel is getting a vacuum in the system
the most obvious place is the vent in the fuel tank cap not being unscrewed to allow air in as the fuel is being used or that vent hole is blocked or rusted up
if by chance you have being using E fuel, it is now known that ethanol attracts water and separates from the fuel
that water attraction rusts tanks , corrodes alloy parts and destroys rubber hoses
it is especially not recommended for use on marine vessels and outboard motors
so the problem could be a stack of rust in the tank blocking off the inlet line

Mar 26, 2017 | Boating

1 Answer

I have a 20 hp mecury jet outboard motor that runs fine out of water but as soon as you put it in the water it'll run for a few seconds and then die and will not run again. It will soind like it&#

the rubber components of the fuel system from the tank, primer bulb hoses , fuel pump all deteriorate internally and the small rubber failings get to the carby and block all of the run circuits
experience says take it to a mercury service center and have the carby/s professionally overhauled as doing ti at home generally misses the important bits
never use e-mix fuels as the ethanol attracts water and the combination rots metal bits and hoses

Apr 25, 2017 | Boating

1 Answer

Any help with mercury outboard motor

Replace the fuel line from tank to bulb and from bulb to engine. The old type lined tube gets damaged by the ethanol content in pump fuel. Buy non ethanol fuel if you can. The lining come away from the walls of the tube and blocks the flow. You can force it with the bulb, but the fuel pump is not strong enough to open up the lining. Your problem is becoming a common occurrence. The worst stuff is the grey tube apparently.

The other obvious thing is to make sure the vent is open on the tank and working, but engines will normally run for a few minutes unless you have a metal tank.

Take a look at these images, then click on the 'All' tab to get ethanol resistant fuel line.

ethanol resistant marine fuel line Google Search

Jun 17, 2017 | Garden

1 Answer

Got a 92 model 175 outboard and the other day the revs just started dying down and it would stall sometimes. It would start and go again and found if we pumped fuel it would run bit better. Eventually it...

sounds like the pump ball check valve is bad or reversed -- check direction arrow. if the pump ball is bad - replace it with a new one. ( this could also be a fuel pick up tube issue -- empty the tank and check to make sure the pick up tube is still connected ).


Jan 05, 2011 | Yamaha Boating

1 Answer

Fuel problem

fuel pump sound like a good place to start it may not be getting enough pressure to the fuel thus not sending enough of it at a time to explain why it runs good sometime i think it is primeing and filling the lines once it shuts off and so for a litle while it has enough gas but one you use the gas that was ready in the line it can't get enough to run correctly. have it tested.

Aug 19, 2008 | 2000 Chevrolet Impala

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