Mariner 75hp Carb help

[billnorfolk]

Originally Posted by steve-ribnet

Hi
I would just make sure that 3rd hose was clear - remove pipe from engine and pump first and blow through to remove fuel or oil residue from the pipe
Turning the engine over will clear excess fuel from crankcase if it has leaked in from this pulse line.
If you have the option to test the motor after rebuilding just the pump, it will give you an indication whether the problems did really arise due to pump problem, and what condition the carbs are in
Rebuilding carbs is quite straightforward- lots of posts on here about doing it. Just be thorough and meticulously clean - carb cleaner, compressed air and ideally ultrasonic cleaner too.

All the gaskets hear ,nearly the price of a new engine lol.Will run it up in the tub after pump rebuild see if its made a difference ,gasket sets for carbs ,plenty of carb cleaner ,and reed box gaskets hopping will be running ok after this.

[billnorfolk]

Originally Posted by office888

Just a heads up :

Debris can wear out your jets...high velocity fragments will slowly erode the needles and jets, effectively stepping up your jet sizes, causing running problems.

Few people realize how important a good 10 micron filter / separator really is. Better too much filtration than too little!

(I'm running a 2 micron + vac gauge on my ETEC)

Have often thought of a 8mm fuel filter in the tank lead ,after the bulb ,inline fuel filters are quite cheap maybe replace twice a year ,any thoughts on that.

[steve-ribnet]

Please tell me you have got the full pump rebuild kit including the gaskets, diaphragms, non- return valve flaps and stems

[steve-ribnet]

Originally Posted by billnorfolk

Have often thought of a 8mm fuel filter in the tank lead ,after the bulb ,inline fuel filters are quite cheap maybe replace twice a year ,any thoughts on that.

Your main engine water separating fuel filter should be sufficient. The common setup is to have one of these bolted to the transom by the engine
Quicksilver Fuel Filter / Water Separating Kit - Mercury - Mariner - Outboard | eBay

A little off-topic now:
You can put a quick release fitting on the INLET side of one these blocks, then a matching fitting on your inboard tank line (if you have one) and also on your portable backup tank (if you carry one). This way, even if you switch from main tank to portable reserve tank, it will go through the filter.

I have a fuel flow meter on my fuel line right as it exits the inboard tank. This requires a filter before it in the fuel line, for which I use a small inline filter . This is much coarser than the main filter - 20 micron - compared with the 10 micron main filter.

I think these small filters are a little fragile just to have flapping in the breeze (you can get plastic or glass ones), but I have clamped this one securely to a bulkhead inside the console by the inboard tank.

So long as you have the means to bypass/replace these filters at sea in case they become choked...

[billnorfolk]

Originally Posted by steve-ribnet

Please tell me you have got the full pump rebuild kit including the gaskets, diaphragms, non- return valve flaps and stems

Yes Steve everything there its A42909A 4 Diaphragm kit ,inc gaskets springs ,valve flaps and stems.

[billnorfolk]

Originally Posted by steve-ribnet

Your main engine water separating fuel filter should be sufficient. The common setup is to have one of these bolted to the transom by the engine
Quicksilver Fuel Filter / Water Separating Kit - Mercury - Mariner - Outboard | eBay

A little off-topic now:
You can put a quick release fitting on the INLET side of one these blocks, then a matching fitting on your inboard tank line (if you have one) and also on your portable backup tank (if you carry one). This way, even if you switch from main tank to portable reserve tank, it will go through the filter.

I have a fuel flow meter on my fuel line right as it exits the inboard tank. This requires a filter before it in the fuel line, for which I use a small inline filter . This is much coarser than the main filter - 20 micron - compared with the 10 micron main filter.

I think these small filters are a little fragile just to have flapping in the breeze (you can get plastic or glass ones), but I have clamped this one securely to a bulkhead inside the console by the inboard tank.

So long as you have the means to bypass/replace these filters at sea in case they become choked...

We don't have a water separator filter only the in line filter on the engine ,we need to look at something like that as no filter before fuel pump probably some of my problem .Was thinking before you posted that ,maybe an inline filter in the fuel line from tank that could be changed at sea if need be.

[office888]

Originally Posted by billnorfolk

Have often thought of a 8mm fuel filter in the tank lead ,after the bulb ,inline fuel filters are quite cheap maybe replace twice a year ,any thoughts on that.

Inline fuel filters are typically 250 micron, or 100 micron...they only filter out HUGE debris.

Fine grit is the worrisome part. Over time, it acts like a mini-sandblaster, eroding any soft metal orifices, and causing premature ring wear.

I would HIGHLY recommend installing a spin-on 10 micron filter / separator. You can get them as a package for less than 50 quid. They're easy to change in the field too if you carry a spare... it goes on like a car oil filter. Just make sure you have some filter pliers handy.

What Steve linked is perfect. You'll need to add some 1/4 NPT barbs.

As an added bonus, it is also a water separator. I know you guys across the pond don't have ethanol-free fuel, which sucks, since ethanol absorbs water out of the air. Inline filters don't remove water.

[billnorfolk]

Originally Posted by office888

Inline fuel filters are typically 250 micron, or 100 micron...they only filter out HUGE debris.

Fine grit is the worrisome part. Over time, it acts like a mini-sandblaster, eroding any soft metal orifices, and causing premature ring wear.

I would HIGHLY recommend installing a spin-on 10 micron filter / separator. You can get them as a package for less than 50 quid. They're easy to change in the field too if you carry a spare... it goes on like a car oil filter. Just make sure you have some filter pliers handy.

What Steve linked is perfect. You'll need to add some 1/4 NPT barbs.

As an added bonus, it is also a water separator. I know you guys across the pond don't have ethanol-free fuel, which sucks, since ethanol absorbs water out of the air. Inline filters don't remove water.

I take it by barbs you mean for connecting the fuel lines to ,do they need to be in brass or plastic ,and can they be bought on ebay .Thanks Bill

[office888]

Originally Posted by billnorfolk

I take it by barbs you mean for connecting the fuel lines to ,do they need to be in brass or plastic ,and can they be bought on ebay .Thanks Bill

They're typically brass or aluminum.

The longer ones are better so you can make your fuel lines NMMA / ABYC approved by putting their specified two clamps on them. It is also recommend to use a liquid paste sealant on the threads instead of teflon tape, which can potentially put debris in to the fuel...plus, teflon tape is not technically compatible with gasoline.

You can definitely ebay them.

You'll need a barb that is probably 5/16 inch with 1/4 NPT male thread on it, since it sounds like you're running an 8mm fuel line? 5/16 in = 7.9mm...close enough.

[office888]

Originally Posted by office888

What Steve linked is perfect. You'll need to add some 1/4 NPT barbs.

Ignore this!

Made a mistake...these filters take a 3/8 NPT male, not 1/4.

[billnorfolk]

Ok got the right barbs ,now is it better to fit b between fuel tank and primer bulb or between primer bulb and engine .Ordered filter yesterday from a company in Douglas I.O.M arrived today can't fault that service .

[billnorfolk]

Had a morning working on the engine ,got in line fuel pump in place ,fitted onboard fuel pump kit and ran engine as suggested ,ran sweet for about 10 mins and then nearly died and picked up again ,as it was getting warmer it was getting worse though not cutting out .Removed carbs all seemed ok clean and working apart from the top one noticed it had beads of water in it ,but cleaned them and put new gaskets in place .Turned our attention then to the reeds ,all looked as they should apart from top one had beads of water inside cleaned them all .Now wondering if i have a head gasket problem or worse ,worrying thing is 2 or 3 of the head bolts look as if they aint going to move ,any ideas would be most grateful .

[Festinghouse]

if this is the 3cylinder 2stroke then there is no head gasket as the enginge has what is called a 'blind bore' where you cant get to the top of the piston except via the spark plug hole. if water is leaking in somewhere then i would maybe take off the big side plate which allows access to the exhaust and water galleries

[billnorfolk]

Originally Posted by Festinghouse

if this is the 3cylinder 2stroke then there is no head gasket as the enginge has what is called a 'blind bore' where you cant get to the top of the piston except via the spark plug hole. if water is leaking in somewhere then i would maybe take off the big side plate which allows access to the exhaust and water galleries

Yes it is a 3 cylinder 2stroke ,ok we thought that all the bolts on the back of the head held the head on ,glad we didn't start taking them out .Standing looking at the back of the engine where the plugs are you mean the side plate to the left hand side .The engine is a 1988 vintage ,clamshell hood.

[Festinghouse]

yes thats the one, its possible that water is getting through one of the gaskets there

[billnorfolk]

Thanks for the reply the front cover with the spark plugs fitted, could water get into the top cylinder from the thermostat ?

As the top cylinder is the only one which has signs of water?

[Festinghouse]

this is a 4 cylinder, but looks identical to the three as far as what lies under the rear cover plate. as you can see there is no way in to the cylinders at this point, the thermostat pokes into the water that surrounds the cylinders

[billnorfolk]

Thanks for helpful replies will have the side cover off tomorrow see what we find under there ,will keep you posted. Is that a salt build up ?looks nasty.

[billnorfolk]

Well put new gasket on the front head plate,gaskets on water and exhaust housing on left hand side ,carbs cleaned , reeds cleaned all new gaskets fitted .Fuel pump rebuilt ,new fuel pipes ,external filter fitted ,canister spin off type. Engine started first time and apart from initial hesitation ran quite well in tank .Ran it full throttle and tick over for about 30 mins no issues .Now can anyone advise me about carb and timing setting up ,seems quite a lot of slack in remote throttle control ,can open it about a third before throttle starts to open ,would like to try to get it set up before we hit the water again . There is a mention of a spark gap tester ,what is one of these. Thanks Bill