mercury M90 carb parts questions

[stackz]

ok, engine is a 1990 mercury m90 2stroke engine. its always had this "dead spot" since I've owned it.

I'm thinking I've found the two problems.

1. I believe the fuel filter is on backwards lol. the arrow is pointing towards the fuel pump outlet and NOT towards the carb inlet as you can see in my picture (yes, I had to draw the arrow as it showed up VERY LIGHT in the pic lol).

2. the carb linkage is all cracked up and "slips" against itself so not all three carbs are opening together exactly.

anyone know what the black part is specifically called so I can order replacements?? I need two of them, they are both cracked from people apparently over tightening them...

also, I'm assuming the fuel filter being on backwards isnt helping much either with fuel flow?

 

[achris]

Re: mercury M90 carb parts questions

Replace the filter with a new one, pointing the right way ...

This drawing may help you... Pick the bits you need.

Chris.........

 

[stackz]

Re: mercury M90 carb parts questions

I'm going to assume according to that pic that the lower one which has no # on it shares the same part number as the upper one which is #19??

 

[achris]

Re: mercury M90 carb parts questions

I'm going to assume according to that pic that the lower one which has no # on it shares the same part number as the upper one which is #19??

Correct... If you look at the part listing in the QTY column you'll see that there is 2 on this engine.

 

[stackz]

Re: mercury M90 carb parts questions

cool deal, the little wave in the diagram is what threw me off and I already covered everything back up outside and the mosquitos are horrible after I took a shower and washed off all the bug spray haha.

for my own purposes tomorrow at work...WME is the carb designation.

gotta print up some stuff to take to the marine store to get parts lol. gaskets are all dry rotted.



edit: here's a question, there's a little port on the TOP of the carbs by the rich/lean adjustment where the top panel covers everything...this little hole has a threaded bung that looks like a carb jet but its wide open to the inside of the carb (hollow) its got me kinda weirded out. anyone know what this is and why its open like that?? is it some sort of idle open air bleed or what?

 

[achris]

Re: mercury M90 carb parts questions

Sounds like the bowl vent jet... Download the service manual HERE and have a look in the Fuel section.. Some good drawings you can check against... (File Password is <<ribforum>>)

Chris.....

 

[sschefer]

Re: mercury M90 carb parts questions

cool deal, the little wave in the diagram is what threw me off and I already covered everything back up outside and the mosquitos are horrible after I took a shower and washed off all the bug spray haha.

for my own purposes tomorrow at work...WME is the carb designation.

gotta print up some stuff to take to the marine store to get parts lol. gaskets are all dry rotted.



edit: here's a question, there's a little port on the TOP of the carbs by the rich/lean adjustment where the top panel covers everything...this little hole has a threaded bung that looks like a carb jet but its wide open to the inside of the carb (hollow) its got me kinda weirded out. anyone know what this is and why its open like that?? is it some sort of idle open air bleed or what?

Re your edit question... That's the way they are, no need to worry.

 

[stackz]

Re: mercury M90 carb parts questions

ok, I think I'm in a little pickle lol.

went by my local boat parts dealer and apparently they only had one of the throttle links and said they cant get anymore as they dont supply for mercury anymore, wtf?

they called around town for me and nobody else has any either. I looked up the part number on here and apparently iboats doesnt supply them either. anyone know where I can get one and the shipping wont kill me on a $3 part?

also, I got the carb gasket kits as well while I was there but they only came with one of #11 in the diagram. I managed to save three old ones from the previous setup and have them on the outer flange but I'd rather have new ones since I have new for all the other gaskets.

also, they had a fuel filter which crossed to my engine but when I went to swap it, it appears too small diameter hose. it looks to be 1/4" while my old one looks to be 5/16". I was able to get it tightened down but I'm not comfortable with any kind of fuel restriction inline to the carbs, just dont like it. that and I think I need to buy some new fuel line as well as my old hose coming from the fuel pump outlet is kinked a bit which could also be contributing to the dead spot problem.

anyone have anything to add? comment?

 

[achris]

Re: mercury M90 carb parts questions

Sounds like you're getting the run-arounds...

Try www.mercruiserparts.com for the engine parts you're looking for. I don't know what they are like on the freight...

As for the filter.. Yes it does come in 1/4" and 5/16". You really need to get the 1/4" out of your engine. The correct part number for the filter is 35-816296Q2.

Chris...........

 

[stackz]

Re: mercury M90 carb parts questions

.2lb weight through them. minimum shipping weight of 1lb @ 7.71 means thats a $10 plastic link lol.

wish I needed more parts to justify that. might look around on there as I'm sure there's more gaskets and such (spark plugs, etc) that I'll need lol.

might as well finish off the parts.

anyone have a diagram like the one posted above for the carb front cover?? I know its not really necessary but the carb cover gasket is torn badly and it cant be that much...

oh yeah, are there part numbers on the fuel lines? I know they are just regular fuel line but that is a SHARP turn so molded line would be nice to have if it actually is molded from the factory.

 

[achris]

Re: mercury M90 carb parts questions

Hi again,

Download the manual for your engine HERE and you'll have all the diagrams. Password for the file is <<ribforum>>

You can look up the part numbers at www.mercruiserparts.com by selecting the 'Search with Pictures' option... It then gives you selections to get to your engine. Gives you the part numbers and prices...

Chris...........

 

[stackz]

Re: mercury M90 carb parts questions

cool deal. looked up the diagrams and actually found a mercury dealer local to my work place that has everything in stock. yay me!