Compression

[Nordin]

Your pump is a Mercury style and I am not so familier with that so I can be wrong, but are you pointing with your finger at the plate fuelpump partnumber 987752?
The one with the elbow?
If it is ,where is the hose from the elbow connected to?
I am thinking as you have two diapraghms in the pump it has a reinforced function using pulses from two cylinders to increase the flow.

 

[waterboy84]

You know i think you are exactly right. Imma post a couple of pics for you to see. Would make it alittle easier.

 

[waterboy84]

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[waterboy84]

Nordin. I posted 2 pics. One pic is just of the fuel diapham the i put fuel diaphram on and connected the only other hose witch does go down to the 4th cylinder.
And yes the part i was pointing at is the back of the fuel diaphram. The side that sits against the motor block

 

[Nordin]

The hole should be there, otherwise the pump will not work.
It is for the pulses from the cylinder to make the diaphragm go in and out.

 

[jerryjerry05]

The diaphragms are usable.
​But stretched farther than I like.
They will work. BUT?? Not as efficient as one with better diaphragms.
But I'd change them. Only about $20 for the rebuild kit.

 

[waterboy84]

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[waterboy84]

Ok so i got this picture posted above. Im trying to figure out what that plastic screw is for. The plastic screw my finger is pointing at.
This screw sits on the top of the carburetor. Been trying to research and research and cant find anything about this screw. Could someone with knowledge explain to me what the purpose of this plastic screw is for
Thanks for the info.

 

[waterboy84]

Jerryjerry. I have ordered a new diaphram kit and so im just waiting now for it to be shipped. I ordered it off ebay however i love ebay. Prices are so cheap.
At first i went to a boat shop called old salt marine and i could not believe they dont stock those kits. And this is a popular boat shop here in lakeland.
However they stock almost all mercury force parts but unbelievable they dont stock the fuel diaphram rebuild kit.
Anyways ording it off ebay was only $10 and then the few days to recieve it.
Im really hoping this fuel diaphram rebuild will improve performance of my motor if not then time to rebuild carbs. Ugh

 

[jerryjerry05]

The dreaded white plastic screw: OH NOOOO
​It's just a screw/plug covering the air/fuel jet.
Remove it and the jet can be seen in the hole.

 

[tommarvin]

Do not fear cleaning/rebuilding the carbs,just think how easy it will be the next time.
Carb cleaner and compressed air blow all openings clean adjust the float ,put it back together.
You-tube has great videos on carb cleaning.
On second thought,clean your carbs while your waiting for your fuel pump diaphragm.

 

[jerryjerry05]

Usually just cleaning the carb is all that's needed.
​Don't adjust the float unless it been changed.
A running motor all of a sudden the floats go out of adjustment.No
​Put it back together and go for a ride.
Don't do any unnecessary work until the right prop is on.

 

[waterboy84]

Jerry and tom thanks for the info. About the carbs. I have cleaned them already.
But no improvement.
I did ajust floats a bit due to fuel would leak out the throat and come out a little vent hole on side of the ccar when pumping primer blub.
It was the bottom carb that would leak so i adjusted float and bottom carb stopped leaking and top one started to leak so i adjusted the top carb the same as bottom and now it doesnt leak. Primer blub gets hard and stays hard and carbs do not leak.
However that was a issues i had a few months ago.
My issue i have now that im trying to figure out is the high crazy rpms when put into neutral. If i run the boat at low rpms and i put it in neutral the idle is fine.
But when i run boat at wot and cdrop back to idle then into neutral rpms raise and bounce around alittle.
However i did notice that if i ran my boat at wot and slowly drop throttle to idle then let it run in idle for about a minute then shift to neutral it will idle nice. No high rpms and no bounceing around.
Plus when this happens. The rpms will raise up and bounce around there will also be a wired sound co.ing from motor. I would discrib the sound a knocking noise. Last time i was in the water when it did this it sounded like the sound was coming from the lower unit.
I have inspected lower unit. Prop is tight. I changed the oil w days ago. Oil looked good. No water no discoloring in the oil. Drain plug had a small amount of metal shaving.
Like i said. If im running boat at wot at drop back to idle then into neutral that crazy sound i hear and rpms raise and bounce. But if i run it at wot and idle down and let it run in idle for about a minute then shift to neutral. It idles perfect.
Also. When i run boat at wot and slow down the back of the boat and motor gets hit by the waves i created. And i noticed when this happens is when the rpms raise and bounce and ill hear that noise i explained.
Is it ok if those 3 exhaust port holes get submerged.