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4 hp won't idle

T

Tipster1947

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Mercury 1999 IE4L Model 100421 VK

Carb – KEIHIN F520C ML09

This engine was submerged in brackish water for two weeks after Hurricane Sandy. It started and ran afterwords, but we had other priorities. Then it wouldn't run at all. After cleaning carb it now starts readily and runs at medium and high speed but it does not idle well. I’ve flushed out every tiny opening I can find, but I was unable to remove the bronze nozzle which covers the access to what I believe is the man jet. It is corroded in place. Only a destructive will remove it.

Is there anything else that could be causing this problem?

Do I persist with this or just replace entire carb.

Thanks!
 
Spray it w/PB Blaster and let it set overnight. Use a long handled screwdriver that fills the slot and give it a jerk.
 
Thx guyjg. Already tried liq wrench, but can't hurt. Top of jet is already slightly damaged. Would dirty jet affect idle or might it be be something else not related to carb?
 
I actually have one of these, but afraid to use on little carb. Right now soaking in PB Blaster. Have you opinion as to whether this is why motor won't idle? It runs at higher speed fine.
 
It can contribute but may need to go back thru the idle circuits again w/a a fine strand of copper wire, Sea Foam Deep Creep spray and 100 PSI compressed air.
 
Impact hammer worked! :) nozzle is out. However small cylindrical device seem to be stuck. - part 2 on this diagram (click to enlarge) - I assume it has lots of tiny holes that could be cleaned. How is this supposed to come out? :confused:
Merc OB carb 5329.jpg
I am not really prepped for tearing down entire engine. I've torn apart weed wacker engins after they froze (too little oil in mix), but they seem pretty simple.

Water was brackish and immersion was limited to a few hours.
 
SeaFoam Deep Creep is a great product to use...cleans out crud right now. Spray some carb cleaner thru the opening. I wouldn't blow compressed air thru the hole. Just keep spray cleaner thru it.
 
I am running out of options. Sea foam and overnight soak still not effective. Engine does not seem to want to run a steady speed. It tends to accelerate but still won't idle. Float valve? Still clogged somewhere?
Diaphragm 6 seems pretty floppy, but I don't know how it's supposed to look.


Carb Diagram 1.jpgcarb rebuild kit.jpg
Carb rebuild kit costs about $80.00 and does not include jets. Whole new carb costs under $200.00. Time to replace or is there something else going on not related to carb?
 
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