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1991 8hp Carb issues

J

jwooden

New member
"Motor will not run when fuel

"Motor will not run when fuel line is "plugged in". I give it a couple pumps and and the fuel started dumping out the top of the carburetor. The motor acts like it's getting flooded. Is this a bad diaphragm or a float issue? The diaphragm in question is # 15/16/38 in the link below.
http://www.crowleymarine.com/mercury_parts/496/100.cfm

Thanks in advance for your expertise!
Also, any tips on where to get individual pieces instead of kits?"
 
check for a sticky float valve

check for a sticky float valve----often a cleaning is needed and NO parts required.
 
I just took apart the carb. Ev

I just took apart the carb. Everything seems clean and the float valve moves freely. It runs without the hose but immediately dies when I plug it in.
 
"Hi Jon,

could the float v

"Hi Jon,

could the float valve or its seating be somehow damaged, or worn? Not really an expert here, but sounds to my logic like the needle valve is not closing or seating properly if gas is oozing through.

Also, not sure if this might be relevant, but have you checked the proper level of the float? The top (well, actually bottom) of the float should be 1" (25 mm) above the carb casting when you turn the carb upside down and let the float rest on its hinge.

If required, you can adjust it by carefully bending the hinge to get the proper level. If in doubt, do check with a shop manual, since it's much easier to see in an illustration than to explain...
happy.gif


Re: the parts, I think most of them you can order individually from online or brick-and-mortar suppliers. However, with gaskets, the utility of this may be limited since you pretty much need to replace the whole set anyway if you take the carb apart. I've had some good luck just asking around at the local Merc dealer, they often seem to have left-over gaskets and partially used repair kits floating around, which you may be able to pick up at a bargain price.

Hope this helps!"
 
"BTW, if I'm not mistaken,

"BTW, if I'm not mistaken, I think the "15/16/38" gasket at the top of the unit (if that's the one you mean) is just a seal for routing fuel into some of the secondary passages of the carb (for the low speed mix, IIRC). In other words, it's not a functional diaphragm such as those in the fuel pump or primer assemblies."
 
"I'll check the float valv

"I'll check the float valve more closely.
I'm still baffled that the motor is running like it is. It's as if someone flipped a switch. One minute it's running purrrrfect, the next, I'm sweating my socks off trying to start this thing.
Thanks again."
 
I found the problem (with

I found the problem (with all your help of course). The seal around the float was bad and has filled up with fuel. The float valve was not able to close when the bowl was full. If I understand it correctly.
 
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