mercarb float setting

Skidaddle

Cadet
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Aug 28, 2011
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7
have overhauled a mercarb on a 3 7 l 4 cyl. now runs great for about 20 seconds! Thinking float?Any thoughts?
 

Don S

Honorary Moderator Emeritus
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Re: mercarb float setting

Do you have an engine serial number handy, model number, or a year, or carb number?
 

achris

More fish than mountain goat
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May 19, 2004
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27,468
Re: mercarb float setting

have overhauled a mercarb on a 3 7 l 4 cyl. now runs great for about 20 seconds! Thinking float?Any thoughts?

Answer Don's questions, but that sounds like a fuel pump problem with your 3 7 l 4 (whatever that is??? :D)....

Chris....
 

Skidaddle

Cadet
Joined
Aug 28, 2011
Messages
7
Re: mercarb float setting

Sorry to take so long to reply. Busy weekend. Even without a boat.
The 3.7 is 3.7 liter displacment 4 cyl. manufactured by merc.
Serial numbers on other hard drive. I will find that after work. It has the straight shaft accelerator pump.
I may have found the culpret. Somehow left the needle valve spring off.
I will be replacing that.
As far as fuel pump, haven't pressure tested the line but definitly getting fuel to carb inlet. Also tank venting checked,fuel filters replaced, fuel hoses replaced and fuel checked for water. Even picked up a fuel pump to replace existing but was the wrong one.
Still considering the pump but doesen't seem like any more fuel than its delivering is going to help. I am not sure about how to pressure test or if it is required.
Thanks for your help!
 

Skidaddle

Cadet
Joined
Aug 28, 2011
Messages
7
Re: mercarb float setting

Do you have an engine serial number handy, model number, or a year, or carb number?

Finally have the engine number. B459311
It has the Mercarb but I have to get the number off the tag. Had all this recorded until " the hard drive incident"
Have possibly zeroed in on a sticky float valve. Both original and carb kit replacement seem to stick.
If you give the carb a little tap, it will start and run beautifully for another 20-30 seconds. I'm thinking that's about when the bowl is dry and the tap is unsticking the valve and refilling the bowl and the valve re-sticking.
Any thoughts on this? At least I'm getting lots of practice removing and installing a carb.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: mercarb float setting

Both original and carb kit replacement seem to stick.
If you give the carb a little tap, it will start and run beautifully for another 20-30 seconds.

Have you been using any fuel additives lately? Have you checked the fuel filter in the pump? Might try an outboard tank with some new gas in it hooked directly the the fuel pump and see if it clears up the sticking.
 

Skidaddle

Cadet
Joined
Aug 28, 2011
Messages
7
Re: mercarb float setting

Thanks Don,
Yes, I will try rigging a boat tank if I can russle one up.
 
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