1971 9.5hp Johnson high speed fuel mix

[Voigt Kampff]

How do I adjust the high speed fuel mixture? My book offers little help. Is it the "high speed orifice" screw thing that is hidden behind the float compartment drain plug?

 

[ultra353]

Re: 1971 9.5hp Johnson high speed fuel mix

You don`t adj the high speed orifice, its a fixed jet. Yes the high speed orifice/jet is located behind the drain plug on the bottom front of your carb

 

[Voigt Kampff]

Re: 1971 9.5hp Johnson high speed fuel mix

A few more details.... Carb was rebuilt and has been cleaned and runs but I had a bad mechanic. It idels fine and runs when shifted into gear but runs bogged down. I have to pump the bulb every few seconds to feed it enough gas. If I do not pump gas it dies after several seconds but before it does die it revs up and picks up speed and runs awesome for half a second. That is what lead me to believe it is the high speed idle adjustment.

 

[Voigt Kampff]

So how do I adjust the high speed fuel mixture? My manuel pointed out how to on other models that actual have an adjustment knob or screw but I have neither

 

[kfa4303]

Re: 1971 9.5hp Johnson high speed fuel mix

HI Voight. You're describing the classic symptoms of a bad fuel pump. Your cab has a fixed high speed jet that is not and can not be adjusted. However, you should have a low speed needle that can be used to dial in the idle. Here's a link that can walk you through a basic carb set up.

http://forums.iboats.com/showthread.php?t=167352

 

[F_R]

Re: 1971 9.5hp Johnson high speed fuel mix

Your fuel pump isn't delivering enough fuel to the carburetor. But about the high speed jet: Only two things go wrong with one,
1. It is dirty (runs lean)
2. Some genius ran drills or wires through it and made it oversize (runs rich).

Well actually three:
3. Somebody put the wrong orifice plug (jet) in there.

 

[Voigt Kampff]

Has a new fuel pump and I have built two hoses to make sure I didn't have an air leak. so there is no way to adjust the high speed fuel mix? I have no problem with the idle mix but I don't have a knob of any type or screw that does high speed mix that I can find

 

[Voigt Kampff]

It just didn't make sense to me that I can force gas into it until it floods out but right when it uses up all the fuel in the carb it runs perfect. Seems like if it was the fuel pump why is it running bogged down even with me fluttering or pumping the bulb but runs perfect right when it has nearly used up all from the carb? And it seems to use a lot of gas for a 9.5. I'm just confused and frustrated from fighting with this thing for months

 

[Voigt Kampff]

Also I have a 69 I have been scavenging from for body parts and stuff and I have notices the two small circles or plugs on the side of the carbs are tapped in at a different depth and I can't find in the book what those are for. Any connection?

 

[ultra353]

Re: 1971 9.5hp Johnson high speed fuel mix

Those plugs are welch plugs, they cover ports and are removable so you can get to the ports to be cleaned. Once removed they are ruined and need to be replaced. Sure sounds like a fuel issue, take the fuel line off the pump that goes to your carb ( make sure carb is full first) put that line in a clear bottle and start motor . You should have steady pulses of fuel coming out. Also, maybe your "bad mechanic" didn`t set the float correctly.

 

[Voigt Kampff]

Cool thanks. I'll make sure it is all clean and make sure the float is right holding it vert and making sure it is parallel and make sure the fuel pump is working. Thanks yall