Carburetor Leak

[kaylix]

I couldn't get the boat restarted after a pee stop. Squeezing the primer bulb caused a leak.
SO - after a tow back to the dock and further inspection at home. The fuel inlet hose on the first carb was no longer attached properly.
I fixed that and started putting everything back together. Then stopped and double checked squeezing the primer bulb, now I have fuel leaking out of the second carb.

It's coming from the air/fuel chamber.
Also, any ideas what #6 High speed Fuel Jet Access Plug does?

 

[Blkrvrbart]

My guess would be a stuck float needle. That would be my first place to look.

 

[mrcid]

Yep, was going to say the same. Might be time for a carb rebuild.

 

[kaylix]

I got the leak stopped by hitting the second carb with a soft mallet. That fixed it and I ran the engine for about 20 min.
Today I tried priming and fuel started leaking again. So I tried the tapping method the left side and then the right side... And now I have a broken throttle linkage.
Something doesn't want me boating today!!

 

[mrcid]

Float needle is sticking. Time to do a carb rebuild/cleanup.

 

[kaylix]

I ordered a single carb rebuild kit, $110 buck a carb isn't cheap. Maybe I'll do the other two over the Winter.

 

[kaylix]

Out of curiosity and to make sure I'm fixing the correct carb. How would fluid from the bowl of the carb get up into the air intake to then leak out? Does squeezing the primer bulb pressurize all the carbs and if something is stuck that's where it would leak?
The carb looked pretty good when I dismantled it.

 

[mrcid]

If the float needle is leaking, pressuring the bulb would push fuel past the malfunctioning needle, into the bowl, overfilling the bowl. Which could then lead to fuel being pushed into the intake.

A good way to test if you needle valves are working is to run a pressure test on your fuel system.

In the "closed" position. That needle valve should shut off any fuel coming into the bowl.

From looking at the pics provided. It looks like the needle seat is also replaceable. Many carbs do not have replaceable needle seats.

Here's is a video on pressure testing:

It's not the same carb, but the process is the same for any carb.

 

[kaylix]

I got the unit back together and all is good. I got a little confused on a few of the pieces. And It is idling much faster than before (just adjusted the primary pick-up screw to lower the idle, i guess that's ok??)
The Screw on #11 was all the way in before the rebuild. But screwing it all the way caused the throttle plate to remain open, so I only screwed it in to the point where it opens and closes freely.


Also, I don't have the rod highlighted in yellow and there isn't a connection point anyway. Is that a Problem??

 

[mrcid]

Not really sure about the missing linkage in yellow, but it looks like some type of throttle linkage to me.

What size engine is this?

 

[kaylix]

Its a 175

 

[Stomp10]

@kaylix Ok, the missing linkage is for your oil pump. Someone has done an oil injection removal on your engine so, you need to premix your gas at 50:1 now.

You will also want to adjust throttle plate closure at the idle stop screw Item A in the picture....:


Also you need a manual. You can have access to one here:

Boatinfo - Mercury Service Manual for 175xr SportJet

boatinfo.no

If you are able reset the adjustment you made before to where it was and then make your change at the Idle Stop screw.
You want to be careful with your adjustments as you can mess up the timing by just making random adjustments at the throttle lever.

Keep us posted as to how you get on!

 

[kaylix]

Thank you very much!
I do have the manual, I just wasn't clear on adjusting screw A or B.
I removed the oil tank early in the year, I forgot about that linkage. Thanks for the reminder!

 

[Blkrvrbart]

I’m right with @mrcid and @Stomp10 Your carb problem was a stuck open needle and seat and I f you’re using premix you don’t need that rod that’s missing. It’s the rod to vary the oil injection rate. I took mine off when I deleted the oil pump and started using premix.
The basic setting on your idle mixture screw is 1 1/4 turns out from all the way in. When I say all the way in, that means lightly touching all the way closed, not cranked down tight. You want any variable components to be treated gently, but assembly screws to be torqued correctly. Sorry for the late chime in.

 

[kaylix]

Thanks everyone
She's running great after the carb rebuild!

 

[Diplomasta]

Sportjet needs the oil injection system. Spark plugs are surface gap and will foul with premixed gas. Also, the motion sensor by the oil pump is tied into the Cold start TKS system. And you DO want that to work properly. The reason they didn't just use a choke or primer, like the 175 outboard, is because sport jet is always under load. Never in neutral. Engine does not have a chance to warm up under no load. Cold starts without tks with shorten the life of the engine. In summary, you are not an engineer. Don't deviate from original configuration unless you want to branch off into an alternate timeline of new, never before seen issues and quirks. Happy jetting.