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Post-carb-rebuild disappointment (30 HP 4 stroke)

R

Rob Gulley

New member
I have 3 carbs I rebuilt with the kits and everything. New gaskets, new float needle, new float hinge, and all the rest. I measured a 14mm float height on all 3, per spec. I tested that the floats were nice and floppy.

I remounted the carbs. I did one test last night where I pressurized the bulb and it hardened. I did another test this afternoon where the bulb also successfully hardened.

I removed the carbs because I had made a mistake with the throttle plates- but I emphasize- I merely drained the float bowls. I did not open any carburetors. I put carbs back on the motor, and now the bulb does not harden and gas comes spilling out of the barrels. First this happened with the middle carb barrel, then I disconnected the fuel tank and let the motor run dry, and then I did another test and gas spilled out of the top carb.

Why is/are the float(s) not sealing the flow of fuel like they should? Why would a minor disturbance cause such malfunction? Did I miss something?
 
Tap the carbs with a wrench while its running and see if it gets the floats working again. When you adjusted the floats did you put finger pressure on the float to bend the tab? If so get new float needles and seats and replace them. Never use finger pressure when checking float level. Pull the float and bend the tab and the check it again. The needle and seat can be damaged real easy only use the weight of the float to check float height.
 
Another possibility did you replace the fuel lines when you rebuilt the carbs? Try draining the float bowls and pump the primer hard to flush out any crap that may be in the float valves. All it takes is a spider leg or a small piece of crap to keep the needle from seating. Allways replace the fuel lines when servicing the carbs!
 
Pull the carbs off and start over. No kits needed just blow air back through the float needle seat. You missed some dirt or there was debris in the fuel lines. When you put the carbs back on it came loose and is getting stuck in the float needle valve.
 
kimcrwbr1 said:
All it takes is a spider leg or a small piece of crap to keep the needle from seating. Allways replace the fuel lines when servicing the carbs!
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Now spiders I have a lot of. Incidentally, do you have any recommendations on how to protect the intake manifold openings while exposed?

By fuel lines, do you mean complete from tank to carb? Or just pre-pump or just post-pump?
 
Docksidemarineservices said:
No kits needed just blow air back through the float needle seat. You missed some dirt or there was debris in the fuel lines. When you put the carbs back on it came loose and is getting stuck in the float needle valve.
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I shall get right on this and report back. You seem to be a knowledgeable mechanic... you're suggesting that I'm not going to ruin the "freshness" of my new gaskets by taking them out again, yes?
 
It is just good practice to change all the fuel lines and at least clean out the fuel pump and see if the diaphram is still soft. That way your not going to gunk up the rebuilt carbs.
 
The million dollar question is. Where is this gunk coming from? Was old fuel dumped out of tank this year?Was new fuel added to old, Has tank ever been inspected&cleaned?No mention of age on your engine,Are fuel lines soft &brittle?
 
Docksidemarineservices said:
Take them apart carefully and you should be able to reuse them.
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More disappointment. I took them apart, took the floats and hinges off. Even though the inlets and the needles were squeaky clean, I squirted a little carb cleaner in the passages and blew it out with low compressed air. Everything else looked clean, too. I made sure all floats were nice and floppy. Put them back on, squeezed the bulb, and lo- stoppage! Hooray. I ran the motor dry.

Today I trailered the boat up north, 3 hour trip. Upon arrival, I squeezed the bulb and gas starts coming out of the middle carb again. So I empty the float bowls. Try one more time, gas still comes pooling out of the middle (and top, to a lesser extent) carb barrel again. That middle carb was always the least "floppy" of the 3, come to think of it.

Here are things I've ruled out, as they were true before these failed tests:
(1) New, clean gas.
(2) New fuel tank, bulb, and line. (NOT cheap, holy crap)
(3) New fuel filter
(4) All 3 carbs rebuilt with new gaskets, new float needles, new float hinges. Floats are old.
(5) Post-pump internal fuel lines, though old, all have been blown out with high compressed air.

This is a 2003 30hp 4-stroke with electric start and power trim. The only thing I haven't inspected, per kimcrwbr1, is the fuel pump. I took that apart once a long time ago for fun and it was regrettable chaos. I'd rather not return to that unless it's the only remaining place to dig up clues.

I'm not convinced this is a gunk problem. I've controlled for dirt and gunk through several iterations of this nonsense. Unless I'm doing something reallllllllly dumb, which is not impossible, these carbs are clean. The float isn't rising for some other reason, methinks. I've done a couple rounds of this and it's always the middle carb that won't seat.
 
johnnygjr said:
Rob, This might sound like a silly question,u sound very competent, do your carb floats,float??
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NO question is too silly at this point. And thank you. And yes, they do float. So I took them apart again this evening and I caught them red handed! Top and middle carb floats were stuck, despite being free the night before. It took finger pressure to move them, gravity could not pull them down.

Here's what I did. I took some carb cleaner and a brass brush to the surface that the float slides against while it rotates on it's hinge. There is some contact between the plastic of the float and the aluminum of the carb. There was some crud build up that had to be hacked away. I also took a cleaner-soaked toothbrush and gently brushed the scale and build up off the float. I also had to boil two gaskets to get them to fit, but anyways. I put them all back together and once hooked back up to the fuel line they did stop the bulb pump pressure when I tried to fill them with fuel.

This is not a victory. I have to run the motor a few times, drain, and fill, to see if the floats are floppin' the way they should.
 
Just disconnect the fuel line and let it run out of gas then pump it back up. A big part of your problem is leaving the fuel in the float bowls. After each use it is good practice to let it run out of fuel after you flush it in a barrel of water. Then your all set for the next outing.
 
Major disappointment. Even after the disassembly I mentioned above where I did yet another gunk scrape, I just now tried to prime the engine with gas using the fuel bulb and gas again came spilling out of the middle carb. This was after letting it sit for a few days of no operation.

I'm at my wits end, and sorely disappointed. Every time something has to be fiddled with, a carb remove-then-reassemble is a whole time consuming operation.

Do I need new floats? Can they warp so that they're too big for their hinging area? The needles are not what is getting stuck.

Help!
 
Have you gone through the fuel pump? Get new floats and needles and pull the carbs apart again. Soak them overnight in carb cleaner and then blast all the circuits good with high pressure water and blow them dry with high pressure air. Install the new floats and needles and check float height using only the weight of the float on the needle. If you need to adjust it pull the float out and then bend it and check it again. put a fuel line on the carb and see if it seats with the carb upside down. flop it over a few times and see if it stops the flow when it is upside down with the weight of the float only.
 
kimcrwbr1 said:
Have you gone through the fuel pump?
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Not yet.

kimcrwbr1 said:
Get new floats and needles and pull the carbs apart again. Soak them overnight in carb cleaner and then blast all the circuits good with high pressure water and blow them dry with high pressure air. 
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I already did all that, with rebuild kits (kits did not include new floats, though).

kimcrwbr1 said:
Install the new floats and needles and check float height using only the weight of the float on the needle.
Click to expand...
I did check the height with the old floats, per the Seloc procedure. All 14mm, per spec.

kimcrwbr1 said:
If you need to adjust it pull the float out and then bend it and check it again. put a fuel line on the carb and see if it seats with the carb upside down. flop it over a few times and see if it stops the flow when it is upside down with the weight of the float only.
Click to expand...
What's this with bending the floats? What part? Is that safe?
 
So I caught the floats in the act of being frozen yet again. This time I disassembled the float bowls and took them out (carbs 1 & 2).

I took a pair of combination pliers and carefully but angrily compressed the ever living sh*t of the hinge of the float. That is, I was compressing the axis of where the hinge pin goes through, in order to try to make that part of the float smaller.

My guess is that, despite my repeated de-gunkings, high operational temperatures were causing the plastic to expand just enough to cause enough friction between the float and the aluminum part of the carb where it sits that it was becoming stuck.

So I had a proper cold start condition (that is, a day after it had been running), and viola! The floats remained free to seal off the incoming gasoline from the primer bulb.

If it does become stuck again I'm just going to order new floats.
 
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