Trouble with carb needles sticking, wondering why?

[hotrod53]

Three times now I had a carb needle stick in the UP (closed) position, and not all on the same carb. These are the rubber coated needles. Each time I took the carb off and the bowl as dry, I remove the float and have to grab the needle/spring with needle nose pliers to free it. I have cleaned the seat with a Q tip and wiped off the rubber coated needle. I guess replacing the needle and seat is thr right thing to do. If I replace them, should I use all metal or rubber coated needles?

In the meantime I removed the fuel line and let the motor use up the fuel in the bowl when I shut it down, maybe I should get in the habit of doing that all of the time?

 

[j_martin]

Re: Trouble with carb needles sticking, wondering why?

When the fuel evaporates, it leaves behind the oil, and maybe varnishes and crap disolved in the oil. If you get in the habit of running out the fuel when you shut it down for any length of time, the floats hang, the valves are open, and the first flush of fresh fuel when you start up rinses everything off nice and clean.

 

[jeffersondodson561]

Re: Trouble with carb needles sticking, wondering why?

What happens when you turn the carb upside down with the bowl removed? Does the needle stay in the seat when you turn it right side up? I have seen customers putting the tang of the float through the holes in the metal part of the float that has caused this on one occasion but I think that was an OMC.

 

[hotrod53]

Re: Trouble with carb needles sticking, wondering why?

I removed the carb and while it was in my hand, I removed the bowl which was bone dry. I then took out the pin for the float and the float was free even before that. The needle has a spring connected to it, I grabbed that with a pair of small needle nose pliers and had to tug a little go get it free. I then balled up a Q Tip to the size of the hole and dipped it in Seafoam, I slid it down in the hole ad spun it around to clean it out. Of course there didn't appear to be anything in it. I also wiped off the rubber nose of the needle before reassembling.

 

[Faztbullet]

Re: Trouble with carb needles sticking, wondering why?

Replace them with Mercury needles that have the grey coating (orange tips) as the older ones swelling due to ethanol and stick in the inlet of seat. Look real close at yours and if you see the slightest form f a ring replace them. The aftermarket needle for the tillston style carbs are junk....

 

[hotrod53]

Re: Trouble with carb needles sticking, wondering why?

I have yet to see the ones with the orange tips, even with an OEM number. Can you tell me where to find them? I believe that the part number is 1395-9022, my motor is a 1977, 4 cylinder, Merc 500, serial #4803973. I also do not see any OEM seats, should I worry about replacing them too?

 

[Faztbullet]

Re: Trouble with carb needles sticking, wondering why?

Seats are non-replaceable and that is the correct part number. The upgraded needles have a grey/silver coating that wears off to reveal the orange tip of needle. If you get them from a local dealer check them as they may have old stock on hand...

 

[stackz]

Re: Trouble with carb needles sticking, wondering why?

old gas left in the carb bowls is turning to varnish and causing the needles to stick. see it all the time when people put up their boats "wet" for a long period. well, I see it more so with atv's due to the area I live in.

brake parts cleaner will get the residue off all the inside parts while you have the carb apart for cleaning.

 

[hotrod53]

Re: Trouble with carb needles sticking, wondering why?

stackz, I agree with you but this is happening over a period of 1 week! I don't think that varnish can form that fast. I'm kinda leaning to the Ethanol explanation and the rubber tips swelling. Hopefully running the bowls down low will resolve the issue. I'm oing to look into a Methanol treatment addative and the new needles if I can find them.

 

[j_martin]

Re: Trouble with carb needles sticking, wondering why?

Methanol doesn't help any. It's just another alcohol with the same problems as ethanol. Same for SeaFoam. It's mostly alcohol. For a shock treatment de-carboning, or a cleaning solvent, it's hard to beat, but it doesn't solve the problems of ethanol.

Alcohol resistant (new-new stock) or ethanol free gasoline are the only solution, especially if you have any way for a little water to get into the gas.

This does seem pretty weird. Is there any way that the fuel got contaminated, perhaps by decomposition of a past era fiberglass fuel tank, or mischief.