# Tecumseh Gas Cap Questions



## bds85466 (Jan 15, 2018)

Greetings All,

First time poster here from Minnesota.

First off, I have an older MTD YM 2-stage 24"; 10hp tecumseh snow king engine. Runs great, never really had an issue.

A strange thing happened to me this morning when getting my snowblower ready to throw this morning.

I opened my gas cap to check the fill level and noticed that the metal dish on the underside of the cap was missing. There was another plastic piece and a foam/mesh piece that was still attached, but it looked like the dish had broken/fallen off into the gas reservoir -- I couldn't see it inside, but assumed it fell in. Not knowing what to expect, but still needing to un-bury my driveway, I pulled the two remaining pieces off the cap, and screwed it back on. Gas tank was on the low side, so I thought I could run some gas out and grab that thing out of there later and fix it.

Couple primes and a pull start and we're off...

A short time later, maybe a pass or two, and the thing dies. Sputters for a moment or two and the conks out.

So I open the gas cap, and look inside. Sure enough there's the metal dish in plain sight. At this point I'm thinking, it's probably blocking the flow of gas because it looks to be directly over the outlet on the bottom of the tank. So I tumble inside, find my magnet grabber -- but alas, it's probably aluminum, so no dice, couldn't grab it.

By now I'm running a bit late and don't have time to really get to the bottom of it. I push the dish off to the side of the tank, put the cap back on, and fire it up -- we're back rollin.

Runs for a few more passes, and then same thing; sputters and dies. I'm completely fooled, thinking the dish has blocked the gas again, or a piece which held the dish has clogged the carb or something.

So I open it up, and think for a moment. I put a bit more gas in it, thinking sometimes when these are low, they don't seem to run quite right anyway.

Fire it up, and we're back up rolling for a bit longer. Same thing happens, sputters and dies after a few passes.

So, it's definitely something where the engine is not getting gas for some reason. Here's where my questions start:

1) I've done some reading on your great forum here -- seems that there's a problem with these gas caps that if the dish is not attached or defective, the venting of the fuel system can be way off/non-existent. Could this be what my thrower is experiencing? Fuel starvation due to no venting? It seems to make sense that every time it would die, I opened the cap, alleviating the problem only for a short time. Would a worthy exercise be to run it with the gas cap partially screwed on? Or poke a hole or something? I'm really actually curious how the metal dish keeps the the tank vented.

2) I don't know how that dish was held on inside the cap. Should I be worried about a broken off plastic piece or screw or something floating through my fuel line and into my carb?

3) I saw updated caps were made by tecumseh (likely for this very reason). If I get a new one, do I need to be concerned with the aluminum dish still in my fuel tank? Should I get one of those claw grabbers to get it out of there or possibly drain and remove the tank?

4) Any other feedback or tests to try?

Thanks all in advance, sorry about the novel of a post.

Cheers,

Brian


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## Shryp (Jan 1, 2011)

The broken gas cap is definitely your problem. If you have a small drill bit you can put a tiny hole in the cap until you can buy a new one. Another option would be to take a small needle and heat it up and then you can melt a hole though the cap. These are just temp fixes as you will leak a little bit of fuel out of the hole if you fill the tank too much.

For removing the old piece, generally the fuel tanks are only held on by 2 or 3 bolts and then the fuel line under it. I would recommend removing the bracket from the tank as a lot of times the bolts holding the bracket to the engine are holding the head on the engine. Tip the fuel line up on the tank before removing the hose and then you can dump the gas back into a container to save it.

The fuel tank has a small screen over the opening to filter most debris. I would not be too worried about stuff getting into the carb.


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## JLawrence08648 (Jan 15, 2017)

Yes that's it, fuel venting. The fuel system needs to breathe. Replace the cap and your problem will go away, or drill a small hole in the cap but careful of water getting inn the hole.


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## nwcove (Mar 2, 2015)

+ 1 on the fuel tank venting, keep the cap loose until you can get a replacement.....if air cant get in, fuel cant get out


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## 43128 (Feb 14, 2014)

replace the cap or your engine will act like its having carb issues. dont worry about the disc in the tank it wont hurt anything


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## wdavids (Aug 9, 2017)

Yes, venting. I had the same issues on an older MTD I just bought, replaced the cap, problem solved.


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## RedOctobyr (Mar 2, 2014)

For now, you want to keep the cap partially unscrewed, so the tank can breathe. But the cap might want to fall off, or eventually vibrate itself down, so that it seals a little bit again. 

You could stick something onto the tank threads on one side, then partially install the cap. If you had a strip of foam, even some folded up paper, you could place that vertically on the outside of the tank's threads. Then install the cap partway. The extra item you added might add enough friction to keep the cap in-place. And the gap around the sides of whatever you added would help ensure a path for venting. 

This might be a way to provide venting, without losing your cap, and without having to drill a hole in the top of the cap, risking water getting inside when not in-use. 

An alternate method would be to place a plastic bag over the tank's neck, where the cap screws on. Put a rubber band around the neck of the tank, to hold the plastic bag tightly in place. Now poke a hole in the plastic bag, at the tank's opening, and you have a vented "cap", and you could still install your normal cap when you're finished clearing. No permanent modifications needed. 

Then replace or repair the cap, when you can.


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## JLawrence08648 (Jan 15, 2017)

You could drill a small hole 1/16" or smaller on the side of the neck, less chance of water getting in.


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## bds85466 (Jan 15, 2018)

Wow thank you for the overwhelming responses everyone.

I ordered a new gas cap but now I can feel confident that's the problem.

I will probably try running sans cap or one of these other methods for awhile just to confirm the root cause. Since I got a new one coming, I might try the "drill a hole" method first. Hopefully that solves it.

Thanks again.


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## CO Snow (Dec 8, 2011)

JLawrence08648 said:


> You could drill a small hole 1/16" or smaller on the side of the neck, less chance of water getting in.


Instead of *drilling* a hole, make a MUCH SMALLER HOLE. Start by removing the cap. Get a small sewing needle and clamp it in a pair of vice grips. Heat the needle with a flame (candle, torch, etc) until red hot and barely touch the inside of the cap to melt a hole (making the hole starting from the inside surface will make a smaller hole on the outside surface). Only the TIP of the needle needs to melt though the outer cap surface. Making the hole close to the center of the cap will minimize the amount of melting snow that approaches the hole. I did this with one of my caps and it worked fine - never had a problem with water in the tank.


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## bds85466 (Jan 15, 2018)

CO Snow said:


> Instead of *drilling* a hole, make a MUCH SMALLER HOLE. Start by removing the cap. Get a small sewing needle and clamp it in a pair of vice grips. Heat the needle with a flame (candle, torch, etc) until red hot and barely touch the inside of the cap to melt a hole (making the hole starting from the inside surface will make a smaller hole on the outside surface). Only the TIP of the needle needs to melt though the outer cap surface. Making the hole close to the center of the cap will minimize the amount of melting snow that approaches the hole. I did this with one of my caps and it worked fine - never had a problem with water in the tank.


Thanks for the great idea. I ended up doing something kind of similar last night. I took the smallest diameter nail I could find in my garage and gently started tapping it through the gas cap, from the underside. Once I saw the glint of the nail head poking through, I quit. It actually worked pretty well and left a ridge/mound of deformed plastic around the hole, so it should at least shed water instead of funneling it.

I did fire it up and let it run cap-less last night for about 10 mins. I then tried the modified cap for the same amount of time. Seemed to be running right. I didn't bother wheeling it around very far because it was cold............

At any rate, the new cap is scheduled to arrive on Thursday, and there's little snow "forecasted" between now and then so we should be good.

Thanks all, I appreciate the advice. Cheers.


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## DuffyJr (Oct 15, 2015)

I'm sorry but that metal disk in there may not do any harm but I'm afraid it would keep me up at nights. Next nice day I'd try and get it out of there. Maybe a paper clip unfolded like a fish hook and taped to a pencil or something similar would work.


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## jtclays (Sep 24, 2010)

65156


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## Shryp (Jan 1, 2011)

jtclays said:


> :grin:


I got a pair of those long handle needle nose as well as a pair of the long handle hemostats for doing fuel lines on trimmers/chain saws. The pliers are too bulky and flex a lot, but the hemostats work great.


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## CO Snow (Dec 8, 2011)

When I had the problem, the metal disk didn’t come off like yours. It just stopped venting. It worked fine for 2-3 years with the needle-melt vent until I sold the snowblower.


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