Clean up that carb

[stray]

Why replace the tamper cap? Now you cannot adjust it. I did not know of this cap when I cleaned mine. I guess I missed something.

To keep me from tampering with it again. LOL

 

[stray]

My PT 422 2003 model Robin engine started loping. Pretty bad this time. Any way to make a long story short I found that a plug or cap must had fallen or come out. I had cleaned and took apart and blew out but nothing helped. And then I noticed a port that look cleaner than it should be especially when it was below and outside the air filter. With the engine running and it loping as it was I reached in and put my finger over that exposed port. Low and behold the engine smoothed out and ran like new. Here are some pics to help explain.

Ya it is. On top of some old asbestos gasket material.

 

[SwampmanLA]

After several hours of seat time today moving limestone and sand, I began to smell gas from my 422 with a Robin. Then the thing began to stumble at higher RPMs. I had to finish my work at just above idle. Well after getting it back to the garage and letting it cool down a bit, about two beers worth, I pulled the carb apart again. What I found was the float needle valve was stuck causing gas to flood the carb. I guess that was where the gas smell was coming from. Well that was an easy fix but I did stumble onto a few interesting things doing this.
1. There are five holes around the intake of the carb. These are overflow tubes and when the needle value is stuck gas will pour into your carb even when the engine is shut down and the key off.
2. The fuel shut off solenoid value is downstream from the float needle valve. What this results in is the ability for gas to enter the carb, and the engine through the overflow tubes, with the key off and the needle valve stuck in the open position.
3. Even after cooling for a couple of beers once I had the top off of the carb the gas in the bowl was boiling!
So I guess the moral of this story is that if you don't have a gas shut off valve between your gas tank and engine, you need one!

 

[MuncyBob]

I want to install the fuel shut off valve. Is this something readily available say at a NAPA pats store? I'm guessing it's just a simple on/off valve and all I need to know if the fuel hose inside diameter?

 

[SwampmanLA]

Any auto parts store should have a simple on/off fule valve. Mine was in the small engine section of the store and I think it is 1/4". It is an inline valve so I needed a short piece of hose and clamps to install it.

 

[zman007007]

Bobrip, next time you"re in a Napa or parts store pick up a small roll of gasket material, make your own gaskets and no more waiting 2 days to get a gasket. They come in diff. thickness's. Just get a roll of about 1/16 thick and one of about 1/8" thick. That should cover about anything. Also tell them you want it for gas. Get the paper type material, and you can make your own. It"s not hard and it doesn"t have to be perfect. They also have material made of cork, if you need it. Pete :thumbsup:

 

[BobRip]

Bobrip, next time you"re in a Napa or parts store pick up a small roll of gasket material, make your own gaskets and no more waiting 2 days to get a gasket. They come in diff. thickness's. Just get a roll of about 1/16 thick and one of about 1/8" thick. That should cover about anything. Also tell them you want it for gas. Get the paper type material, and you can make your own. It"s not hard and it doesn"t have to be perfect. They also have material made of cork, if you need it. Pete :thumbsup:

Thanks, good idea.

 

[J_J]

The fuel shut off solenoid was engineered to shut off the fuel in the bowl, so the engine could not draw anymore fuel to the engine after turning the switch off, and to prevent back firing.

Someone makes an electric fuel shut off valve, that would go before the carb. . I have one on an old motor home, and it feeds the gas to the RV generator. A manual valve works just as good, and much cheaper, if you remember to turn it off, and then turn it back on when you next start the PT.

I believe some diesel engines use them also to shut off the engine

 

[MossRoad]

The fuel shut off solenoid was engineered to shut off the fuel in the bowl, so the engine could not draw anymore fuel to the engine after turning the switch off, and to prevent back firing.

Someone makes an electric fuel shut off valve, that would go before the carb. . I have one on an old motor home, and it feeds the gas to the RV generator. A manual valve works just as good, and much cheaper, if you remember to turn it off, and then turn it back on when you next start the PT.

I believe some diesel engines use them also to shut off the engine

My old IH2500b had a fuel shutoff solenoid in the carb bowl of the updraft carb. The carb was lower than about half of the fuel tank. If the shutoff solenoid fails in the open position, it will siphon out the gas tank until the fuel level is lower than the carb. This actually happened to me a couple times. Something about the design of the solenoid made them susceptible to weather. Fortunately, it also had a manual fuel shutoff needle type valve on the side of the fuel filter bowl back under the tank. I always shut that off after use... and many times forgot to turn it back on and died 50 feet down the driveway! :laughing:

 

[catsco]

Sorry to hear about your death so close to the house. And more than once!

 

[cqaigy2]

Sorry to hear about your death so close to the house. And more than once!

So sad i had tears in my eyes too.

 

[BobRip]

On the loop in the hose to prevent flooding: I am now having good results. I originally looped the hose over the top of the tank. The engine required more choking at start up and seem to run a little lean. Not real bad, but I felt I could do better. I then dropped the loop to about 4 inches below the top of the tank. It now starts first time when cold and runs good under all conditions. I sometimes have to crank it a couple of times when hot, but that's OK. No flooding now. My thanks to Continental Engines for their advice on this.

 

[Gale Hawkins]

I should have kept quiet. I am having the same problem of flooding if I start the engine cold with the choke on. I need to crank first without choke and then choke and start.
I talked to Continental Engines and the guy said that when the tank is above the carburetor this tends to happen. I find this a little hard to believe since for nine years the engine was OK. Anyway, he recommend that I put a loop in the fuel line so that the high portion of the loop is at the top of the gas tank. He has seen this help on other engines. I figured it was easy to do and did it. So far its running fine, but I have very limited experience. Has anybody seen this trick/technique before?

Have you tried regular use of Sea Foam. If something works for 9 years corrrectly then stops there is usually physical damage or something is sticking due to varnish, etc. Sea Foam will not fix physcial damage where it will fix your problem or not it will clean up your fuel system/engine if used as stated on the can. I buy by the gallon now. :thumbsup:

 

[BobRip]

On the loop in the hose to prevent flooding: I am now having good results. I originally looped the hose over the top of the tank. The engine required more choking at start up and seem to run a little lean. Not real bad, but I felt I could do better. I then dropped the loop to about 4 inches below the top of the tank. It now starts first time when cold and runs good under all conditions. I sometimes have to crank it a couple of times when hot, but that's OK. No flooding now. My thanks to Continental Engines for their advice on this.

Again I am having problems. When the tank level drops, I have to drop the loop level, or the engine will run lean and die at idle. I have not replaced the needle valve yet. The new one came in, I just think that is not a cure all since Robin recommends a solenoid valve.
I have looked high and low for a solenoid fuel valve with 1/4 inch fittings. I have not seen it or anything close. Does anyone have a suggestion?

 

[J_J]

Page 10 item 20

http://www.generator-parts.com/manuals/generac-rv/0C2901.pdf

 

[BobRip]

Page 10 item 20

http://www.generator-parts.com/manuals/generac-rv/0C2901.pdf

Thanks again. This item was not shown in the drawing. Do you know what kind of fittings it has?

 

[SwampmanLA]

Try this

Vortex Series 12v solenoid valve - JCWhitney

or

Solenoid Solutions:: miniature low watt, 2-way, 3-way and latching solenoid valves-multi valve manifolds-complex finish assemblies

or

Solenoid Valves

hope this helps.

 

[BobRip]

Try this

Vortex Series 12v solenoid valve - JCWhitney

or

Solenoid Solutions:: miniature low watt, 2-way, 3-way and latching solenoid valves-multi valve manifolds-complex finish assemblies

or

Solenoid Valves

hope this helps.

Thanks.

 

[BobRip]

Just thought I would do an update on putting a high loop in the fuel line. This has caused hard starting problems and running issues, so I dropped the loop down. The PT seems to be running fine without it. I think the look was starving the fuel pump. You could see a lot of air in the fuel filter.

 

[BobRip]

Just an update on my carb problems. The engine has been running ok, but hot and cold starting have been a problem. I took the carb top off yesterday and replaced the float valve. Of course I cleaned the carb. I noticed that the choke closing spring seemed kinda of tight. Thinking back to my carb adjustment days, the best operation is when the choke is just loosely closed with engine at room temperature. That way when the engine starts it can pull the choke open some. I remember that I had tightened the spring last year to ensure closing. This turns out to be a mistake. I loosened it (basically unwrapped it one turn). I have started it three times while cold since then. It starts on first try and even if you leave it choked it continues to run at least for a while. Previously if you did not open the choke at just the right speed the engine would flood or lean out and stall. A very critical situation. So far so good. I have also had trouble with hot starts after sitting for several minutes. I am hoping the new float valve will help here.