I have a Homelite 30cc running on gas/glow. I'm using a new OS four stroke glow plug. It has an 11mm Walbro carb and Bennett muffler. I've also been using the "storage fuel" like AV8TOR has described. This storage fuel is just straight gas and oil that is run through the engine for a minute or so when putting the plane away after a day of flying. Anyhow, lately, when I crank the engine for the first time of the day on the gas/glow mix, it starts and runs good (7800 rpm on APC 18x6) for a while and will then just die off when I'm between low to mid throttle. Sometimes I can keep it running long enough to get in the air and fly for a few minutes before it dies. Then when I prime it and start it again, it will run for just a few seconds and die as if it is only running off of the prime. This starting and running for a few seconds repeats over and over. Then, I hook up my external tank with the storage fuel and prime it until I see the straight gas and oil get to the carb. I then crank it and it runs without shutting off. Even without the glow battery it keeps on running and sucking the fuel through the 2 feet of fuel tubing. Of course it sounds rough because it's tuned for the gas/glow mixture, but never the less, it keeps running until I shut it down. I then hook the plane's fuel tank back up and it will then crank and run, but if it shuts off, it won't crank and keep running. It's almost like it needs to be "reset" with the "storage fuel". I've already rebuilt the carb a couple of times and it's still doing this. Can anyone explain why it's behaving this way? What should I do to fix this problem?

It kinda sounds like the fuel has gone bad. Try mixing fresh fuel to see if it keeps acting up.

Sounds like the diaphram in the Carb. is getting stiff.

The fuel is fresh and I've tried new diaphragm kits with the same results. The diaphragm kits I get from the small engine repair shop has the opaque blue diaphragm in it. Is this OK to use? What else could be causing the problems? Thanks.

check your fuel tank are you using glow fuel fuel line? glow fuel line is not good. also check to see if the fuel clunk in the fuel tank is not in the front of the tank you said it is sucking fuel from your storage fuel can ok so it doesent sound like a carb problem to me be its in the tank michael

Yeah, I would say a tank or a plumbing problem for sure. Even a tiny air leak in a fitting will prevent the pump in the carb from pumping. I use either Tygon or Hayes rubber fuel lines, fuel barbs at every connection, and wrap the connections with wire to secure them.

The carb is fine if it will draw fuel from another source as you say. Your problem is in the tank or the plumbing.

AV8TOR

Is there any other reason that the engine would run off of the straight gas and oil mix imediately after not running on the gas/glow mix? I'm speaking specifically about the fuel. Thanks for all of the responses.

Not unless there is something wrong with your Gas/Glow fuel. Water? Old gas? Otherwise, they will definitely run MUCH better on the Gas/Glow mix than on straight gasoline.

I use a mix of straight gas (actually Coleman fuel) with Sta-bil & Pennzoil in my engines after flying to clear out any alcohol still in the carb or engine before I store my planes. They run MUCH "rattier" on this mix than the Gas/Glow fuel.

AV8TOR

I installed a brand new fuel tank and brand new fuel lines and still had the same problem when I tried to run it. I then ran it off of straight gas and oil mixed 40:1 and it ran much better just like it's been doing. Could it be the fuel? I would suspect it would be the glow fuel/methanol portion of the mix as it runs good with the gas and oil mixture and the gas is the same gas I use in my gas/glow mix. For the glow portion, I'm using 20/20 glow fuel cut in half with straight methanol. Then I use 1/3 of this mixed with 2/3 high test gas. It's getting frustrating to see it run pretty good on straight gas and oil and not run on the gas/glow mix. It's supposed to be the other way around. Any thoughts? Thanks.

Well, it's a "puzzler" for sure. The only thing I can think of is that perhaps the methanol, either your pure stock or once it was mixed with the glow fuel, absorbed water. Alcohol is hygroscopic and absorbs water right out of the air. So if your can was open for a while, especially if it was humid, it might have gotten some moisture in it.

Sorry, but that's the only possibility that comes to mind.....

Well, two more thoughts.... Try changing the glow plug. I have had weird, strange problems disappear with the change of a glow plug on many engines over the years.

Second. Are you sure the engine is able to run rich enough on the Gas/Glow mix?? On a few carbs, I have had to raise the metering lever in the regulator a touch to get them to richen up enough to run well on Gas/Glow. The mixture for Gas/Glow is necessarily richer than that for straight gasoline/oil, and might just account for your problem.

Good luck and let us know how it works out,
AV8TOR

you have ruled out one of the variables already. If the gasoline in the GGL is the same as the gas/oil mix, then its the methanol. Where do you buy your methanol from? Another thing to consider is, even though your fuel jugs are sealed, if the air is fairly humid, the fuel doesnt have to be open long to go bad. The local club "guru" and I have had a few discussions about this. Some of our members dont use fuel can fittings. They just take the cap off every time they fuel up. In manitoba, its fairly humid, and these certain people always seem to have engine troubles of some sort. We keep telling them that its b/c they are always taking the cap off the fuel jug, but I dont think they belive us.
So basically what im saying is, Try all new fuel. I have thought about using fuel pumps to pump the fuel into the jug. Have marks on the jug for the ratios. I think this will help quite a bit.

are you using the same plug to run gas and oil mix are are you changing the plug out ? I thing I read some where here on rcu that gas and oil mix will mess up a glow plug i might be wrong on my gas to glow i just run it dry and use trans mission fluid as an after engine run oil michael

I have a different brand of glow fuel which is 15/17 (nitro/oil) that I use for my glow engines. I think I'll mix a small batch of gas/glow fuel using this with the nitro cut down to 10% using the straight methanol. This should take one component out of the equation. I may try to get a fresh gallon of methanol as well. I live in South Carolina and the weather here is very humid. As for the needle settings, I think they are fine because this engine used to run well on gas/glow and I haven't touched the needles from their good setting. I have, however changed the brand of glow fuel.

It takes more gas/glow fuel to run an engine. So if you are not adjusting the needles you don't have much of a chance of making it run right.

Count the turns it takes to close each needle. That will be your base setting.
Open each needle to the base setting plus 1/2 turn on the low and 1 turn on the High.
That should be a ball park setting.

Hello,
Im not sure, but did you turn around the carb for easier throttle linkage? If i remember correctly, there is a small hole between the crankcase to allow crankcase pressure to pump fuel to the carb. If the carb is turned and the hole is blocked, the engine will run for a little after being primed, but will then die b/c of lack of fuel pressure.

It may stay running on straight gas b/c it takes more fuel to run the engine when using gas/glow than straight gas. It could also be siphining/gravity feeding gas from external tank which keeps it running.
Hope to help,
TFF

are you using a os type f glow plug? and does it prime easy like when you choke it does it draw fuel from the tank to the carb easy or do you realy have to flip it over to get fuel to the carbif you can rock the prop on the compression stroke with the choke on and see it draw fuel to the carb the you can elimate a air leak if not look at the gaskets for the carb mounts also check and see if your back plate and cylinder bolts are tight and not missing and check all your gaskets from what you said you have a fuel problem i run a gas glow its a ryobi 31cc with a 13mm carb and i had to turn my needles out high 2 1/2 low 2 1/2 it will run rich let it warm up be for you take the glow plug starter off then adjust your high end the your low end also check your metering lever like av8tor1977 said also check the little screen in the carb to see if it pluged up it happens when they sit to long i knoe i probley opened up a can of worms but i have read av8tor1977 post on gas to glow and he was right on my ryobi runs sweet one more thing does the homi 30 use a twister carb manifold the carb should have two holes on the bottom make sure you are using the right hole for the pluse port and that your gaskets holes line up with the pulse port holes on the engine this is what i would do also how is your compression high or low if i am wrong on this i am sure someone will let me know but this is what i would check michael

I had a similar problem but it was with a Zama carb. It would run for a few minutes on the gas/glow fuel and then it had real problems in the air. I would then remove the fuel from the carb before leaving the field. When I tried it again several days later the same thing happened. The carb had the original black diaphragm. After that I replaced the diaphragm with a replacement, it was still black but definitely a different material. It worked fine for about 5 or 6 flights and then something happened and it would not work at all. Anyway, after that I replaced the carb with a Walbro having a blue diaphragm and changed to EI. It has worked fine ever since then on gas/oil mix. About 25 flights with no carb problem. It might be that the diaphragm is effected by the gas/glow fuel especially when fuel is flowing at max rate. I suggest changing to a fiberglass diaphragm.

my ryobi 31cc would not start after sitting for a week so i pulled the the carrb apart and found the the fuel inlet screen was all corroded up think the methenal did it cleaned the screen and it worked fine now i use air tool oil for after engine run and put some in the fuel line seams to help michael

normally, gasoline two strokes do not rust inside and do not need after run oil

running E85 or gas/glow will be a need for after run oil?

I have had problems with Zama carbs running Gas/Glow. The diaphrams swell up and then they won't run right.

I am using an "After Run" fuel on all my engines; gas or Gas/Glow now. It is Coleman Camp fuel, with Sta-bil fuel stabilizer, and Pennzoil for aircooled engines at 20 to 1 ratio. I DO NOT FLY WITH THIS FUEL AND DO NOT RECOMMEND DOING SO. I run my regular fuel, whatever that might be, then when I am done flying for the day I drain the tank, put in about a half tank of the "Storage Fuel" mix and run the engine until I am sure all the flying fuel is burned and the engine has nothing but the "Storage Fuel" in it. I then choke it to kill the engine, and drain out the storage fuel.

I was having problems with diaphragms going bad in as little as 3 weeks on my normal gasoline only engines. Since using my "Storage Fuel" I have several airplanes that have been stored for 5 months and then flown with no problems.

AV8TOR

I tried mixing up a batch of new, fresh fuel and still had the same problems. I bought a new carb (Walbro WT-391) and will try it this weekend, hopefully. Thanks for all of the replies. I'll post an update after I try the new carb.

I tried the new carb and got the engine running perfectly. I flew it 3 times yesterday with no deadsticks. I'm using AV8TOR's "storage fuel" technique and hopefully, I won't have any issues related to the alcohol in the fuel. There was obviously something wrong with the other carb. Thanks for all the help.

How long will it run on the "straight gas" and oil mix in that imediately after? I think it is still running on the gas/glow mix somewhat...it takes a couple of min on idle to purge out the fuel the engine was running on first. I have had a engine run on gas/glow for a full min on just a small shot of prime through carb throat, with no fuel line hooked up. Run it longer and Rev it up...see how long it runs then. Hey...get a DLE30....the time I wasted was way too much on gas/glow....just too many hoops to jump with that gas/glow for me. If you like killing time and continually messing around.[X(]..stay with gas/glow. Best Regards Capt,n

I pick a Gas/Glow plane from my fleet, fuel it up and go fly. Doesn't get much easier than that. They are actually easier to use once you have them set up and tuned properly.

But to each his own...

AV8TOR

capt,n

Is just me or is this gas-glow just not your thing?
Go ahead and say what you really think.