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dadzilla-5 · 04-20-2003, 07:05 PM

Hi - I have a GMS 40 that runs well and has lots of power. It starts reasonably well, and has a gallon of fuel through it. The only problem of note is that it won't shut down. Even with the carb barrel closed up tight, it still sits there idling away - at a very low rev, just above shutting down. I sealed up the join between the carb and the body of the engine with some sealer, but no good, it still won't shut down without pinching the fuel line. any ideas what to try next?
Thanks!
zilla

JimMoss · 04-20-2003, 07:47 PM

Have seen the same problem with loose backplates as well.

Jim Moss

recon · 04-20-2003, 09:10 PM

Pretty much every GMS engine has this problem. I have 2 of the .47's one works fine, and the other doesnt shut off. Its not that big of a deal for me, I have it on my old trainer. Ive heard that it might be caused from an air leak in the forward bearings.

R Plante · 04-20-2003, 10:31 PM

we have 2 that came with the bolt that holds the carb in place in backwards. Check that it rotates to pull the carb down when you tighten it up. If it doesn't remove it and reinsert from the other side. Fixed both of ours .

Good luck

Randy

chiroman · 06-24-2003, 07:23 AM

is there a trick to removing that bolt? my gms does the same thing.

Flypaper · 06-24-2003, 11:46 AM

Friend of mine with an MDS 61sealed everything up, still wouldnt shut down. Gave it to me to check out. I put a hose on the carb with a tight fit. Dunked it in a tub of varsol. Blew in the hose. Air was coming out the front brg. as fast as I could blow it in. Sent it back to the HS. He started up a new MDS 32. Second tank of gas it was doing the same thing. Bummer!

FaceDeAce · 03-13-2005, 10:03 PM

This GMS 40 needed the rear bearing replaced this spring. We opted to replace the rear and front bearings.

When I removed the front bearing I discovered that it was shielded on one side, but not sealed. The shield does nothing for this bearing as it is behind the drive washer. It results in a very significant air leak. The air will go through the bearing as fast as you can blow it through. It is no wonder that this engine wouldn't shut off and was sometimes tempermental to tuned.

I put a sealed front bearing in. No shields. I left the outside seal intact and cut a small slit in the inside seal so some oil could get to it. The sealed bearing made a huge different on this engine. There is no longer a major air leak through the front bearing. The engine is now super easy to tune, very reliable, and yes it does shut off when you chop the throttle closed.

If anyone is having tuning problems with their GMS 40-47, or that your engines do not shut off and you have corrected all other potential sources of air leaks (carb and back plate) -- just replace the front bearing with a sealed bearing.

TTFN!

Wayne MIller · 03-14-2005, 07:36 AM

Hi,

The easiest way to find if you have an air leak is to idle the engine, then spray WD-40 where you suspect the leak is, if the engine acts up where you spray, that is the problem. Spray around the base of the carburettor, the body of the carburettor, the engine back plate, then the front bearing.

Spray the front bearing last, otherwise the spray may migrate back to the other leaking areas giving you a false report.

Also, check out this thread on GMS I started at RCU regarding GMS problems:

http://www.rcuniverse.com/forum/m_22...tm.htm#2290854

You should read it all, but most of the good stuff is near the end of the thread.

Let me know how you make out.

Fly4Fun,

Wayen Miller

chiroman · 03-14-2005, 08:12 AM

Quote:

Originally Posted by Claude Paradis

If anyone is having tuning problems with their GMS 40-47, or that your engines do not shut off and you have corrected all other potential sources of air leaks (carb and back plate) -- just replace the front bearing with a sealed bearing.

TTFN!

Will this help with a GMS 47 that dies on tight loops?Apparently this is a common problem as well but only with the 47 that I am aware of.

Wayne MIller · 03-14-2005, 08:21 AM

Hi Chiroman,

Drilling the GMS brass insert, as described in the above thread, typically takes care of:

Engine quitting just after takeoff
Engine quitting on loops
Difficulty adjusting high end (high end has a broad range of adjustment)
Difficulty adjusting transition

The thread also describes a couple of suggested tuning procedures.

Also, I find the engine likes the Fox idlebar plug, this is fine with me since they are very reasonably priced and seem to work in almost all engines. I fly mine with 15% nitro and fuel with at least some castrol in it.

Hope this helps.

Fly4Fun,

Wayne Miller

04-20-2003, 07:05 PM	#1
dadzilla-5 Guest Join Date: Mar 2003 Feedback: 0 / 0% Posts: 20 Total Props: 0	GMS won't shut off! Remove this ad - become a site supporter! Hi - I have a GMS 40 that runs well and has lots of power. It starts reasonably well, and has a gallon of fuel through it. The only problem of note is that it won't shut down. Even with the carb barrel closed up tight, it still sits there idling away - at a very low rev, just above shutting down. I sealed up the join between the carb and the body of the engine with some sealer, but no good, it still won't shut down without pinching the fuel line. any ideas what to try next? Thanks! zilla
	.

04-20-2003, 09:10 PM	#3
recon RCC Master Contributor I am: Brady Join Date: Jan 2003 Location: Standard, Alberta Radio of choice: Futaba # of RCs: 6 Feedback: 0 / 0% Posts: 1,052 Total Props: 0	Pretty much every GMS engine has this problem. I have 2 of the .47's one works fine, and the other doesnt shut off. Its not that big of a deal for me, I have it on my old trainer. Ive heard that it might be caused from an air leak in the forward bearings. __________________ MAAC #63500
	.

03-13-2005, 10:03 PM	#7
FaceDeAce RCC Supreme Contributor I am: Claude P. Join Date: Sep 2002 Location: Great Western Radio of choice: Futaba 7C and 9C, Prism 7x # of RCs: 20+ Feedback: 8 / 100% Posts: 2,092 Total Props: 1	This GMS 40 needed the rear bearing replaced this spring. We opted to replace the rear and front bearings. When I removed the front bearing I discovered that it was shielded on one side, but not sealed. The shield does nothing for this bearing as it is behind the drive washer. It results in a very significant air leak. The air will go through the bearing as fast as you can blow it through. It is no wonder that this engine wouldn't shut off and was sometimes tempermental to tuned. I put a sealed front bearing in. No shields. I left the outside seal intact and cut a small slit in the inside seal so some oil could get to it. The sealed bearing made a huge different on this engine. There is no longer a major air leak through the front bearing. The engine is now super easy to tune, very reliable, and yes it does shut off when you chop the throttle closed. If anyone is having tuning problems with their GMS 40-47, or that your engines do not shut off and you have corrected all other potential sources of air leaks (carb and back plate) -- just replace the front bearing with a sealed bearing. TTFN! __________________ Work Hard, Play Harder
	.

03-14-2005, 08:21 AM	#10
Wayne MIller RCC Supreme Contributor I am: Wayne MIller Join Date: Aug 2004 Location: Kitchener/Drumbo, On Radio of choice: Hitec A9 JR 9303 # of RCs: 19 Feedback: 11 / 100% Posts: 2,169 Total Props: 9	GMS Quitting Hi Chiroman, Drilling the GMS brass insert, as described in the above thread, typically takes care of: Engine quitting just after takeoff Engine quitting on loops Difficulty adjusting high end (high end has a broad range of adjustment) Difficulty adjusting transition The thread also describes a couple of suggested tuning procedures. Also, I find the engine likes the Fox idlebar plug, this is fine with me since they are very reasonably priced and seem to work in almost all engines. I fly mine with 15% nitro and fuel with at least some castrol in it. Hope this helps. Fly4Fun, Wayne Miller
	.

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04-20-2003, 07:47 PM	#2
JimMoss RCC Supreme Contributor I am: Jim M Join Date: Sep 2002 Location: Oshawa, SE Zone Feedback: 4 / 100% Posts: 2,569 Total Props: 1	Have seen the same problem with loose backplates as well. Jim Moss __________________ Jim Moss MAAC 16236 IMAC 3716 My Old Gallery: Straighten Up & Fly Right!
	.

04-20-2003, 10:31 PM	#4
R Plante RCC Contributor I am: Randy P Join Date: Dec 2002 Location: Stettler Alberta Feedback: 7 / 100% Posts: 477 Total Props: 4	we have 2 that came with the bolt that holds the carb in place in backwards. Check that it rotates to pull the carb down when you tighten it up. If it doesn't remove it and reinsert from the other side. Fixed both of ours . Good luck Randy
	.

06-24-2003, 07:23 AM	#5
chiroman RCC Apprentice Join Date: Mar 2003 Location: Charlottetown, PEI Feedback: 0 / 0% Posts: 95 Total Props: 0	is there a trick to removing that bolt? my gms does the same thing.
	.

06-24-2003, 11:46 AM	#6
Flypaper RCC Pro Contributor I am: Gord C Join Date: Sep 2002 Location: kingston Ont. Feedback: 1 / 100% Posts: 1,863 Total Props: 8	Friend of mine with an MDS 61sealed everything up, still wouldnt shut down. Gave it to me to check out. I put a hose on the carb with a tight fit. Dunked it in a tub of varsol. Blew in the hose. Air was coming out the front brg. as fast as I could blow it in. Sent it back to the HS. He started up a new MDS 32. Second tank of gas it was doing the same thing. Bummer!
	.

03-14-2005, 07:36 AM	#8
Wayne MIller RCC Supreme Contributor I am: Wayne MIller Join Date: Aug 2004 Location: Kitchener/Drumbo, On Radio of choice: Hitec A9 JR 9303 # of RCs: 19 Feedback: 11 / 100% Posts: 2,169 Total Props: 9	Hi, The easiest way to find if you have an air leak is to idle the engine, then spray WD-40 where you suspect the leak is, if the engine acts up where you spray, that is the problem. Spray around the base of the carburettor, the body of the carburettor, the engine back plate, then the front bearing. Spray the front bearing last, otherwise the spray may migrate back to the other leaking areas giving you a false report. Also, check out this thread on GMS I started at RCU regarding GMS problems: http://www.rcuniverse.com/forum/m_22...tm.htm#2290854 You should read it all, but most of the good stuff is near the end of the thread. Let me know how you make out. Fly4Fun, Wayen Miller
	.

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