Zenoah runs hards , then dies  
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All Forums >> RC Cars, Buggies, Trucks, Tanks and more >> RC Giant Scale Cars >> Zenoah runs hards , then dies
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Zenoah runs hards , then dies - 11/4/2005 8:45:34 AM   
rainman777


 

Posts: 54
Joined: 2/22/2004
From: Wagga Wagga NSW, AUSTRALIA
Status: offline 		My Marder's ZG22 engine starts fine after a few tugs on the starter. The bulb fills nicely and all is well. However, after 5 or so minutes of hard charging, she starts to die when I open the throttle wide, which eventually gets worse until the merest whiff of throttle threatens a stall. Then she dies. When I look at the bulb on the carb it's empty. Furious pressing gets fuel in but it immediately drains out and there is no chance of getting the motor started.

I can see no fuel leaking but when I press the bulb there seems little movement of fuel from the tank, but bubbles do move on the return line. If I leave the car for a short while, maybe 5 minutes, she'll go again, even responding to full throttle, then it all starts again.

Now I'm guessing this is a blocked fuel filter. DOes this sound like a reasonable assumption? If so, has anybody got tips on cleaning the filters? I have one in the tank and one in the line just after the line exits the tank on its way to the carb (which some have suggested is in back to front - could this be the problem?)

If it sounds like something else, could anybody advise how I could track down the problem?

It's frustrating, as all seems fine then she dies.
       Post #: 1

RE: Zenoah runs hards , then dies - 11/4/2005 10:18:15 AM   
StefanL


 

Posts: 313
Joined: 8/7/2005
From: , SWEDEN
Status: offline 		I had the same problem with my G2D a while back. Ran well for ten minutes, then began to loose power and an empty bulb. The reason was that the carby didn´t suck fuel properly, most likely it had to do with the fiber gasket that regulates the pumping action. I could have bought a carb rebuild kit, but since I wanted a performance air filter I bought a brand new 230/260 carb instead (it has the choke on the carb au contraire to the carb on the G2D).

Now it runs like a champ.

You suspect the fuel filter might be the culprit, so you COULD try running the car without a fuel filter just to find out if that is the problem (clean the tank first!), but it seems unlikely to me.

Don´t drive the car too much though in the present state because the enginge runs lean and might be damaged in the long run.

Stefan

_____________________________

FG Marder 1:6 31cc Oneill Racing engine, Tuned pipe, one off body. Spektrum DX3

(in reply to rainman777)
       Post #: 2

RE: Zenoah runs hards , then dies - 11/4/2005 1:58:34 PM   
MrMikeG


 

Posts: 1205
Joined: 9/24/2005
From: Mildura, AUSTRALIA
Status: offline 		Clogged fuel line or,,, clogged vent on the tank. Try unscrewing the tank lid when it stops, if it sounds pressurized you know it is not venting properly.

(in reply to StefanL)
       Post #: 3

RE: Zenoah runs hards , then dies - 11/4/2005 4:10:54 PM   
kengentry5000



Posts: 1296
Joined: 7/20/2005
From: Greensboro, NC, USA
Status: offline 		A non-engine suggestion: Are you running plastic spur and pinion gears? If so I wonder if the gears have a problem where when they are cold they mesh fine but when they heat up one or both expand. This expansion would cause the gears to bind up and cause the engine to die.

I have suspected this before and replaced my gears and things work better for longer periods of running.

Maybe my theory is wrong...StephanL and MrMikeG, what do you think?

Ken

_____________________________

Firehammer with Zen 26cc and FG 8485 limited slip diff (no more "sit and spin" - just hooks up and goes).

(in reply to MrMikeG)
       Post #: 4

RE: Zenoah runs hards , then dies - 11/4/2005 6:42:35 PM   
StefanL


 

Posts: 313
Joined: 8/7/2005
From: , SWEDEN
Status: offline 		kengentry, I´m not all too keen on the spur and pinion gears idea as the cause of the problem...

The gears would in no way cause the fuel bulb to empty, so the problem is in the fuel supply somehow. Either clogged lines or bad suction in the carburetor.

It won´t kill the motor if the gears are too tight, the engine would just not rev up. The clutch would disengage at lower revs and the engine would idle normally. The gears would wear out very quickly or melt due to friction heat. The only way I can see that expanded gears could kill the engine is if the clutch was somehow misadjusted or faulty and and did not retract at lower revs. But then the enginge wouldn´t idle at all, even with cold gears.

Stefan

_____________________________

FG Marder 1:6 31cc Oneill Racing engine, Tuned pipe, one off body. Spektrum DX3

(in reply to kengentry5000)
       Post #: 5

RE: Zenoah runs hards , then dies - 11/4/2005 8:25:36 PM   
Oneill Brothers Racing



Posts: 285
Joined: 4/9/2004
From: Torrance, CA, USA
Status: offline 		There is a small metal screen in the bottom of the carb. There is one silver screw on the bottom of the carb that you have to take out. I would check that screen to make sure it is clean.

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www.oneillbrothers.com

(in reply to StefanL)
       Post #: 6

RE: Zenoah runs hards , then dies - 11/4/2005 8:53:47 PM   
StefanL


 

Posts: 313
Joined: 8/7/2005
From: , SWEDEN
Status: offline 		I cleaned the screen first when I encoutered the same problem. It was easy to do since it didn´t require a complete dissassembly of the carb. There was some debris there, but cleaning it didn´t help much at all.... Later when I cleaned the entire carb I found that the fiber gasket that regulates the pumping was worn. ie. the two flaps of the gasket was not lying flat agiant the surface. I suspect that that was the reason for the poor performance, but I didn´t find out since I bought a new carb instead.

A good thing, because later when I crashed the car with the new carb, the white plastic part where the fuel return attaches broke. So I scavenged the one from the old carb... The car was running in no time! Sometimes a problem leads to the solution of another.

_____________________________

FG Marder 1:6 31cc Oneill Racing engine, Tuned pipe, one off body. Spektrum DX3

(in reply to Oneill Brothers Racing)
       Post #: 7

RE: Zenoah runs hards , then dies - 11/4/2005 10:46:33 PM   
rainman777


 

Posts: 54
Joined: 2/22/2004
From: Wagga Wagga NSW, AUSTRALIA
Status: offline 		Sounds like I should invest in a new carb. It's an old Marder so maybe the carb is past its best. The fuel venting issue fascinates me - I've been screwing the cap on hard, but maybe I should just tighten it until it's snug. Fuel bubbles out of the cap and after a run the cap is covered in crud glued on with fuel. Having left the car overnight, the fuel bulb is now full of fuel, so maybe it's a pressure/venting issue rather than a blocked filter.

(in reply to StefanL)
       Post #: 8

RE: Zenoah runs hards , then dies - 11/4/2005 11:00:09 PM   
StefanL


 

Posts: 313
Joined: 8/7/2005
From: , SWEDEN
Status: offline 		I don´t understand how pressure in the tank would affect anything. If not it would only make it easier for the carb to suck fuel... I check my tank sometimes and it is always somewhat pressurized after a while, and I have no problems whatsoever.

Nitro engines must pressurize the tanks, their carbs don´t suck fuel. Our gas engines do, but still, I can´t see that pressure would be a negative thing...

If it is the pressure, you can test it easily. Just run the car with the cap almost screwed down or somehow make the tank vent properly. I dunno, screw down the cap down gently with a piece of soft cloth over the opening or something. Should be easy to find out if venting is the problem.

My vote is still on the carb though.

Stefan

_____________________________

FG Marder 1:6 31cc Oneill Racing engine, Tuned pipe, one off body. Spektrum DX3

(in reply to rainman777)
       Post #: 9

RE: Zenoah runs hards , then dies - 11/4/2005 11:33:00 PM   
rainman777


 

Posts: 54
Joined: 2/22/2004
From: Wagga Wagga NSW, AUSTRALIA
Status: offline 		I'm guessing pressure is not a problem, but venting is. If fuel is leaving the tank and air is not coming in to replace it, there will be low pressure in the tank which will prevent the carb slurping up the fuel.

(in reply to StefanL)
       Post #: 10

RE: Zenoah runs hards , then dies - 11/5/2005 9:05:41 AM   
StefanL


 

Posts: 313
Joined: 8/7/2005
From: , SWEDEN
Status: offline 		Well that´s excellent rainman. Good luck with the repairs.

_____________________________

FG Marder 1:6 31cc Oneill Racing engine, Tuned pipe, one off body. Spektrum DX3

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       Post #: 11

RE: Zenoah runs hards , then dies - 11/5/2005 11:48:57 AM   
MrMikeG


 

Posts: 1205
Joined: 9/24/2005
From: Mildura, AUSTRALIA
Status: offline 		I think he is on the right track. Check your vent lines, when you fill the tank some fuel comes out, later dirt sticks to them just like the fuel cap, eventually they clog off. When the fuel pump in the carb has to work too hard it stretches and eventually won't work at all. The pump only works off the piston pulse port, not a very big pulse at all, once the diaphram is stretched enough to absorb the pulse it doesn't pump. A good clean carb should last for years without a rebuild.

(in reply to StefanL)
       Post #: 12

RE: Zenoah runs hards , then dies - 11/5/2005 5:00:22 PM   
2pock


 

Posts: 521
Joined: 9/8/2002
From: long island, NY, USA
Status: offline 		I too had somewhat of the same problem! What my problem was, the gas lines in the tank were pushed in to far and when the fuel level went below it thats when I started having the problems. I first had replaced the line, then I simply pulled out the lines about an inch or so and BAM, problem solved ! ! !

< Message edited by 2pock -- 11/5/2005 5:07:51 PM >

(in reply to MrMikeG)
       Post #: 13

RE: Zenoah runs hards , then dies - 11/5/2005 10:31:44 PM   
No Moa



Posts: 1286
Joined: 1/7/2004
From: Bath, ME, USA
Status: offline
quote:

ORIGINAL: 2pock

I too had somewhat of the same problem! What my problem was, the gas lines in the tank were pushed in to far and when the fuel level went below it thats when I started having the problems. I first had replaced the line, then I simply pulled out the lines about an inch or so and BAM, problem solved ! ! !



I had the same problam with my Bergonzoni, couldn't figure out y the it would stop at 1/2 tank, but then i didn't know the line moves, got it figured out, runs great now.

_____________________________

My wife says i'm insane with all this R/C stuff, and i say, i agree!

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       Post #: 14

RE: Zenoah runs hards , then dies - 11/6/2005 11:43:09 AM