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NGH GT17cc petrol engine starting issues


Jamie sawyer
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Evening gents, I have bought the engine above. I have adhered to the instruction and mixed a 25/1 petrol oil mix. I have tried everything in my eyes to start this engine and not even a pop. Well there was at the very start but it certainly didn't take.. it was just a fire pop about 2 or 3 times and after that it just hasn't done it since.

I have even bought an electric starter to try and get it going but not even a fire from it while trying this.

I have always flown glow and was very excited about the prospects of a petrol but I am some what disheartened slightly. The spark plug is getting a spark. Fuel is getting to the carb. I have the low needle at 2 turns and high end needle at 2 turns as per instruction .....

There is 100% fuel getting to the carb....and a spark... I just don't understand how it is not taking. Running an 1100 mah 4 cell pack as ignition with a battery monitor installed so the battery is not the issue either.

PLEASE HELP any suggestions are welcome please angry

Jamie

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Hi Jamie Try lipo with volt regulator. The Nimh batteries don't deliver enought "power" unless they are full. That's why you had a couple of pops at the beginning and then nothing. Another option would be the old NiCad, but with lipos around I wouldn't bother

Edited By AVC on 11/01/2016 21:12:05

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Jamie, you could try with the battery fully charged, but the problem is that the engine is not broken in, so before it fires the battery probably will loos "punch"

Opto kill switches normally would accept 3s but you only need 2s for the same result. For testing purposes you may try with one 3s but if it works I would install a 2s in the model 

Edited By AVC on 11/01/2016 21:34:37

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Are you sure fuel is getting through? My first experience with a petrol engine was similar. It took ages to get it going and I was so glad to have the help of the club petrol engine expert. We squirted neat fuel into the carb venturi. turns out the membrane in the carb needed to be thoroughly soaked with fuel before it would pump properly. Once we got the engine going subsequent starts have been a doddle.

I'm running my ignition on 4 NIMH low discharge cells and have had no issues at all doing so. No issues after a day of flying. 

If you want to rule out the lack of punch in the spark though, you could use an old speed controller if you have one with a BEC built in lying around. 

In terms of fuel... I run only the more expensive Shell V Power. Made a whole 1000 RPM difference over the Morrison's normal petrol. I do't think it will make that much difference with starting though.

 

Edited By GrahamC on 11/01/2016 21:56:58

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Hi GrahamC I have done that also. I manually fed fuel into carb as it was as you say very sluggish to draw fuel from the tank at first. It's not now and as soon as I give the electric starter a buzz on the spinner you can see the fuel flow at speed up the fuel tube. On the engine there is a short tube that comes out of the carb and into the engine and it is definitely dry of fuel. Is this normal as I would have thought I should have seen fuel in it also ??

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Posted by Jamie sawyer on 11/01/2016 21:36:56:

The spark plug is most definitely getting power as when I turn the prop with plug out it is sparking with a click noise to it.

Jamie, a spark at atmospheric pressure (plug out) is no proof of a spark when under compression with the plug in the cylinder. A broken wire in a coil or a weak capacitor can easily be the difference between starting and not starting.

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Posted by Robin Colbourne on 11/01/2016 23:40:29:
Posted by Jamie sawyer on 11/01/2016 21:36:56:

The spark plug is most definitely getting power as when I turn the prop with plug out it is sparking with a click noise to it.

Jamie, a spark at atmospheric pressure (plug out) is no proof of a spark when under compression with the plug in the cylinder. A broken wire in a coil or a weak capacitor can easily be the difference between starting and not starting.

Fully agree with Robin. In fact, the spark plug should not be tested this way (turning the prop with the plug out), as this can kill the ignition. If you do so (I wouldn't do it...), ensure that the plug is in contact with the engine, although the safest way is using an ignition tester like this

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Posted by Jamie sawyer on 12/01/2016 07:28:48:

Ok thanks guys, with regards to John Stone. Wouldn't a 6.6 volt battery unregulated damage the electronics ? It states max voltage of 4.4 volts ?

You're right Jamie. Some ignition units accept 6 volts or even 7.2 (so the can be run using 2cells lipo), but it seems that the one in the NGH is rates at 4.8, and in this case you cannot exceed that voltage.

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My Evolution 26 was difficult for me to start until someone at the club with experience of petrol gave me some tips. It needs a powerful starter (and battery) that will turn it over quite quickly, it also it helps if I put a teaspoonful of petrol in the carb, and then turn the engine over a few times by hand (ignition off!) to make sure its really wet in the cylinder before switching the ignition on and applying the starter.

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Hi everyone. the voltage regulator arrived this morning and I wired it up with my 3s 1p and have the engine a whirl for 2 minutes on the electric starter. I didn't spend very long in fairness trying but for the short period that I did try there was no fire from the engine. I'll have a go again tomorrow in the daylight. Is there any other possibility that could cause a petrol not to take ??

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You may have done all these...

  • No kinks in pipe work and felt clunk ok
  • Is the vent pipe open to air
  • Is the plug cracked damaged
  • Does the plug cap sit tightly, is there a locking spring ring?
  • Have you opened the carb up (according to JE it's a Walbro) to check for a sticking diaphragm, dirt in the filters, is the float needle at the correct height
  • Does it have a pulse port, if so is it open and clear? Check the pipe is not damaged or split

Sorry if you have done all this but that would be my list

Also I know my petrols like to have a bit of fuel dripping from the carb after priming. Then choke a few flicks, half choke then they fire

I also don't use supermarket fuel

Edited By cymaz on 14/01/2016 06:27:49

Edited By cymaz on 14/01/2016 06:28:38

Edited By cymaz on 14/01/2016 06:32:04

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As Cymaz says, try and prime the engine properly until you can see a bit of petro dripping. Don't put petrol trough the plug hole because this could flood the engine, and potentially damaging it.

If you have another plug, try to use it. The plug may be damaged or the gap be too narrow or too wide.

Have you adjusted the needles? If so, how many turns?

What is the position of the throttle when you try to start up?

Does the tygon has the right section?

It would be useful if you described in detail your start up process step by step.

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