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#1 skylinedgtr Dec 29, 2012 08:43 PM

Not another one...
 
I loathed having to write this post as when I've been searching I've seen thousands like this one! Yes.. it's another can't keep my truck running post.

So much information out there, I have spent the past day trying all sorts of things but I still can't keep it running past 15 seconds (that's been my best so far lol)

Some info:
MGT 8.0 - I bought it second hand, never saw it running but I'm assured it runs fine. It's not been run for about 6 months but it has had decent care whilst on the shelf.

The Symptoms:
At first it wouldn't run at all. After playing with the mixtures I have gotten it to run for about 15 seconds without the glow starter attached. (It runs significantly more lumpy without the glow starter attached by the way). As soon as I touch the throttle, it increases revs then dies immediately. If I leave it to idle, it'll die by itself around the 15 second mark. If I squeeze the fuel priming bulb (to force more fuel into the carb) it'll run for longer... almost seems like a fuel starvation issue? Seeing drips of fuel out of the exhaust and a hell of a lot of smoke!

What I've tried
1. Air sealed the entire engine with silicon sealer
2. Checked for air bubbles in the fuel line
3. Constantly checked the glow plug and charge of the glow plug starter
4. Changed mixtures, currently on:
11 turns for the low speed needle (super rich?!)
5.5 turns for the high speed needle
Idle is set to about 1.3mm

Could it be the quality of the fuel, guys? That's the only thing I can think of. The engine is getting nice and warm after a minute or two of it starting and stopping but I'm not noticing it wanting to stay on any longer with more heat.

Manufacturer recommends 3.5 turns for the high speed needle and 4.5 turns for the low. As you can see, I'm far away from those stats just to get it to run for 15 seconds. If I use the manufacturers recommendations, it doesn't even hint at starting unless I feed it some fuel through the carb first.

Any help would be appreciated - I've spent the last day and a half trying to figure this out!

Thanks!

#2 mredzadventure Dec 30, 2012 09:46 AM

Go back to the factory settings If you up the rev's and it dies it's starving for fuel.
How is the compression If it is weak you may need a new piston and sleeve. It could be the fuel I have never had a bad batch but it is worth a try. It looks like your doing everything right. You might want to check all the seals in the carb.

good luck

#3 skylinedgtr Dec 30, 2012 01:38 PM

Quote:

Originally Posted by mredzadventure (Post 23659279)
Go back to the factory settings If you up the rev's and it dies it's starving for fuel.
How is the compression If it is weak you may need a new piston and sleeve. It could be the fuel I have never had a bad batch but it is worth a try. It looks like your doing everything right. You might want to check all the seals in the carb.

good luck

Thanks for letting me know I'm checking the right things :) it's been a while since I've had to fire up a nitro so I was doubting myself!

When I put it back to factory, it doesn't start at all.. not even an attempt to fire. I noticed that when it's back on factory settings, I can't prime the engine using the priming bulb without first opening the throttle. Is that normal :confused:

The compression seems good, it appears to offer a decent amount of resistance when it's close to TDC. I don't have anything to measure the compression with but it certainly feels ok?

Which seals do you mean? Please let me know. I've sealed the engine including the carb area (excluding the mixture screws for obvious reasons). I wound the HSN out, coated the O-Ring with a touch of Mobil1 then wound it back in again.

#4 mredzadventure Dec 30, 2012 02:44 PM

There should be an o ring on the bottom of the carb and the carb assembly should have a few seals on the high speed and the slide part of the carb. It should prime with out the throttle being opened. For giggles and laughs change the fuel line. I wonder if the carb is bad? What is the brand of the engine and brand of fuel are you using. Maybe the needle on the high speed setting is bad give the carb a good cleaning with carb cleaner or some kind of mild solvent. Also check the seal on the fuel tank cap make sure it is not leaking you need a good seal to get the fuel to get to the carb.

With it back at the factory settings put some fuel in the cylinder and see if it will fire. What brand of glow plugs are you using?


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