Stalling out a Dynamite .12 SPD

[CNSelf]

I've been "bench racing" this truck of mine for a while now and finally today I got all the parts and pieces I needed to get it running (busted radio). On the stand the engine was running fine, idling a whole tank at a time with the wheels on the ground. Manually moving the servo I could get it and keep it revved, though it was "boggy" getting up to higher RPM, I figured I could just lean out the high end when I got the radio back together. Also, lots of fuel splashed from the exhaust.

Today I fire it up and instantly burn up a glow plug, something this engine has never done. Now, with the fresh glow plug (and a longer fuel line to accomodate a recommended fuel filter) the engine is more difficult to start and will not idle at all. 90% of the starts I didn't even have time to put down the glow starter and pick up the radio before it died. After several hours of small adjustments to the idle speed screw and the low end needle, I can drive the truck about 10 feet before it dies. It accelerates very slowly, and even at half throttle usually the engine will die before it builds up much rpm. Still a lot of fuel coming from the pipe.

I'm a novice to nitro, but my gut tells me it's getting an inconsistent flow of fuel, judging from the irregular idle sound. I also notice fuel moving back up into the pressure line. I've removed the filter and gone back to the 2" tubing from tank to carb (It's a GT so it's a short link). I also reset the Dynamite to factory settings (low 4.5, high 2.5 no idea about the idle speed needle, can't find factory specs for it).

Summary:
Engine is slow to start occasionally
Engine does not idle well
Car only moves a few feet and engine dies
Fuel in the pressure line
Fuel "sprays" from pipe

I'd appreciate any suggestions before I start adjusting it with a ball-peen hammer... :trout:

 

[Arrow]

its probly VERY rich... and if the glow plug isnt the same one as before you made need to re tune it

 

[CNSelf]

I'm happy to say that I got it all worked out. Ditching the extra fuel line and fuel filter did the trick. I'm not sure if it was faulty or just throwing it off enough to magnify a problem I already had, but with a short line from tank to carb it runs again. It's not perfect yet but I'm getting there.

 

[TeamLosiNXT]

I'm looking for the factory settings for the .12SPD? Does anyone have them. I searched google for about an hr and can only find seetings for the promix carb on a .15 marine engine. It says 2 turns high and 7 on the low. Anyone know what the manual says or know where i can find one?

 

[Timmahh]

by the sounds of the fix, you either have/had an airleak at the fuel filter, or maybe elsewhere in the line you removed. fuel spraying from the exhaust says its rich.

Keep in mind the H needle not only adjusts the fuel flow for the top 2/3rds of the rpm range, but it also adjust fuel flow for the whole motor. if you high needle is to far open, then you ll likely flood out, even at low rpm where the low needle handles the fuel flow.

 

[HeartBreak]

My experience on small block engines is that they don't like very long fuel lines. On my OS CV.12 (that I sold a while back), it wouldn't run worth anything in my GT with a line longer than 4 inches. My OS TZ.12 is the same exact way.

Pressure line on the other hand, they tolerate a longer one with no problems. It's just the fuel pickup line. It's kind of a long straw drinking concept; the longer the line, the harder the engine has to work (or suck) to pull the fuel from the tank.

 

[TeamLosiNXT]

Finally got it right, put back to factory specs and now its running like a champ. Damn carbs, I'm a make EFI for RC's