Odd Stalling problem, Troubleshooting suggestions?
 

I have a .21 Vertex engine that came with my redcat 1/8 buggy. I went through the proper heat cycle break in but used more than the reccomended tanks per step. So, heres the problem im having. I went out last night to run my car a little, I started it up and let it warm up some, then drove it from full tank to empty. I noticed no problems whatsoever, good trail of smoke at WOT, no blubbery sounds from a stop to high rpm, no hesitations or anything. After the tank was empty i let the engine cool always leaving the piston at the bottom. filled it back up and started the motor once again. Heres where the problems begin, after running it around at mid throttle up to operating temp, I gave it full throttle and somewhere between mid/high rpm the engine stalled, Nothing has changed between the first tank and second. I started it up and tried again, same deal... it seems to happen after letting off the throttle most of the time but now and then it stalls during acceleration @ mid/high rpm and deceleration at mid/high rpm. after stalling it becomes hard to restart it. if it starts after a stall it will idle fine but randomly stalls. Just for the hell of it i changed the glow plug and tossed the one that was in for the break in period, but no change. I took it to a shop today, and the guy said its running as if theres a clog in the carb, but when he checked it out it was still very clean. the fuel filters are brand new and not clogged. I checked out the fuel lines/tank/pressure line for any air leaks and found nothing. I'm out of things to check on or how to go about troubleshooting this. My needle settings are still slightly on the rich side. If id let the car sit for a bit and throttle it, it would bog some as the fuel built up but other than that i have no reason to believe my settings were to lean, also when the stalling occurs there is no bog or hesitation it just shuts off randomly. Im sorry if im not being clear enough but I will try again today to get a more accurate description on whats happening. The stalling only seems to happen after warm up. Time to sleep, yea this motor has been keeping me up late scratching my head :) Thanks in advance.

RE: Odd Stalling problem, Troubleshooting suggestions?
 

Hmm...:eek:

Definately sounds like an air leak is causing the problem, if you have ruled out a clogged HSN assembly in the carb. If you've already checked the lines and tank for leaks then the next step would be to seal up the engine. There is little point in actually checking the engine for air-leaks, as it is time consuming and requires the engine to be removed from the chassis. Instead, just use tepmerature safe sealent to seal the base of the carb to the crankcase (fine bead around the top of the block and then re-fit the carb to seal), the backplate to the block (remove, seal, re-install) and the exhaust manifold to the block (same deal again).

If you take your time and seal it properly you will eliminate and air leaks, and reduce the chance of air leaks occuring in the future.

If you do this and the engine is still not working properly take a look at the HSN assembly. If there is ANY gunk/dirt etc here it will screw up the flow of fuel to the engine, and give you no end of tuning problems. Just unscrew the HSN completely until it comes out and give it a blast of compressed air/WD-40 etc.

RE: Odd Stalling problem, Troubleshooting suggestions?
 

Hmm

O.k Is the motor idling well?.motor dies at mid rpm?

Low mixture is too rich. excess fuel loads up in the crankcase even at idle .Even before HSN does it's groove

I highly recommend you turn in the low mixture half a turn maybe more [ leaner ]and try it out after half a turn do in steps of 1/8th.But be sure to adjust the idle screw to have a proper idle.leaner low needle will slow the idling of the motor [ more accelaration] and balance a correct idle but idle screw have to adjusted..

Also make sure the break-in is complete. . Take out the glow plug and give it a turn. if it is still tight on tdc more break-in period is needed. It should feel just snug on TDC with the glow plug off.