xXxCellARatOr

My F4.6 engine has just finished 8 gallons. And for the first time ever, it started acting weired. After a while of running, when i give it full throttle it just shuts off. It has never done this before and it is properly tuned. I also tried putting in another glow plug, but it did the same thing. After about 5 mins of running, it would just suddenly shut off on full throttle. I tried richening it by 1 turn on the HSN and 1/2 turn on the LSN. It didnt do anything. Even rich as it was, it still cut out after 5mins of running. The engine still has TONS of pinch. The bearings have never been changed and has been run at a steady 220F on a regular basis. What could be the problem?

twomanytoys

Well just because it has pinch when its cold does not mean it has sufficient pinch when hot. Does it start right back up after it stalls or is it hard to start when hot?

xXxCellARatOr

nope, always starts after 2 seconds of cranking. And the pinch is very tight even when its hot (right after stalling). I know how an engine with no pinch would feel, since i had a 15FE that felt like i was just pulling on a string and nothing was happening since the pinch was completely gone. And it still ran like that for about 1 gallon. But it could not be started after i stopped it. I had to wait for 10mins, and th engine would not idle no matter what, i just had to constantly keep it going without stopping. LOL. My F4.6 is nothing like that, it idles INCREDIBLY low without stalling, and before, i couldnt stall it NO MATTER what i did, when i had a proper tune. It ran, and still runs great with the exception of the cut out after 5mins of running.

twomanytoys

Have you tried to raise the idle a bit to see what heppens. Does it die when you let off the throttle from wide open when hot?

xXxCellARatOr

Nope, thats not the problem. What happens is, i come from full throttle, then from idle i give it full throttle again and it revs just a bit and then Pooof. It just flames out. And like i said, its not lean either. Ive tryed richening A LOT, and ive had the engine for 8gallons now, so i know exactly how its tuned. Its very strange. I took the engine apart 2 days ago to inspect it, and saw nothing wrong with the Piston/Sleeve or anything in the back of the crankase. But i didnt not look at the front bearing or any of the front components.

Thanks for the quick replies.

twomanytoys

What plug do you run?

Midget

Is there smoke coming from the exhaust.
Have you tried replacing the fuel lines...Might be an air leak...Something you couldn't see
when taking apart your engine.
Have you tried cleaning out the needles, Might be some crap on them.

Then info that you have given us so far sounds like it's to lean and starving for fuel.
Even though you have said to us it's not lean, there might be an air leak somewhere....

xXxCellARatOr

OS #8. Its what ive run since ive had the truck. With the exception of the stock plug. But i highly doubt thats the problem, since like i said, ive tryed a BRAND NEW plug and that didnt fix it.

BudBud

I would try another brand new plug, it would not be the first new plug that was bad. A local hobby store got a few cards of OS plugs that sucked air around the eltric wire, all of the plugs on all three cards. It drove several people crazy before we finally figured it out. BB

xXxCellARatOr

Also, another thing, ive almost completely stripped my head button from over tightening. The glow plug still screws in and is a lil just a lil tight. But could that be the problem?

Vigilante212

Im surprised it runs at all with the stripped head button. Get a new one. I would also open it up and check the crank and rod to see if it is sloppy 8 gallons is alot of fuel. If the rod for the piston is sloppy on the crank just replace the rod.

yoster

8 gallons?? I have never heard of a nitro truck/car engine going that long. I've heard plane engines go long, but not the vehicle ones.

m_weinerich

I know a guy with a 12 gallon old LRP .28, 8 gallons is a lot but nothing unusual....

twomanytoys

I have a OS 12CZ that is about 11yrs old going on 13gallons and still running. Its starting to get weak adn the pinch is almost gone but it still runs decent.

xXxCellARatOr

Ok, here is an update. I just took the engine out to do another inspection on it to see if i can find the problem. As i was trying to remove the linkage from the carb, the carb twisted [X(] It wasnt extremely loose, but it was loose enough for me to twist it while i was removing the linkage. I have never touched the carb, so i think it might have finally come loose after 8 gallons. Since ive never touched it, i did not seal it either. Im thinking this might have been the problem. So i took it out, cleaned it, sealed it with Copper Silicone and put it back nice and tight. I will try out the engine tomorrow to see if that fixed it. What do you guys think, could that have been the issue?