New Savage XL engine stalling when letting off the throttle

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MikeK1981

MikeK1981

ChondroManiac
Messages
2,037
Location
Humboldt, CA
Okay, I had the engine running sweet but it was running between 270 and 290. When I started out it had half a tank and when it ran out I refilled it and to out into the street so I could test the shifting. I immediately started having a problem with it not getting warm enough and stalling when I let off the throttle. Could this be the half tank lean issue I've heard so much about? I mean it went from running good but really hot, then back to the stalling problem and running too cold. Does the tank level make that much difference? I turned the HSN like a quarter turn clockwise from where it was running good trying to lean it out more and it was still stalling and having a hard time warming up. Is this the tank level or do I just not have my needle right yet? Also, the I did adjust the LSN a little clockwise and it seems to have really good throttle response and acceleration, it even runs smooth at top speed it just keeps shutting down on me when I let off the throttle. You can hear it bog a bit like it's loading up on fuel or something right when you let off, or could it be running out of fuel when I let off? All signs seem to point to the fact that it's too rich, slightly wet plug, cool running temps, stalling. I'm going to have to run it from half tank again to see how it acts. Other than this problem the truck is great, very fast, wheelies pretty easy at low speed. I just need to lower 2nd gear a little more and solve this stalling issue and it will be good to go. What is the best way you guys have come up with to address the half-tank lean issue?
 
leave the msn at stock and seal over it with some rtv and when you let off the throttle it could be shuttin off due to the idle screw isnt set right. with the carb slide closed you should have 1mm gap in the carb so when your off the throttle it wont close all the way and it will keep the engine running for ya.
 
OK I have set everything back to stock and now the damn thing won't start. And... since I have been trying to start it so much I have ruined my second starting shaft. I am starting to get very discouraged with this engine to say the least. I don't even know what to do now except call HPI in the morning and tell them my situation.
 
Check your glow plug and make sure its good. Since the motor has been broken in, lean the HSN one full turn and it should be easier to start, then you can tune from there. Good luck
 
thanks i'll try that as soon as i figure out a way to start it. I would just go buy a pull start but I'm sure my local store doesn't have that or the start shaft in stock so it looks like I'm down for a while again, already!
 
Turns out one of my clutch shoes was dragging on the flywheel and not seating properly. I fixed that problem but now my carb is way out of adjustment and I could not get it to start at the factory settings so ill try leaning the HSN some and see if it will fire.
 
I posted about this in more detail in the engine section but I think it was overheating during high revs and that was causing the motor to quit. I think I've got the MSN sorted out now and it is running much cooler 220 to 235 with the body off.
 
hello,
i bought a lrp zr.30 ( i will post a review) and i am in the 5th tank
now these is something that i noticed:with the engine shuted i cant pull the truck backwards
i mean that the truck doesnt go back if i push it
other than that no problem
please tell me what this is
thanks
 
Don't mean to hi-jack but this sounds like a probem I had with mine. I have the k5.9 and I have read that some people run theirs at 280 but everytime mine gets much over 260-270 it stalls out when I let off the throttle but as long as I keep it closer to 230 like the book says (with temps in the high 250's when sitting still for a minute) it runs for as long as I want and idles for as long as I want. I know this is a different engine but when he said his problem was from 260 degrees and up it reminded me of the problem I have. Could this be an environmental issue like location, or different weather in different areas affecting the peoples engines differently even though they may have the same engine?
 
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Every motor is different and will run at a different temp. A lot of things affect the tune and temp of the motor of a motor, including air flow to the engine for cooling and fuel used. DO NOT tune the motor to temp! Tune it to performance and a good trail of smoke coming out the pipe. Once you get the tune good and know what temp range your engine likes to run at, temps are a good thing to check on the fly to see if everything is going ok.

Running a motor too rich just to keep the temps down is just as bad as running a motor too lean.
 
My problem is that when the motor seems to run best with good top speed and low end power, I start getting up to 260-270 and my motor quits running almost every time it settles to idle. The only way I have gotten rid of the stalling issue is to keep my temps down. I am however going to try making tiny adjustments to the carb to try and "push the envelope" between good power and the temps that cause my engine to stall. It seems to be OK in the 250's but as soon as it goes higher it does not want to stay running. The way it is now I run 230-245 so I'm going to try and lean it a tiny bit to get around 240-255 and see how that goes and I should get a little better performance.
 
Check the mid-range needle on the right side of the carb to make sure it is still flush. If the motor runs well at WOT and is not seem like its cutting out or has a "hitting a rev limiter" type sound, but cuts out when you let off the throttle, richen up the LSN a tiny bit. Sounds like you have the engine close to a good tune, just need to tweak it slightly.
 
AllanQ said:
Running a motor too rich just to keep the temps down is just as bad as running a motor too lean.
Click to expand...

I don't know about that Allan, if I had to pick I'd run my engine rich every time. Am I missing something?
 
Running a little rich is not bad....what I meant was running it too rich just to keep temps in a certain range will lessen the life of the motor, just like running it too lean. I busted a crank pin because it was too rich, had lots of carbon build up also.
 
Thanks for the help. My MSN is still flush but there is almost a quarter of a turn that you can make in either direction and it still looks flush. How sensitive is the MSN? Will this small of an adjustment throw my carb off? I'm not exactly sure how the MSN interacts with the other needles so I don't really know how to tell if it is off or not.
 
as long as its flush you should be good. What I do, is turn that needle about a half turn to the right and put a dab of rtv to keep it in place becasue it tends to walk a little. Other than that I recommend not to adjust the MSN. Sounds like you are close to getting it right. Lets us know how it goes.
 
Yeah thats what I do. To be honest, not really sure exactly what it does, I think it restricts the mixture a little at idle, but anyway, that was a setting I was told to put it at when I got my first axial and have not had any issues. I still think you may want to slightly richen up that lsn a touch and see how that works for ya.
 
OK I don't think putting the long fuel tube between the tank and carb did anything. I'm still having trouble with heat and even when the temps are down I'm stalling out when letting off the throttle. I'm going to call HPI tomorrow and tell them this thing is crap LOL! I have tried everything and have not been able to solve my stalling issue. It only does it when going from a lot of throttle to no throttle and sometimes I can hear it bog and save it by blipping the throttle but other times it just stops instantly. I thought it was due to high temps but today it was doing it at 220 and under. I have tried adjusting the low speed in both directions and compensating for the idle and nothing has gotten rid of this problem. Did I just get a bad motor or something? Maybe air leaks? I'm not taking the whole motor apart to seal it up when I just paid that much money for it, that's BS. I guess I'll just have to see what HPI has to say.
 
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I was thinking about this... could my problem be caused by having the carb opening set too small at zero throttle, thus allowing less air in, and I have just compensated for this by running the motor leaner to get the mix right? Could this be why my engine seems to run good but eventually gets too hot AND be causing my stalling issue because the motor still has fuel pressure when coming down from high revs but the carb doesn't allow enough air in when it's closed quickly, kind of flooding the motor with too much fuel and not enough air to burn it? It's hard to tell what 1mm is EXACTLY when your just eyeballing it down inside the carb, I thought I had it pretty close but I read some other places 1-2mm so I opened mine up some more and ill have to re-tune my needles AGAIN LOL! But we'll see if this helps my stalling issue and I should be able to run a little richer, helping my temps too. I'll let you guys know how it goes tomorrow.
 
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It could be the idle setting, and it doesn't hurt to bump it up a little. But if you are between 1-2mm and flooding out, I still think thats an indication the motor is still running too rich and when you open the idle screw the motor will idle faster and the truck will start to walk away from you. I am hoping some of the other engine guys are reading, cause its very hard to troubleshoot via the net. Go ahead and try to bump the idle a little and see if that helps. Keep us posted!
 
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OK, I think I finally got this thing sorted out once and for all! I had to turn the mid speed needle a couple turns counter-clockwise and the LSN a couple turns clockwise, so the MSN is out from flush and the LSN is in from flush if that makes sense LOL. Turning the MSN this way was the only thing that got rid of my stalling issue, and it ran way more rich so that is why the LSN is turned in to compensate. It is my understanding that these two needles work together so I guess it makes sense that one is in and one is out but why this solved my stalling problem I'm still not quite sure. I also did the Uniflow tank mod and my temps ranged from 220 to 230 for most of the tank and about 240 for the last quarter inch of the tank. It did peak a little right before it ran out of gas to like 260 but it was only like the last 5 seconds when the idle went up and then ran out of fuel and it was standing still. I can't say for sure that it was the tank mod that helped my temps so much because I also made drastic changes to my carb but I can say my temps only varied a little from full to empty! It seems that this mod does help. Also, since my truck isn't stalling I can finally get on and off the throttle hard without worrying about it stalling. The truck seems to have quite a bit of blue smoke like maybe it is a little rich, but it is performing extremely well and keeping temps right so I think I'll leave it for now. It may seem like a lot of smoke to me because the only other nitro I have is a Super Nitro RS4 with the .15 in it and maybe being so much smaller it doesn't smoke as much as a big-block. Do the bigger engines naturally let out more smoke, even though they are running lean enough, when compared to a smaller motor? This may be obvious since it IS burning more fuel LOL, but I just thought I'd ask anyway.
 
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