• Welcome to RCTalk! 🚀

    Join the #1 RC community where hobbyists connect, share, and get expert advice on RC cars, trucks, boats, drones, and more!

    • ✓ Friendly & passionate RC enthusiasts
    • ✓ RC tips & troubleshooting
    • ✓ Buy, sell & trade RC gear
    • ✓ Share builds & upgrades

wierd problem-please help

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.
P

person123

RCTalk Racer
Messages
90
Reaction score
0
Points
0
Location
Oak Harbor
RC Driving Style
  1. Bashing
Okay, I have a savage x ss that had MAJOR half tank lean problems, and I got the new era OFNA tank mod which completely fixed my problem. I've run it about 4-5 times since the mod and had no problems. Yesterday, it was about 50 degrees F outside (as opposed to high 50's to mid 60's on the other runs) and the truck seemed to be running fine. I thought that I would have to tune the high and low speed needles down (rich) to compensate for the higher oxygen content in the colder air. My high speed needle was fine, but my low speed needle actually seemed rich. There was a delay in the acceleration, so I leaned it just a little bit. Then on the second tank, when I refueled, I spilled a little fuel on the outside of the tank and on the engine, but not a lot. I wiped it up, and when I brought it in after about 4 min to check the temp, there was a ton of dirt/fuel on the outside of the tank and under the rim of the lid around the seal. Again I wiped as much off as I could, and the same thing happened again, and again. I also noticed that, while there was still blue smoke and temps in the 210 to 230 F range, that the low speed and idle were ACTING lean. There was too much blue smoke to mean that they were actually lean.

sorry about the long explanation; I didn't want to leave anything out

thanks ahead of time
 
You shouldn't have to re tune the LSN unless you're switching fuel. Only the HSN needs to be tweaked for outside temp and humidity changes. If it tends to 'wander' at idle, it would be a sign of an air leak. Other than that, if the temp is good and you're getting blue smoke, you should be fine.
As far as the dirt goes, it's the oil residue left from the fuel that it's sticking too.
 
Rolex said:
You shouldn't have to re tune the LSN unless you're switching fuel. Only the HSN needs to be tweaked for outside temp and humidity changes. If it tends to 'wander' at idle, it would be a sign of an air leak. Other than that, if the temp is good and you're getting blue smoke, you should be fine.
As far as the dirt goes, it's the oil residue left from the fuel that it's sticking too.
Click to expand...

Yes, that is what I thought too. When I first got the new tank, I had to lean the lsn about 3/4 turn, and I've had to tweak it and the idle every time I drive it, but it always runs great after a little tweaking. This time, it was showing signs of running lean, but there was plenty of blue smoke and the temp was a little lower than I usually run it at. Like I said, the hsn was pretty much fine, but I think I did richen it a little. Let me know what you think
 
Normally, you don't need to change your LSN and idle settings once they are good. It may be that you're adjusting them rather than waiting for the engine to warm up to proper running temp.
If it runs good when it's warmed up, but you still need to tweak the LSN and idle when it's cold, you most likely have a leak in the system.
 
If it is an air leak, it must be in the tank. The fuel lines are new, and the tank seems like it is leaking a little fuel like I said earlier. I had to screw the little fuel inlets into the tank, and they didn't screw in with much resistance. The threads are closely spaced and very small/short, and the only seal they have is a little washer. I can't tighten them down enough to compress the washer a little because I am afraid I will strip the threads in the tank. The spring on the lid is also a little weak. The weird thing is that it ran fine for about 8 tanks before yesterday.

Any ideas on what I should do? I'm thinking that I will plug off the openings to the tank, clean it off with wd-40 or motor spray, and then pressurize it and put drops of soap and water in the different spots where the leak could be to try to find a leak. Thoughts?
 
Last edited:
My truck is pretty new so I think that the header gasket is fine, will check though. The mess is actually on the tank near the fuel outlet.

It is possible, like rolex said earlier, that I went to tuning the engine too early and it was indeed running a little lean when the engine had warmed up more. I am used to my rc10gt with a .12 that warms up in about a minute. I think that there is still something wierd with the tank because the oily dirt kept re-appearing in large quantities after I would wipe it off. I think that I'll clean the tank, and run it again later today or tommorow if I get a chance. I'll keep you posted, and thanks for the help.
 
Ah. Do you have a link to the new era kit you have? You could just try and replace the tank itself. If it's the tank I used, they would split on you right under the tab that the mounting bolt goes through if you tightened it a hair too much.

I think new era's use this:
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXBM24&P=7
 
ALL your tuning should be done when the engine is up to running temp. If it takes a little idling and rolling around to get it there, that's normal. If you want it to rip off the line as soon as you start it, you'll be running too lean when it warms up.
 
Mine split at the seam and I didn't notice it at first. But I did notice there was fuel all over the back of the tank and I thought it was the cap. It wasn't.
 
crud...ok thanks for the info. That sounds exactly like the problem. I didn't think to put some sort of rubber damper like a shock o ring under the tabs when I installed it. I don't know if that would help though. Is there a way to re-seal the tank, like with CA glue or something?
 
In a pinch you can use a soldering iron and melt the crack together, just make sure all the fuel is out and you don't just burn a hole through it.

Hold the talk under water and blow into the pressure line with the other fuel line pinched out of the water and see where the bubbles are coming from the tank at.
 
scoobydoo2u said:
In a pinch you can use a soldering iron and melt the crack together, just make sure all the fuel is out and you don't just burn a hole through it.

Hold the talk under water and blow into the pressure line with the other fuel line pinched out of the water and see where the bubbles are coming from the tank at.
Click to expand...

Cool, thanks for the soldering iron tip. Will it be easier to see where the leak is if I test it like you said, or if I put a drop of soap and water on the different possible places?
 
Probably just like I said, that way you can see if there are multiple leaks all at one time.

The soap and water would work as well.
 
Ok, I tried the soap and water, then the fully submerged deal, and I didn't see any sign of an air leak. I actually had to hold down the lid or the lid would pop up. I guess that is good news, but now I don't know what the deal is. I'll run it again when the weather gets better hopefully later this week. Thanks for the help and I'll keep everyone posted.
 
Last edited:
Sounds like you've maybe overspring the lid spring? (opening too far to fill it)
Or the spring is just junk.

$10 buys a new tank. I'd just order one up and put your current problem behind you, then move on to the next one if there is one.
 
I haven't run it yet, but I think that I just made a tuning error, and associated that with the dirt on the tank that kept re-appearing. I forgot if I already mensioned it, but I did spill a little fuel on the outside of the tank before I started the truck, and it is possible that I didn't get all of the fuel wiped off.

As for the spring, I think that I probably did over-open the lid a few times but the spring was never very strong. Is there a way to increase the tension on the lid? I don't see replacement lid springs available much less stronger ones.
 

RC Builds

Back
Top