tonyp34 Posted January 15, 2010 Share Posted January 15, 2010 heard about this lean tank problem on savage xl how do you fix this any pics please thanks Quote Link to comment Share on other sites More sharing options...
EazyDUz Posted January 15, 2010 Share Posted January 15, 2010 The only fix which works and doesnt look ridiculous (like the extra tank mod) is as follows: Loosen the fuel nipple on the carb side so it points towards the fuel tank, tighten it again. Now cut the exhaust pressure line so its just long enough to reach the fuel tank. Now remove the fuel line and cut it so its just long enough to go from the fuel tank, round the front of the engine (as apposed to round the back near the rotostart), past the air filter and plug it in to the newly positioned fuel nipple. The theory is this: A long pressure line is restrictive because when the fuel tank has not much fuel in it, it takes longer for the tank to pressurize with a long line, so a shoter line allows it to pressurize more quickly, therefore pushing the fuel into the carb more efficiently, which therefore richens the engine. As for the shoter fuel line, there isnt much scientific explanation otther than in theory a longer fuel line creates more friction between the fuel and the line therefore it takes more pressure to push the fuel through a long line. Also a longer line holds more fuel and therefore needs more pressure to push more fuel. So a shorter line fixes this. I found this mod on another site and its cleared even the worst cases of half tank lean, ive done the mod myself but havnt had a chance to test it due to the weather among other things. Hope that helps. Quote Link to comment Share on other sites More sharing options...
Mr Terminator Posted January 15, 2010 Share Posted January 15, 2010 Hi mate,this is a perfect solution that I used to do with the Genesis trucks as they suffered from the same problem.Because they have such big fuel tanks and they're on the side of the truck,they get gradually worse as the fuel goes down,it was evident with the Genesis at around half a tank,the problem is because the tanks aren't baffled well enough to have them on the side of the truck. Get the filter in the link i've posted,take out the internal stone filter and disgard it,the filter has an arrow on it,place the filter in between the exhaust pressue line,just cut it in two,make sure the arrow is pointing towards the fuel tank,the filter is a one way valve aswell for priming the fuel tank in its normal use,this filter in this role allows air in the tank from the exhaust but doesnt allow it back this forces the fuel into the carb and gives a constant pressure in the tank. Simple and effective fix for this problem that works with any side tanked model that suffers with mid tank leaning.... The filter in question... http://www.modelsport.co.uk/?CallFunction=ShowSpecification&ItemID=17246 Quote Link to comment Share on other sites More sharing options...
EazyDUz Posted January 15, 2010 Share Posted January 15, 2010 More info for the completely free fix here: http://www.rcuniverse.com/forum/m_7538776/mpage_1/key_/tm.htm Along with actual users comments and a guy who did an experiment on different lengths of line Quote Link to comment Share on other sites More sharing options...
PyRo Posted January 15, 2010 Share Posted January 15, 2010 Hmm gonna give the pipe shortening method a bash, thanks for the tip. PyRo Quote Link to comment Share on other sites More sharing options...
tonyp34 Posted January 15, 2010 Author Share Posted January 15, 2010 thanks for your help Quote Link to comment Share on other sites More sharing options...
gazb1488 Posted January 15, 2010 Share Posted January 15, 2010 im with mr teminator, i did exactly the same thing and it works a treat. and its very reliable. well worth the Quote Link to comment Share on other sites More sharing options...
koiboy Posted January 16, 2010 Share Posted January 16, 2010 Hi mate,this is a perfect solution that I used to do with the Genesis trucks as they suffered from the same problem.Because they have such big fuel tanks and they're on the side of the truck,they get gradually worse as the fuel goes down,it was evident with the Genesis at around half a tank,the problem is because the tanks aren't baffled well enough to have them on the side of the truck. Get the filter in the link i've posted,take out the internal stone filter and disgard it,the filter has an arrow on it,place the filter in between the exhaust pressue line,just cut it in two,make sure the arrow is pointing towards the fuel tank,the filter is a one way valve aswell for priming the fuel tank in its normal use,this filter in this role allows air in the tank from the exhaust but doesnt allow it back this forces the fuel into the carb and gives a constant pressure in the tank. Simple and effective fix for this problem that works with any side tanked model that suffers with mid tank leaning.... The filter in question... http://www.modelspor...on&ItemID=17246 I have got some oneway valves spare from my fish tank. Would these work? If not a priming bulb is on my next ms order Top cheap Mod Mr T definatly going to try this one on my savage Quote Link to comment Share on other sites More sharing options...
Mr Terminator Posted January 16, 2010 Share Posted January 16, 2010 I think the fish tank valves may be a little susceptable to heat but the theory and design is the same,just different materials... Quote Link to comment Share on other sites More sharing options...
EazyDUz Posted January 18, 2010 Share Posted January 18, 2010 So did either method work mate? If so which one was best? I have yet to try the shortened lines but might also buy a filter as well. Quote Link to comment Share on other sites More sharing options...
tonyp34 Posted January 18, 2010 Author Share Posted January 18, 2010 So did either method work mate? If so which one was best? I have yet to try the shortened lines but might also buy a filter as well. i shortened the fuel lines but hard to tell at the moment as i am still only breaking it in .Is it really noticeable the lean tank problem mate ? Quote Link to comment Share on other sites More sharing options...
EazyDUz Posted January 18, 2010 Share Posted January 18, 2010 Was for me last time i used it. Though its cold now so cars run richer anyway. But in the summer its bad. I like my Savage to wheelie on command and when the tank gets too lean it wont. Also it used to cut out at half tank as well. I cant tell if the shorter lines have fixed it until its warmer outside, then ill buy Term's mod if required. Quote Link to comment Share on other sites More sharing options...
EazyDUz Posted January 19, 2010 Share Posted January 19, 2010 Wouldnt the valve idea cause problems? For one you have to tune the engine when the tank is fully pressurized, so when you try and start the car from cold wouldnt it cause problems as the engine has been tuned for a highly pressurised tank? Quote Link to comment Share on other sites More sharing options...
martin34 Posted February 20, 2010 Share Posted February 20, 2010 I am going to get one of them filters and give it a go on my XL .The fuel line shortening sounds worth a go aswell but the only thing that puts me off of that is with the truck upside down it will conk out before i can get to it . Quote Link to comment Share on other sites More sharing options...
paul4be Posted February 20, 2010 Share Posted February 20, 2010 Some interesting thoughts. What happens to the fueling with a one way valve if you run at w.o.t. and then lift off, will the tank be quite highly pressurised and overfuel the motor until the pressure drops again? I hope that question makes sense, it does in my head! Quote Link to comment Share on other sites More sharing options...
EazyDUz Posted February 20, 2010 Share Posted February 20, 2010 I am going to get one of them filters and give it a go on my XL .The fuel line shortening sounds worth a go aswell but the only thing that puts me off of that is with the truck upside down it will conk out before i can get to it . Simple cure for that is to improve your driving skills. I get tired of hearing about people complaining about engines stalling when the car is upside down. Quote Link to comment Share on other sites More sharing options...
martin34 Posted February 21, 2010 Share Posted February 21, 2010 More info for the completely free fix here: http://www.rcuniverse.com/forum/m_7538776/mpage_1/key_/tm.htm Along with actual users comments and a guy who did an experiment on different lengths of line I just read through the thread linked to and i am going to try the line shortening mod instead of the filter.I have the fuel line in the tank mod at the mo but it is a pain to prime the engine as i prime by blowing through the pressure line but always end up with a mouthfull of fuel .Its free so i will try it . Quote Link to comment Share on other sites More sharing options...
dmeader Posted February 21, 2010 Share Posted February 21, 2010 Sorry if this has been mentioned just scanned over this thread in a spare moment. If its that bad then have you thought about the mid tank mod. As I understand part of the problem relates to the shape of the tank. Savages are really modable wth parts and ideas a plnety. Also if you not 100% familiar with the truck it makes good practice. Quote Link to comment Share on other sites More sharing options...
locky Posted August 18, 2014 Share Posted August 18, 2014 Old thread but trying to find fix for half tank lean and came across this idea of fitting one way valve in pressure line as described, but the link to the part is dead. So hoping someone can confirm that this valve is the one that works......http://www.modelsport.co.uk/fastrax-fuel-filter-with-priming-bulb/rc-car-products/17246 Quote Link to comment Share on other sites More sharing options...
Ian w Posted August 18, 2014 Share Posted August 18, 2014 (edited) Yeah I picked this tip up from Mr. Terminator and all my Savages have it and it works well that is the right link. Make sure you have the arrow on the valve pointing towards the fuel tank.So the pressure is held in the tank. Edited August 18, 2014 by Ian w Quote Link to comment Share on other sites More sharing options...
locky Posted August 18, 2014 Share Posted August 18, 2014 Yeah I picked this tip up from Mr. Terminator and all my Savages have it and it works well that is the right link. Make sure you have the arrow on the valve pointing towards the fuel tank.So the pressure is held in the tank. Cheers, so is it easy to remove the filter, how do you actually do it? My last mod to prevent half tank lean was a header tank, but this was pain to fill. Quote Link to comment Share on other sites More sharing options...
Ian w Posted August 18, 2014 Share Posted August 18, 2014 I think you can see that Quote Link to comment Share on other sites More sharing options...
locky Posted August 28, 2014 Share Posted August 28, 2014 Been using the one way vale in the pressure line for a few weeks now. I,m not convinced it solves the half tank lean problem. But the engine wouldnt start today and found that the one way valve had stuck preventing pressure getting to the tank. Once cleaned it was working again. Quote Link to comment Share on other sites More sharing options...
RCbutcher Posted August 28, 2014 Share Posted August 28, 2014 Isn't an easy way to just loop the fuel line like traxxas revos. It apparently makes it help keep sucking up the fuel having 2 loops halfway into the line. Quote Link to comment Share on other sites More sharing options...
Nitroholic Posted August 29, 2014 Share Posted August 29, 2014 Won;t help with a Savage .... the problem in the Savvy is the shape of the tank and the way it pressurises. Most of the fixes are aimed at upping hte pressure a bit so that the pressure changes are not as noticable, so you can tune it to a constant fuel feed rate. Best solution I found was to mid-tank mod mine. Fit a tank with a constant cross section and the problem goes away. It's fairly drastic though.... I prefer not to use inline primer bulbs with one way valves as it provides potential air leaks. You have a join in the pipe for starters, and I have had primer bulbs before that split losing pressure. It's a simple and cheap cure.... just keep an eye on your fuel lines and check the bulb for splits. Quote Link to comment Share on other sites More sharing options...
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