Fuel pressure problem.

[easy rider]

I built a big block tmaxx. Extended the chassis with a rcrnew kit. Dropped an alpha 5 port .28 in it. It’s a screamer. But, I’m having problems once I het below half a tank. When I’m ripping it around it runs great. But, I’ve got to keep fuel in the tank. Or it starts getting air in the fuel line and starts “missing”. At a tad less than 1/2 a tank. Everytime.

As it gets lower in fuel, it gets more persistent. I can fill it up, and raise Cain till it gets to about a 1/3 a tank. Then it starts again.


Please understand it is not a tuning issue. I’ve changed gaskets, springs, fuel lines. And, it doesn’t cut out if running a straight line wot. But, as it gets low, the sloshing around causes air bubbles in my line.

I’m running a short pressure line. And probably a 9-10” pressurized intake line from the tank.

I’m figuring a longer pressurized fuel line might fix it. Or, an inline filter might help. Maybe not but, I’m thinking it would. It’s a stock tmaxx 3.3 tank.

If I baby it once it starts getting low. By not whipping it around or running in rough terrain, I get about 7 minutes, per tank. My guess it if I didn’t have to start making my turns wide and slower to prevent the miss, I’d get 6:30 a tank.


It’s a fun truck but, deserves to have this fixed. I’d live to hear from you guys what you think would prevent this. Different tank, longer lines, filter, in line bulb,etc…???

 

[PonkyKong]

Is it running super smokey?

 

[watertrucker]

I had a similar issue with my TMaxx a few years back. It would run good for a bit and then start bogging and starving for fuel. What I finally found was the the cap on the fuel tank wasn’t sealing properly. I just tightened the screw under the cap to improve seal and that fixed it. Hope this helps

 

[CertifiedMike]

Look into the location of the fuel pick up in the tank.
I have seen this before.

Lets see if my memory is good. I think @ohsnap had the fix for this.

 

[WRM]

I had a similar issue with my TMaxx a few years back. It would run good for a bit and then start bogging and starving for fuel. What I finally found was the the cap on the fuel tank wasn’t sealing properly. I just tightened the screw under the cap to improve seal and that fixed it. Hope this helps

Agreed!

Since you changed the lines, this was my second thought. My third thought was to make sure the tank clunk is functioning properly (goes to top when you turn it over), as Mike suggested. It should be able to handle some fuel sloshing around and bubbles in the line.

 

[easy rider]

Is it running super smokey?

Nope.

 

[easy rider]

Agreed!

Since you changed the lines, this was my second thought. My third thought was to make sure the tank clunk is functioning properly (goes to top when you turn it over), as Mike suggested. It should be able to handle some fuel sloshing around and bubbles in the line.

It has no clunk in the tank.

 

[easy rider]

Agreed!

Since you changed the lines, this was my second thought. My third thought was to make sure the tank clunk is functioning properly (goes to top when you turn it over), as Mike suggested. It should be able to handle some fuel sloshing around and bubbles in the line.

It should but, it’s not. lol

 

[ohsnap]

Lets see if my memory is good. I think @ohsnap had the fix for this.

While I had a similar problem, the issue (and fix) that I had with my Losi doesn't align with Easy's situation.
Mine was clunk induced.

Easy - Has this situation come about once you installed the .28 and are you still using the stock tank?
Given the paths that you've already been down, I would try installing a new tank to see how it responds.

Perhaps the sintered filter is slightly clogged towards the bottom and once the fuel gets low enough, it starts sucking more air than fuel once the top of the sintered filter is exposed, or maybe the current tank can't keep up with the .28's demands?
Try installing a smaller engine to see if the issue repeats itself?
Totally guessing here...

 

[PonkyKong]

Nope.

I suspect it's leaning. Air leak or fuel restriction.

 

[easy rider]

It’s a new tank. First tank I had on there was new as well. Stock tmaxx tank 125ml.

I have since installed longer pressure and fuel lines and a Kyosho inline filter.


I haven’t had a chance to run it yet. But, when loose from the carb it now shoots fuel a good couple feet when priming. So, I plugged it back in and fired it up. That’s as far as I’ve been.


I understand everyone’s advice as it leaning out. However, it isn’t leaning out. There’s no fuel in the line is the problem. Caused by what I do t know.


As far as I can tell this has helped currently. Time will tell. I’ll update as soon as I get to run.

It’s done it with 2 motors as well. Both broke in on this platform. Both .28’s. First was a modified dynamite mach 28. Brutal motor for sure. I was hoping the issue was the tank could t keep up with the fuel demands due to being modified. Nope. Same issue with the alpha 28.

New tanks. New lines. Currently I increased both line lengths to about 12”. And added a filter to the fuel line. If this doesn’t fix it all that’s left is changing to a different tank. I’m thinking a buggy tank. Less moving stuff around to get it to fit.

 

[easy rider]

Current setup. Always easier to see what’s been talked about. Sorry, should have put this up first. Nothing like asking for help but making it harder. lol