Need Help with my fx400

[jniebuhr]

This winter before going to glamis I dropped a new piston in the motor and when I reinstalled everything the motor fires right up and idles great but when you start giving it any throttle above about 5000 rpm it starts surging and back firing and and continues to get worse until it dies but they it will fire right up again seems like timing but that doesn't make sense and I have since replaced the TPS with no luck any help would be greatly appreciated thanks

[SlOoT]

Swollen o-rings in the quik-dissconnnects in the fuel tank could be a cause.
Because of that the injectors will not get enough fuel.

I recommend getting the upgrade kit from Canniboomer.

[thedeatons]

So, as a troubleshooting procedure before you go buying things, you may want to get a full gas can, and hook up a rubber line to the fuel pump inlet (from the tank), sucking fuel up from the gas can. Just remember to route the fuel return line back into the same gas can, or a different one, so you don't overfill your tank.

Using this method you will be sucking fuel through straight hoses only, with no disconnects inline, and it only costs you a couple dollars for fuel lines to and from the gas can.

If this solves your problem, then I would definitely recommend calling Canniboomer (Dave) and getting his tank upgrade kit. The easiest way is to send him your tank and he will install it for you. Full flow quick disconnects with a petcock valve and Viton o-rings for no swelling later on.

Don't forget to run a 5 ft return line to the tank (from the right side fuel injector). This way you can refuel yer buddies if they run out of gas. Just turn your quad on and it will pump fuel out of this hose (after you disconnect it and aim it into their tank of course!).

Yet another cool Dale thing!

[jniebuhr]

QUOTE (thedeatons @ Apr 11 2008, 03:19 PM) <{POST_SNAPBACK}>

So, as a troubleshooting procedure before you go buying things, you may want to get a full gas can, and hook up a rubber line to the fuel pump inlet (from the tank), sucking fuel up from the gas can. Just remember to route the fuel return line back into the same gas can, or a different one, so you don't overfill your tank.

Using this method you will be sucking fuel through straight hoses only, with no disconnects inline, and it only costs you a couple dollars for fuel lines to and from the gas can.

If this solves your problem, then I would definitely recommend calling Canniboomer (Dave) and getting his tank upgrade kit. The easiest way is to send him your tank and he will install it for you. Full flow quick disconnects with a petcock valve and Viton o-rings for no swelling later on.

Don't forget to run a 5 ft return line to the tank (from the right side fuel injector). This way you can refuel yer buddies if they run out of gas. Just turn your quad on and it will pump fuel out of this hose (after you disconnect it and aim it into their tank of course!).

Yet another cool Dale thing!

Thanks for the help I will try that on saturday Talked to dave today and am getting things set up for the tank upgrade! Thanks again for the help guys

[jniebuhr]

So I try the quick disconnect bypass and It is a little better then before but is still surging and back firing alot at higher rpms should I look at replacing the fuel injectors? or If anyone has any other ideas that would be great thanks

[MyCannibal]

sounds like u need a throttle cal and idle adjustment...

[jniebuhr]

That means Im going to have to break down and by a D&M Kit is that all I need to ajust that

[ABM-CANNIBAL]

A D&M will not help you if you have a FX400. You will have to try and find a Mil Tool because you have a 500 ecm.

[MyCannibal]

yep Mil tool...

[wistech]

Check your flywheel for spinning and the keyway.