Other Powersports, Offroad, and All Terrain Vehicles Forums

Brilliant, cheers, there is a good spark so it sounds like I have either a broken/poor live or a dodgy earth so hunting for that will be tomorrow's task 👍

The fan gets switched on when the oil temperature gets high. The fuel pump gets turned on when you first turn the key but then switches off unless it's getting a pulse from the cdi. The pulse from the cdi is the same pulse that fires the ignition coil, so if you have spark, you have the required pulse to operate the fuel pump relay, you just need to ensure it's getting to the pump control relay. When wires have no continuity, or have high resistance, it's almost right at the end of the wire where it crimps into the metal terminal, it either corrodes or breaks the wires inside the insulation. Wires do sometimes break if they have been chafing for a long time on something and worn right through the electrical tape, insulation, and then the copper wire, but that's easy to spot by the frayed insulation.

On the contrary, you and everyone who have replied have been very helpful, I really appreciate it. That's really good advice, thank you. I will pay particular attention to the earthing and post any findings.👍

Thanks for sharing, looks like a fun time. Im getting a little old for that kind of riding but like watching it. 👍

As i recall the motor controller, a very expensive part and no aftermarkets available, is activated by the CDI, and it absolutly has to have a good ground to operaate correctly, including the fan, the controller itsself may be grounded through the CDI, not sure, i am having trouble relating what i know to yours because the one im more familar with didnt have a fuel pump. I think what you are doing stripping the wiring loom and checking is the best way to find it, you can throw expensive parts at it all day long and still may not get it. You have worked hard at it i havent been much help, but good luck.

Round three of the 2024 ATV Motocross National Championship (ATVMX) Series, an AMA National Championship, headed to Lizella, Georgia to provide yet another action packed weekend of ATVMX racing on the sands of the Echeconnee MX facility. View the full article

What you say makes perfect sense but I think I must still have enough fuel in the tank to allow it to gravity feed as I tried removing the pressure line and blew into it...still nothing!! I gave up yesterday after stripping the whole top end and the wiring loom. Fuel relay working on rpm makes sense but I don't know what activates the fan as I can't find a thermostat!! Will have another go later today......

Thanks, no, I haven't noticed any other problems. I have now stripped out the complete wiring loom and will now test each of the wires!!

Yeah it does sound like a bad switch, you can take them apart and clean them up, but for this level of inconsistency i would just replace it . Aftermarket ones are fairly cheap and i havent had any problems with them.

Bought a brand new sparkplug coil. It measured 1.6 Ohms. It was harder to start, backfired more and ran same as old one.