Hey Everyone,
I have a 150cc Trailmaster Challenger go-kart/ATV that I've been having starting issues with for several years. Initially when I first got the go-kart it started fine and ran perfect. I upgraded the exhaust and the air filter intake to a UNI setup. I also adjusted the jets in the carburetor. Again everything ran great for the first 2yr. Then the starting issues began. Below is the list of things I've done but first a little description on what the go-kart is doing now. It will not start with just choke and turning the key. I'll let it turn over for a minute or two with not even a sputter. This is where it gets interesting. To me on the surface this appears to be a fuel supply issue. However if I use some starting fluid prayed into the carb it starts right up and idles smooth and is responsive to stomping on the throttle. So thats where I'm stuck because if it was a fuel supply issue it would be starved when driving and hitting the throttle.
I checked and replaced the spark plug (checked for spark and that looks good) after idling for a while the spark plug color is a nice tan
changed fuel filter
replaced the vacuum fuel pump
replaced the battery
swapped out the electronic fuel enricher for a manual choke
checked for compression (using thumb on spark plug hole)
replaced the entire carburetor
Checked intake boot for cracks
checked the kill switch
changed the CDI
checked the solenoid
Replaced the coil and plug wire
Drained the fuel tank and replaced with new fuel
I've tried everything basically. The only thing I haven't done is adjusted the valves. But I don't see how the valves could be the issue but maybe I'm missing something. I'm waiting right now on a check valve I ordered to install on the fuel line near the inflow to the carburetor. My theory is the fuel is being siphoned back to the fuel tank (when the engine is off) which is located below the seats (lower than the engine) so when starting the fuel pump which is vacuum controlled off the intake is trying to pull fuel up from the tank to the carburetor and its just really weak when the vacuum is only based on the starter turning over the engine at lower RPM's. If this is true though I can't explain why it worked fine the first year or so when we got it brand new. I should also note that it hasn't been ridden much so total engine where and tear is very low. Maybe only 100 miles or so total. I've googled every thread I can but no one has specifically the same situation I have where once the engine starts it runs great. It just requires starting fluid every time which is not great for the engine as I understand it.
Again any help is much appreciated. This could totally be a simple issue that I just cant see.
Thanks,
Derek
I have a 150cc Trailmaster Challenger go-kart/ATV that I've been having starting issues with for several years. Initially when I first got the go-kart it started fine and ran perfect. I upgraded the exhaust and the air filter intake to a UNI setup. I also adjusted the jets in the carburetor. Again everything ran great for the first 2yr. Then the starting issues began. Below is the list of things I've done but first a little description on what the go-kart is doing now. It will not start with just choke and turning the key. I'll let it turn over for a minute or two with not even a sputter. This is where it gets interesting. To me on the surface this appears to be a fuel supply issue. However if I use some starting fluid prayed into the carb it starts right up and idles smooth and is responsive to stomping on the throttle. So thats where I'm stuck because if it was a fuel supply issue it would be starved when driving and hitting the throttle.
I checked and replaced the spark plug (checked for spark and that looks good) after idling for a while the spark plug color is a nice tan
changed fuel filter
replaced the vacuum fuel pump
replaced the battery
swapped out the electronic fuel enricher for a manual choke
checked for compression (using thumb on spark plug hole)
replaced the entire carburetor
Checked intake boot for cracks
checked the kill switch
changed the CDI
checked the solenoid
Replaced the coil and plug wire
Drained the fuel tank and replaced with new fuel
I've tried everything basically. The only thing I haven't done is adjusted the valves. But I don't see how the valves could be the issue but maybe I'm missing something. I'm waiting right now on a check valve I ordered to install on the fuel line near the inflow to the carburetor. My theory is the fuel is being siphoned back to the fuel tank (when the engine is off) which is located below the seats (lower than the engine) so when starting the fuel pump which is vacuum controlled off the intake is trying to pull fuel up from the tank to the carburetor and its just really weak when the vacuum is only based on the starter turning over the engine at lower RPM's. If this is true though I can't explain why it worked fine the first year or so when we got it brand new. I should also note that it hasn't been ridden much so total engine where and tear is very low. Maybe only 100 miles or so total. I've googled every thread I can but no one has specifically the same situation I have where once the engine starts it runs great. It just requires starting fluid every time which is not great for the engine as I understand it.
Again any help is much appreciated. This could totally be a simple issue that I just cant see.
Thanks,
Derek
