This past summer my son was riding our Trail Boss and it started sputtering and eventually stalled out. We have not been able to get it to start since.

With that I did\checked the following:

1. Checked Spark plug (actually changed it as well). Appears to be ok. Old one was black and I beleive dry.
2. Drained all gas, refilled with new.
3. Checked all fuel lines from tank to on-off-res switch, then from switch to fuel pump and to carb. Gas appears to flow through the lines (see fuel pump comments below).
4. Checked Fuel filter. Seems to be ok.
5. Checked carb. Cleaned with carb cleaner. I went through it the best I could. But did not want to mess it up. So I did not unscrew everything (internally). Did not want to mess it up.

This brings me to the Fuel Pump, that the one hose lines go to (from on-off-res switch) and then 2 lines to the carb.

Not sure how this pump is suppose to work and as result may be the issue.

When attempting to start the machine, I see some fuel on the low side of the filter on the incoming line. However, it does NOT appear to pull/suck the gas through (when attempting to start). If I pull the 2 outgoing lines off the fuel pump or off the carb, no gas flows through... When turning over, I feel pull/suck off right side of carb (where one of the hoses connect) but not on left side (hose connects on left side, more on top of carb.

How does this fuel pump work? Does the carb activate it? Should fuel flow out if the outgoing hoses are disconnected?

Hope I am making sense of what I am trying to explain.

Am I on the right track? Any suggestions?

Thanks in advance.

Regards,

Sam







I have no idea what to check next. Somebody has to know something. My thanks to all in advance

 

You are making good sence of what you checked. Most leave alot of quetions to be asked. I "BELIEVE" the fuel pump works on engine crankcase pressure. The air pres. turns the fuel pump. I have never troubleshot one to know for sure. I traced a line one time from the engine to the pump. That is why I believe this is how it works! Also most people do not know that there is a kill switch on the throttle cable. It is under the throttle cover near the thumb controller. It is designed to kill the engine if the cable breaks. If the switch is faulty, you could be cranking it over with no spark. A spark check could eliminate this though. Does it fire on ether? That could tell alot.

 

i beleave the fuel pump works by vaccume from the crank to prime the the pump. first thing i would check is to make sure the petcock in the tank is working letting gas out then go to the pump. when you crank it over your getting any gas to the spark plug? did you try putting gas down the hole or squirt some in the carb to fire the engine. just a thought.

 

how about compression? does it have good or bad compression. Is it turning over?

 

Wasn't quite sure. I wonder what happened to the good old days of gravity feed.

 

Thanks for the feedback... Spark Plug does have good spark... Compression seems be fine as well.

I did learn that one of the hose lines off the fuel pump is a vacuum line, as confirmed by replies in this thread. So, I will check and see when it is hooked up that it spits out gas on the other hose line. If not, I believe that this where my issue is. If it does, fuel pump is good and I move back to the carb.

I will try the suggestion of putting gas in carb\spark plug and see if it turns over.

I will not be able to get to this until Saturday. I will report my findings then.

Thanks for the replies. They are very much appreciated.

Sam