Suzuki DF50 stalls after 100yds running

[patpat]

My Suzuki DF50 runs great most of the time. However, very often after being run for a mile or so, shutting down for an hour or so then restarting it will start great, get up on plane quickly, then shut off after about 100 yds. No apparent reason. The primer bulb will be soft. I pump the bulb till firm and it will run fine till the next time it sits for awhile. Just had the 200 hr service performed. Engine was said to be working perfectly. This a problem that has appeared and disappeared several times before. Plugs were changed a few months ago. No change in the occurrence of the problem. Some days no problem. Some days it happens every time I sit a while and restart. Using high test gas and Yamaha gas additive. Ethanol free gas when I can get it. I put a clear plastic tube in my gas line and observed it for air bubbles. Did not see and air bubbles. (At home on muffs at 4k rpm) Thanks for your attention. patpat

[keakar]

next time it happens check the gas cap right away to see if it has formed a vaccum, it may be a faulty tank vent

[patpat]

Gas cap is always vented. I never close the vent. No vacuum. Other posts talk about vapor lock on larger engines. Could this be the problem?

[keakar]

well just because its set to be open doesnt mean it cant be internally clogged

next time it happens just unscrew the cap and see if its sucking air so you can rule it out.

vapor lock can be from a faulty tank vent or it can happen to a carburated engine if the carb vent gets blocked

[patpat]

I will check it next time out. Same problem with main and spare tanks so I doubt it but will try anything. Thanks again Pat

[keakar]

i would think so but the soft bulb indicates loss of fuel flow or air entering the fuel line. enough air bubbles in the line can cause it to starve for fuel and act the way you described.

if you can find a way to seal off both ends of the fuel line and pressurize it with air you can use soap bubbles to check for leaks or at least see if it looses pressure telling you to replace the fuel lines.

you can test the engine by using a portable tank with its own hose to test if it still happens, if not its a fuel line problem, if so its something under the cover. the spare tank may not change anything if its using the same fuel lines as the regular tank.

[captfrankie]

I've experienced the same problem a number of times over the years. Most recently this past weekend. I had an extremely hard time getting it restarted.That's why I'm here. My engine is a DF225. It is spring when it happens. Never Summer Fall or Winter. I was told it was water in the fuel. I will change my fuel/water seperator filter fill the tank and put some water dissipator.

[kevmat200]

Ive been having the same problem with my suzuki df250 they replaced everthing in the fuel system didn't solve the problem, so they replaced the motor with df250 ss, been running great till this last weekend and it stalled 2 times, only 40 hrs . now they are telling me its a vapor lock issue with suzuki and their fix is to add an additional fuel pump. anyone heard of this fix?