1999 250 yamaha

[rblacktips]

motor still surging .changed the thermastats ,new fuel pump kits were installed i have taken off the o2 sensor and cleaned it didnt look all that bad.when i brought it to the shop they changed the fuel pump kits one of the diaphrams were cracked they say the cleand the fuel injecter but when i whent to take it gor a test run still doing the same thing.surging wont get up and when it does it will run and then bog and run and bog its getting plenty of fuel even the mechanic doesnt know what top think.so any advice would be greatly help thanks

[jlandgraf]

this may sound strange, but have you checked your battery terminal connections.... not sure of the exact nature of your problem, but my engine was bogging down repeatedly a while back and it was due to a loose negative battery wire. it would run fine, fall on its face, run fine, fall on its face, run fine etc. very erratic. if i'm way off, sorry. i just remember thinking how easy the fix was after i changed all filters, plugs, etc. good luck,

jeffery

[robert graham]

surging is usually caused by a fuel delivery issue. Check fuel system starting at tank pick-up, tank fittings, primer bulb, quick disconnect on motor, filter, pump. Probably a bad check valve in the primer bulb or fuel pump or an air leak possibly at quick disconnect. Check it all out. Good Luck!

[rblacktips]

250 yamaha

yea im at a loss right know .its still in the shop mechanic got to see first hand form him self what i was explaining to him he is looking in to seing if it could be one of the sencors . thats why i been trying to get as much info from the forum cause i have and the shop has already pretty much whent through the whole fuel system cause thats what the mech thought also just getting frustrated paid like 800.00 already and we still at square one so everything and any advice is trueley a help thanks

[DMSOUTH]

Try running on a portable tank with fresh fuel, different hose and different bulb first. If it runs good on this, then the trouble is in the tank or line. If it still runs like crap, time to start troubleshooting engine.

[jf123]

Install the diagnositc tool. (Winky Blink) and check for any codes. Besides that a multimeter and start testing inputs and outputs when the problem occurs. Check fuel pressure both PSI and vacuum. Plenty of fuel means nothing without actual readings.