2001 efi turz 250hp lx surging (posted in the spring)

[bernieb]

Engine has been in dry storage since early april and now for some gulf fishing (i hope). Took the advice from the five star rated mechanic here, Rod......something (Gotcha). Anyway periodically around 4000 rpm the surging kicks in ,not uniform, sometimes it ran great on a trial run close to shore but just not right. This week i've cleaned out main tank stainless steel with bleach and water, got bone dry and took the guts out of the anti-syphon valve which was clean.Checked all six micro tiny filters in fuel injectors and appeared clean,also checked vst filter that was clean,screen in pressure regulator was clean. One item I'm not sure of.....the big black float in vst ,when I tighened it down the pin raises up on the other side,the yamma site shows two screws ,but i see no hole for the second screw,i'm thinking my float may be hanging up,but when we tested it on the water we had a steady 35psi during surging,and near 0 pressure on tee fitting prior to low lift pumps. The red ring filter has never been changed but looks clean. Anything else before another water test? thanks bernie

 

[rodbolt]

Re: 2001 efi turz 250hp lx surging (posted in the spring)

carefully check the O2 sensor voltage output, 4000 RPM is the danger level, if its a bogus reading the ECU will react and it can burn a piston, also double check those low pressure pumps, min output is about 3 PSI. normally a bad lift pump will make it idle funny and you will see a lot of fuel "rainbows" in the water at idle.
and BTW, 5 star is a 20 min video, master tech takes 20 minutes more

 

[bernieb]

Re: 2001 efi turz 250hp lx surging (posted in the spring)

I have really great news,the engine runs perfect. Sorry i failed to mentioned that the 02 sensor checked out okay and the three lift pumps were changed (your advice) but due to your advice that the problem was fuel related ,i checked every item and the culprit was ....somewhere between two yamaha dealerships and my two cents in the past two seasons of overlooking the problem it was the black float in the vst tank that had the wrong head on the screw that held the pivit pin that the float depended on. The screw that was there was the same size and head size that held the two halves of the vst tank.It was causing the pivit pin to ****-up on the other side I guess jamming the float so when the demand for more gas ,it couldn't do it, so it really needs a panhead type screw. Anyway thanks rodbolt for keeping me on track. And thanks I-boats,so shop their parts for providing this site..