Vmax 225 ox66

[pistonguy]

Hi guys

i have a 2001 vmax ox66 225 which is giving me surging problems and i can’t seem to figure out what is causing it. I am not a mechanic by no means and i was wondering if anyone on here could help me out.

Things i have done are
1. installed 3 new lp pumps and gaskets
2. cleaned O2 sensor. Wasn’t much carbon build up on it but i cleaned it anyways.
3. Cleaned the vst filter, regulator filter and water/seperator filter
4. Cleaned the oil bottle on the side of the engine
5. checked fuel pressure which was ready 38 psi before starting and then it would hold 35 psi even when the motor would surge and almost come to idle by itself and then pick the rpm’s back up for a few seconds and drop them again.

any help would be appreciated. Thanks kevin

[99yam40]

if rail pressure holds even when it drops off RPM then check to see if timing and spark are holding,
then it is try new spark plugs and injector cleaning

[pistonguy]

Ok. Are you able to tell me how to check timing and spark. I had the injectors tested and cleaned a couple days ago and im still having the same issue

[panasonic]

Kevin,

Do yourself a big favor and buy the proper Yamaha manual for your engine. You can look the part number up in the very first posting on this site...go to the list of topics and right on the top highlight in yellow.

This site sells the manuals or you can get a PDF online from Yamaha.

I am sure have already spent more money on parts then what the manual will cost.

Good luck

[pistonguy]

I’m trying to find the pdf for the manual but I can’t find it

[panasonic]

I’m trying to find the pdf for the manual but I can’t find it

What is the exact model and Serial number from the data plate located on transom bracket?

[pistonguy]

Vx 225tlrz
66k L 304251S

[pistonguy]

Took the pulser coil and stator off and cleaned them up because there was a lot of corrosion and rust on them now the engines runs good.

thanks for the help guys

[99yam40]

thanks for coming back to let us know what fixed you motor.
testing ignition system as manual calls for probably would have shown a problem with the spark producing components

Spark and timing can be checked with an inductive timing light hooked to plug wires