1985 Evinrude XP150 surging above 35mph

[NoZero]

When you rebuilt carbs, did you remove all orifices and clean passages/right size orifices in right holes/remove welch plugs for idle transition circuit and clean and install new welch plugs? Verify proper orifices? idle-34/mids-34/mains-58.5....early first year XP/GT 150's had a 1 3/8 carb. Check and see if they havent been swapped out. 1 3/8 stamped on the front lower right of the front of carb. Once we verify the fuel system, we can move on to other fun and exciting things,,,

^^ 2nd This.

[omcforever]

Post #38 and #39

[Bigcountry7704]

Yes I removed and cleaned everything and verified jet sizes. The only things I did not replace were the lead shot and the little silver caps that you seat with a punch as none of those were leaking.

[omcforever]

Yes I removed and cleaned everything and verified jet sizes. The only things I did not replace were the lead shot and the little silver caps that you seat with a punch as none of those were leaking.

The silver things are the idle transfer circuit covers. They do get clogged/debri in them. Removing them, cleaning is part of the job. I never mess with the lead shot. Fuel pressure test would be what I do next with link and sync(never answered if it had been done/by the manual). Once you are satisfied with fuel system and link and sync then move on to electrical trouble shooting by the manual. Also verify roller in on the throttle arm on the center carb that touches the linkage cam.

[omcforever]

OMC# 0330130

[Bigcountry7704]

Ok would the idle transfer circuit cause either the surging or the bogging down when trimmed up to load on the trailer?

[omcforever]

Ok would the idle transfer circuit cause either the surging or the bogging down when trimmed up to load on the trailer?

Could but doubt it. Just should be part of the rebuild process. What did you set the float height to? What did you set the float drop to? Did a link and sync ever get done per the OMC manual? Fuel pressure test? Plastic roller on center carb?

[omcforever]

Pull all 6 plugs and take a pic and post them up,,,,remember what cylinder they came out of. When I diagnose, I work with one system at a time. Trying to insure fuel system is ok. Fuel pressure test(have seen a bad fuel pulse pump cause this),,link and sync, plastic roller, ect are a part of getting to the end result/diagnosis especially since you bought it with this issue and have no clue what was done prior to you getting it..

[Bigcountry7704]

Ok, and link and sync has been done, I need to do the fuel pressure test.

[omcforever]

Ok, and link and sync has been done, I need to do the fuel pressure test.

Is the fuel system vacuum switch still in place and operational/tested after VRO was removed? Any audible alarms when issue is happening?

[Bigcountry7704]

No it is removed and no audible alarms when it happens.