96 90hp running lean in higher rpms

hello all. I have a problem im trying to figure out. first heres the background. 96 90hp johnson V4, on a same yr hydro sport. bought it from a man who let it sit for 5 yrs in his garage, i know bad right. so i begane with rebuilding the vro and closing off the oil side. new vapor chamber gasket. cleaned the carbs. it idles at 1000 rpm. now when i rev up in wot to about 3500 or so a few times it starts to lull and idleling sounds funny and low. sounds like its sucking air somewhere to me, so replaced all the pring clamps on the intake fuel side with ratchet clamps. not as bad but stills does the same thing. after i shut it off i prime the bulb up again and it acts normal again. is there something im missing that would cause this? im kinda running out of ideas here. no gas is leaking anywhere so has to be a air leak for it to run lean like that? thanks to all replys

Re: 96 90hp running lean in higher rpms

ok, i have drained the tank thinking water maybe the issue. very little water was present. made no difference. still stupped, may have to break down and take it to the boat yard ugh

Re: 96 90hp running lean in higher rpms

now when i rev up in wot to about 3500 or so a few times it starts to lull and idleling sounds funny and low.

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I hope you are doing this in the water in gear and not on a hose or barrel... sound like air leak in vapor tank or air motor in VRO is not working correctly.

Re: 96 90hp running lean in higher rpms

Try a test. When running the engine in the lake, have a friend constantly prime the fuel hose bulb. This will force extra fuel into the carbs. If the engine runs fine at WOT, as long as you prime the fuel hose bulb-you've got a fuel delivery problem. Possibly a weak fuel pump, bad fuel line, clogged anti-siphon valve.

Re: 96 90hp running lean in higher rpms

thanks for the replies. yes im doing this in the lake, have read otherwise thats a no no. ok, went throught the fuel pump again and carbs, carbs are all gd, a o ring was missing in the fuel pump and a flapper had slid out of place during assembly of the fuel pump, both are corrected. runs yet a lil better but still same results. there are 2 small o rings that go on the nipple that slides in the vapor chamber, they are ordered. thought why not, its all thats left to replace. will let you guys know if thats the problem os if anybody else has the same issue. one other question, would the primer bulb cause this even if it pumps up hard?

Re: 96 90hp running lean in higher rpms

ok, after replasing the primer bulb and checking the ati siphone valve which has been guted out already. i went back to the vapor chamber to recheck the gascket. the float was way out whack, not sure if i bent it up or was done before. i got it reajusted to the manual specs. 1 1/4 inch drop, where as before there was no drop. though this has been something so simple to fix, i did get to know my motor better in the process. thanks to all for your help and advice. hope this helps others