2001 150 Johnson carb motor, runs strong, but at high rpms it falls flat, can get around 55-57 mph and it almost dies, have to let off gas and ease back into it and runs fine until I get back up to higher rpms, change plugs, wires, coils, carbs rebuilt. Could this be powerpack or maybe fuel pump? Any ideas?
Welcome to the forum. Make sure that the carb throttle plates are not rotating past center. You have a vacuum switch in the fuel system that should sound a horn alarm if the fuel pressure is low. Did you get the high speed jets tight on the carb rebuild? You didn't rebuild the vapor separator tank? Often overlooked but all of the fuel passes through this tank, new needle and seat and float. Also, while your at it, install a new diaphragm in the VST vapor pump. Any other work done on your motor before this started?
Last edited by 316jughead; 02-19-2019 at 03:17 AM.
Originally Posted by 316jughead
Ive checked the throttle and they do not go past half, in fact the look like they could move a little more open but the cam that opens them up won’t travel far enough to allow it to move any more, I can move with may hands and travel past center. The reason for the repairs at first is the Bowls were leaking bad and running horrible, I replaced everything, ordered complete carb rebuild kits and use every seal and gasket. The only thing is there was a little white washer that went under the float valve seat that wasn’t on the old carbs but it showed in the manual to put it there. I set the floats as the specs in the manual for this motor. I’ve replaced all fuel lines and bubble, the vacuum leaks your talking about is that something that’s not on the carbs? This motor also has the vro system on it and the oil part has been bypassed. I seen a lot of people use different fuel pumps for this, is that a thing to try, also something about a screen in the tank. I’m leaning towards a fuel problem
but about out of options lol, thanks for your help.
This guy helped me. Was having close to the same problem. Would run mid 4000 rpm's and after that drop right off. VST rebuild and the diaphragm had a hole in it.
1996 Stratos 201 pro xl
1996 Johnson Faststrike J150GLEDB
OK, first thing, Did you transfer the high speed jets from the old bowls to the new ones? Second thing, no washer on the carbs needle and seats. I don't know what manual you have, but you need the real OEM manual.
Yes i I changed the over the jets, almost didn’t lol. I could be wrong on the manual showing the washer, I also watched a YouTube video and the person on there put that white/clear looking spacer on it, I will remove that. I will also rebuild the vst and give that a try! Thank you for your help, will let you know if it fixes it. Again thanks
Thanks for the info, will give this a try!
First time I rebuilt carbs I accidently put the white washers on the needle seat.Make sure when you take them out you re-adjust your floats.
1998 Ranger R93
1998 Mercury 200 EFI
"Life, liberty, and the pursuit of happiness."
I will, thank you for the reminder!
Reply With Quote