'93 Evinrude Intruder 150 Won't do More Than ~4k RPM

[ajmeyers4]

1993 Evinrude Intruder 150 (E150GLETG)
14.5-24p Raker
~4.5” prop to pad

1993 Champion 176 SCR


Background: Got this boat late last fall. Ran it one time and it was perfect, but never pinned it because of conditions. I topped off tank, treated fuel w/ startron, and fogged it down. I assumed PO used non ethanol(yet to drain water sep). PO rebuilt all 6 carbs, new “power ignition pack cdi”, optical sensor, and plug wires. Come this spring I’ve had some issues:


First time out I couldn’t get over 4K rpm and had major smoking, stalling, and vacuum(I think) alarm at full acceleration. Assumed VRO went out, so I got used oem dual stacked fuel pumps and premix. Replaced fuel barbs with 3/8”, rebuilt both pumps, new lines, bulb, no anti siphon valve, rebuilt VST, and replaced plugs.


Went back out had low end bog/acceleration issues and still couldn’t get over 4K rpm. Found that the timing adjustment was off so I made sure the throttle roller and timing roller are both touching respective cams. They advance at the same time and butterflies are wide open at full throttle. I did notice the clear piece on the throttle roller is missing, ordering that. Could that be causing loss of top end rpm?


Holeshot is significantly improved. Idle is alright, a little shaky and occasional seems to cough/sneeze. Did cylinder drop test at increased idle speed and it seemed like all were firing but a little hard to tell. Had audible/visible spark on all cylinders. Plugs all pretty much identical, pretty clean light brown. Maybe a tad lean. Did decarb treatment with seafoam and ran on remote. Still can’t get over 4200 rpm and 55mph(gps) trimmed out with 1 person, half tank, fishing gear, and empty wells.


Idling at 800 neutral and 650 in gear. Also PO removed shift interrupt switch, need to replace that(clunks hard into gear and sometimes hesitates coming out of gear). It runs smooth on the top end and drinks gas. It went through a gallon of decarb/gas/oil mix when running on plane at 2-2.5k rpm in about 13 min. Pushing key in for primer at high speed makes it bog down, making me think I’m not starving for fuel or have air leak?


Going to do a compression test and a proper spark test tonight. If that checks out I suppose it’s time to tear into the carbs. None of the bowls are visibly leaking, but perhaps a warp air leak? Or I have bad ignition timing or component(s)? Or tachometer is off and this is how it should be performing? I know the motor should be raised an inch or so. Have a 6" plate I'm yet to put on. Prop has a couple small dings. I know that was a lot of info, just trying to be as detailed as I can. Any advice would be greatly appreciated. Maybe I'm overthinking this. Thank you.

[ChampioNman]

If the white nylon washers that come in the carb kits were used they need to be removed they aren't used in the plastic carbs can throw off float drops. Also make sure your high speed orifices are fully seated in the float bowls. If they aren't or a missing the high speed circuit will never cut in, could be why you are getting the fuel restriction alarm. It comes on around 4K the same speed that the high speed circuit kicks in.

[ajmeyers4]

Thank you for you help ChampioNman! I've probably read over a 100 threads trying to soak up some of your wisdom on these motors.

I think I finally found my issue, I was way overthinking it! I started pulling carb drains to check the high speed orifices are all seated. I pulled one all the way out and wouldn't you know it I could barely see any light through it. Blew through it with my mouth to reveal how big the hole should be and then it all made sense why I'm not reaching full RPM.

Going to take it to the lake and confirm this was the issue. I'll do a full clean of all of the carbs thereafter. The PO must have crap gas(I even treated it). I'm surprised the midrange and idle is not clogged with how clogged the biggest jet is? Maybe it's because its on the bottom?

I'll also run a compression and spark test to rule those out before I test it out. Fingers crossed this is it and hopefully the little full throttle running I did didn't lean it out too much. (never did get overheat)

[ChampioNman]

Two different circuits that's why you didn't know you had an issue, remove and clean them and you should be fine. Berryman's carb cleaner works very well The orifice size is on the smooth end of the orifice.