1985 johnson 150 gas pickup problems

Hey guys a couple months back i bought a boat with 1985 johnson 150 outboard on it and have been fixing all the little things that were done wrong to it. now i am only a few steps away from having a great running motor. My problem currently is that when running at about 3/4 throttle or more my motor will suddenly bog down. i can let of the throttle all the way once or twice then hit it and it will pick up again. would an air leak at the block create this? also as i mentioned several things were done incorrectly on this motor, i has 2 premix vacuum pumps on the block. One pulls the fuel from the tank and the other pushes it into the carbs through the same setup of hoses that the VRO did. i would like to know what the part numbers of those pumps are supposed to be when correct. also i want to make sure that the hosing is ok the way it is. The only place there could now be an air leak on this boat would be either the plastic rod that runs to all the carbs or on the block itself. everything has been rebuilt and checked. Thanks alot for any help! its fishing season and schools almost out i wanna be on the water!

Re: 1985 johnson 150 gas pickup problems

air leak will often cause a miss at idle. irregular idling
Check that the wiring for the timing isnt shorting out somewhere when it advances when the throttles at 3/4
Does it go alright at wot?

Re: 1985 johnson 150 gas pickup problems

Sounds like someone has retro fitted that engine with a set of older dual fuel pumps. That setup was last used on the 1983 V6's. Those two premix pumps should normally work well on that engine. The original dual fuel pumps had different part numbers. Upper pump:393648 supercedes to: 438559 Lower pump: 393650 supercedes to: 393870. Supercession has both pumps superceding to the same pump number, though the upper pump supercedes to a pump kit part number, which comes with a special hose for it's application. If the engine starves for fuel when running above a certain rpm, it's possible that the engine is running out of fuel. This happens when one or both of the fuel pumps is weak and won't supply enough fuel to feed the engine above that rpm. May run fine at lower rpm's then bog at higher rpm's. The carbs are probably consuming more fuel than the pumps can deliver, so the carbs begin to run dry. Also possible that there is a fuel restriction, such as a faulty anti-siphon valve or a problem with the fuel hose/fuel hose bulb. You can look at the original factory hose diagram at the factory website for their parts catalogs: epc.brp.com. Look for an 83 V6 engine, then to the fuel pump diagram.

Re: 1985 johnson 150 gas pickup problems

it idles perfectly and even even starts fairly easy. i cant go past 3/4 idle 1 because it it bogs down after a few minutes and two because at wot this boat runs in the low 70's and im not too so i can't just floor it to that speed. and it shouldn't be electrical if i can let of the gas once or twice than hit it again and itll go?

Re: 1985 johnson 150 gas pickup problems

ill check those numbers and i found a 1983 parts diagrham and believe that mine are set up backwards. i have another fuel bulb to try as well. but one pump is brand new and the other is newly rebuilt. those are tricky little buggers to put back together haha. there is no antisiphon valve just the fuel bulb. and ya that what im trying to figure out like i said this boat can run in the low 70's but its also a stock motor as far as horsepower goes so i think ill try the other fuel bulb and rig the pumps the right way.