1988 Johnson 150 saga, (nightmare) lol

[LarryPitts]

Let's start at the beginning. Last summer I replaced some leaky lines and the fuel filter on my motor. After a trip or two, (I'm guessing) I took boat out and got about a mile from ramp running flat out and motor bogged like it was running out of gas. It got worse as the day wore on so I started researching what it could be. About 3 people told me my motor would probly need to be rebuilt as that's how theirs acted when it went down. I finally got it in the shop and sure nuff it was kinda fried. Both heads were leaking water so he tore it down. It was wore out! One cylinder had been bored out to .030 already and you could almost see daylight around the others with dings all in one. Got it overhauled, bored to .044 over with forged pistons and had two cylinders replaced by a machine shop. Also had heads replaced with used units.
Motor really sounds good but still have the bogging problem, dang! Replaced fuel line and primer and pumps up good now with no visible leaks but still gets up on plane and acts like it runs out of gas after about 100 yds. Doesn't die completely, just slowly comes down off plane and idles fine. You can nail it and it does it all over again. When it falls it will surge just like it is running out of gas, will actually stay up on plane if you leave the throttle open but I don't want it to starve for lube so I putted around the rest of the trip. Mechanic is gonna come work on it after while but wanted to post and get feedback from forum. I'm thinkin maybe problem with my work or maybe fuel pump gettin weak.
Also if I get it running good and start to build a little confidence with it, is this a rig I should keep for a while or should I maybe look at doing some trading in the near future. I've heard .040 is kinda borderline and wonder if .044 is more for racing apps. My mechanic and the machine shop didn't seem to be greatly concerned about boring that far. Also we didn't tear the crank down and replace the main bearings, just the rod and piston bearings. Mechanic said he only did that if there was a problem with the crank and usually just replace as a unit. The boat is a 17.5' Champion, 88 also. Also my mechanic told me my power head had been replaced at one time and is an Evinrude. I said "same thing, right?" and he said "yes and no." Don't know if he was blowin smoke or what but said there was slight design differences in the casting and had to get different gaskets for it. He didn't charge me any extra for it but it could have been a stalling for time! lol! Anyway it really fires right up and runs smooth so I'm kinda excited bout gettin it goin. Should I let my confidence build and drive it like it's new or be careful with it and sell it soon. I will not unload it on some unsuspecting person, friend or stranger alike so I will probly take a beatin money-wise if I don't use it for a few years. I really like the rig and would like to use it awhile. I'm lookin forward to the forum's response. Sorry for the long post, lp

 

[glenn property of pam]

Re: 1988 Johnson 150 saga, (nightmare) lol

its always hard to read someones disciption of what its doing. im reading that when you punch it the boat goes on plane then the engine revs like its staving and the boat falls of plane?.......if im wrong then ignore this advise.......think ya spun the prop. mark the prop and the hub then punch it then see if the marks no longer line up.

 

[emdsapmgr]

Re: 1988 Johnson 150 saga, (nightmare) lol

Your middle paragraph sounds like the carbs are running out of fuel. If a fuel pump is weak, it will only pump so much fuel. Enough to idle and perhaps run at partial throttle. If you go to full throttle the engine may run fine, till the engine sucks the fuel down in the carbs-at which point the engine will go to idle. As soon as the fuel pump refills the bowls, the engine can run full throttle for a while till the cycle repeats. You can perform a test: next time you are out boating and the engine bogs, have someone constantly prime the fuel hose bulb. This will force extra fuel into the carbs. If the engine runs fine (at full throttle) as long as you constantly prime the fuel hose bulb, it's a fuel delivery issue. Likely the pump, but could be a bad hose, sticking anti-siphon valve, etc.

 

[LarryPitts]

Re: 1988 Johnson 150 saga, (nightmare) lol

May have found the problem. The cold start device (choke but not a choke) has 4 lines coming out of it, 3 go to carb base plates and one goes direct into the manifold. Someone had broken nipple off and reshaped it enough to get the hose barely stuck on. Mechanic stuck it back on but it fell off when he put the other lines on. Was leaking fuel with motor shut off but probly sucking air while running. Woohoo, hope this is it. I remember this from when I was changing fuel filter and replacing fuel lines, bet it came off then, causing my initial problem.

 

[LarryPitts]

Re: 1988 Johnson 150 saga, (nightmare) lol

Nope, still runs out of gas on plane. New fuel line with primer bulb, holding prime. Next stop fuel pump, what seems to be best fix for bad VRO style pump? (oil been disconnected for a while) Electric pump, original with dummy vro, or the double pump setup? Thanks, lp

 

[LarryPitts]

Re: 1988 Johnson 150 saga, (nightmare) lol

Picked up my mechanic and went to local lake. Did the primer bulb pump test, boat runs awesome as long as you pump the bulb. He's pickin up a used pump for me tomorrow. Things are lookin up!!!

 

[j_k_bisson]

Re: 1988 Johnson 150 saga, (nightmare) lol

You might want to check for a couple of things before spending the money on a pump. Like check for an old water separator and fuel filter. These do often gum up over winter and cause a minor fuel flow problem. Sometimes enought to limit fuel low at higher RPMS. Also the primer bulb will over come this. Just a thought.....