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1990 Johnson 200 carburetor and fuel delivery problems

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Capt.KC

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My 1990 Johnson 200hp (J200TXESM) carburetor high speed/main jets are stamp 62D 0.062" but the hole measures 0.075" It looks like somebody may have drilled them out. Is it common to do this? I'm in Texas if altitude madders. this motor seems to use a lot of fuel. I don't have an exact measurement, but it went through 12 gal pretty quick. The plugs seem to be dark and a little on the damp side. It seems to idle but the acceleration is rough and it sounds like a cylinder is cutting in and out and then clears up. The idle and intermediate air jets are 42 and 36.
I have had other fuel related problem that I've been working on, but since then this is what has been done: external tank with direct connected to hose (no air leak) new 3/8 fuel hose direct connected to duel fuel pump with new OMC kits (pump fuel pressure= 7 psig. at idle (bench tested pump and it held vacuum and pressure with no leak down on check valves and impulse port) The fuel pump was a cheap brand pump. It had a leaking diaphragm I fixed that and tried the motor out and on the top in it would start running out of gas, had to keep squeezing the gas bulb to keep it running. I hope that all of what I've done fixes the problem. Just wandering if the jets being so big, that the fuel pump could not keep up. will find out tomorrow.
Just a FYI I have found out the hard way and want to let others know of things I've found that could be problems for others. I bought one of the light gray fuel hose from Academy and cut the end off so I could connect it directly to the fuel pump. luckily I had pin hole leak at the clamp. When I pulled the hose off to recut it, I noticed it looked like a peace of clear plastic wadded up inside the hose, plugging up the fuel pump port. it turn out to be the hose liner. I did not know these hoses have plastic liners in them that will wad up if you try to modify them. Another lesson learned is cheap fuel pump vs. OMC there is a big difference in the quality in the rubber check valves. After replacing them with OMC there was absolutely no leak down from pressure and vacuum test, the cheap ones would not hold at all.
 
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Also I believe I've come up with a good way to test and measure the the fuel pump impulse line pressure/vacuum. I use an inline check valve with a vacuum/pressure test gauge. the pressure= 3 psig. and turn the check valve in the opposite direction and the pressure= -5 for a difference of 8 psig. and the actual fuel pressure= 7 psig.
Also, might be able to use this method to test the crankcase differences between cylinders to determine leaks from seals and sealing rings.
 
Those fuel hoses are a problem waiting to happen, cut off, or not. Did you do a spark jump test?
 

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No Sir I have not. What should the distance be? The motor has new stator, timing bass, power pack, coils, plugs and wires. as far as this type of hose, I can see how a hole getting through the outer layer not leaking any fuel but causing it to get air in between the layers causing the liner to collapse.
timguy said:
Those fuel hoses are a problem waiting to happen, cut off, or not. Did you do a spark jump test?
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I was using an orifice flow calculator for liquid and at -.1 psig the difference between .062 and .075 is .7 gal/hour X 6 carbs. = 4.2 gal/hour more. that's a lot. any thoughts on this.
 
Plugs are dark, eh? Too much fuel for sure. If the motor has been overhauled/ bored out, then the jets could go up to 64's....not 75's. So they are marked as 62's???? I think you have a problem there. Spark should jump 7/16 to 1/2", nice crackle...blue/white color.
 
timguy said:
Plugs are dark, eh? Too much fuel for sure. If the motor has been overhauled/ bored out, then the jets could go up to 64's....not 75's. So they are marked as 62's???? I think you have a problem there. Spark should jump 7/16 to 1/2", nice crackle...blue/white color.
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The motor has std. pistons. I took it apart after I bought the boat just to inspect and clean. I replace the lower crank bearing and light hone with new rings, seals and gaskets. every thing else appeared to be in good shape. The compression on all 6 cyl. is 90 psig straight across the board. planning on rigging up gauge to test crank case pressure differences to see if I've got a problem with crank sealing rings. The odd thing about the motor was before I made any adjustments, the timing was 23 deg. it is suppose to be 18 deg. which is where it is now. is it possible they drilled the jets to be able to add more timing for more power with out burning a piston?
 
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Yes. Not recommended by me, but have seen people play with that. Probably that's what happened. Apparently you have no history on the motor?
 
timguy said:
Yes. Not recommended by me, but have seen people play with that. Probably that's what happened. Apparently you have no history on the motor?
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Nope! did not have any history on, but I'm making a bunch of bad history! Just a project boat I picked up to fix up as a hobby. Here is the latest verdict, Ran the boat today and it stared surging hard after 5000 Rpm just like if you turn the key on and off. Unplugged the wiring harness at the motor to rule out wiring, did not help. I pull the front carburetor cover and put the fuel pressure test gauge at the card. fuel manifold at wide open the pressure fell to 1.5 psig and I could see tons of fuel going into the engine until it started surging and I could see less fuel with the wife holding the wheel I started squeezing the bulb and the pressure would go up a pound or two but still did not help, but before I could get to the throttle and slow it down, it took out #4 cylinder from running lean. My thoughts are the drilled out jets were using more fuel than the orifice in the needle and seat could keep up with or something wrong with the crankcase sealing on the cylinder where the impulse line connects. as for as the rest of the fuel system goes, Its all been replaced as described above and I had the fuel cap loose. So its back to the drawing board, gotta pull the power head and see if there are any crankcase sealing problems. and probably peace it back to gather and try again before I go with a reman. power head. luckily I don't have much money into it. and got long ways to go before reaching the price of a new motor. any suggestions or theories besides giving up, because I'm not going to let this beat Me lol. To be continued.
 
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Gonna have to think this one over. What did you use to seal the crankcase?
 
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timguy said:
Gonna have to think this one over. What did you use to seal the crankcase?
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I used Loctite 518 along with the primer. Plus heavy coat of paint along the split line as extra precaution. did not see any signs of oil or any kind of leaks. Did not have any trouble with the upper or lower seals but will inspect them when I get it torn down Might have broken a crank sealing ring but there did not seam to be any trouble putting it together. some other wild thoughts, is that maybe the cylinders have to much piston to wall clearance, allowing exhaust back pressure into the crankcase. will be buying some measuring tools to check and inspect before putting it back together.
 
How much piston to bore clearance? Did you check...??? Yes that might be excessive. I don't like to see more than .004. In other words no more than 1,000 of an inch per inch of cylinder bore.
 
it used 9 gal. in less than 30 mins of run time. the fuel pressure was 7 psig yesterday and today after it's melt down it is 3 psig at idle. any clue of what it should be
 
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I was told that these 90 deg loopers tend to fail premature before they wear out more than other motors and if true whats the most common thing that causes engine failure
 
timguy said:
How much piston to bore clearance? Did you check...??? Yes that might be excessive. I don't like to see more than .004. In other words no more than 1,000 of an inch per inch of cylinder bore.
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No, I did not have anything to measure it with, just went with the notion it was running before they let it set up for years. so i just disassembled and cleaned, visual inspected it. the bottom bearing had rust and tar like stuff so I replaced it along with a seal and gasket set and new piston rings. did not want to put much into it until I knew how this boat was going to handle rough water, By the it seams to do well, its an old 20 Grady White center console. I'm now questioning if this model motor is worth doing anything with. bot i'm going to keep working on this until I figure what's going on with it.
 
I like the original JOHNSON/EVINRUDE manuals. Clearances I learned in school......school of hard "knocks"....ha!
 
timguy said:
I like the original JOHNSON/EVINRUDE manuals. Clearances I learned in school......school of hard "knocks"....ha!
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I hear ya, I've been going to the school of "Hard Knocks" here lately but some times that's what you gotta do to know what works and what don't. Like when we were told as a kid, "that the pot on the stove is hot! don't touch it!" but most of us had to see for our self to see what they were talking about, so we touch it or at least I did. I feel like that 'Hot Pot" is calling right now, wanting me to tear it down and see what went wrong. By the way Thanks for all of the replies.
 
Your gas usage is near normal as motor will burn 20 gallon a hour at 5K RPM plus. Pulling and running it with front airbox removed is what likely what leaned it out as that is a restrictive type airbox. Running them with it removed or inner spacer or foam removed will cause leanness.
 
faztbullet said:
Your gas usage is near normal as motor will burn 20 gallon a hour at 5K RPM plus. Pulling and running it with front airbox removed is what likely what leaned it out as that is a restrictive type airbox. Running them with it removed or inner spacer or foam removed will cause leanness.
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That's probably what got the piston. The motor was surging bad after 5000 rpms with the air box on, engine cover on. I took the air box off as a last resort to maybe be able to see a difference in fuel flow and it was lower flow coming out of the draw tube when it started surging. inline pressure test gauge at the carbs was 1.5 psi when it was surging. Along with low fuel pressure and the main jets being drilled out to .075 marked 62D= .062 sucking the fuel bowl dry and uncovering the jet each time it surged. check the fuel pump and the check valves and diaphragm are all holding pressure/vacuum and no fuel flow restrictions. if 1.5 psi is not enough to push fuel though the needle and seats, then it's probable a crankcase vacuum/pressure problem. any other thoughts or suggestions are welcome. Thanks for the reply.
 
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