Idle/start problems '73 Johnson 135 v4

[sparkroost]

Re: Idle/start problems '73 Johnson 135 v4

Still sounds like link and synk or air leaking somewhere. You really can't link and synk by sight!<br /><br />Another thing to consider.. the carbs have a plug in them, about the size of a dime. Under that plug is your idle circuit. The idle circuit comes out 3 holes near the throttle plates. If you have an obstrustion in there you will get inconsistant idle. To be positive on the carbs not being it you will need to remove the plugs, all the jets and soak in berrymans carb cleaner. But you have to remove any rubber/nylon bushings from the throttle shafts. If you have to remove the throttle plates, be sure to get new screws and "peen" them over after re-assembly with loc-tite.<br /><br />Warm engine. Pull that linkage bar off the carbs. Start motor. Will she idle now?(will be really low idle). You may be surprised.. it might just idle at 400-500 when you do this. If so, it's your lynk and synk! Remember, lynk and synk only applies to idle and off idle. WOT the engine does not care unless they are WAY off.

 

[SCO]

Re: Idle/start problems '73 Johnson 135 v4

Thanks spark. I am ready to do the fingers tests(per Joe) and sync tests. I did remove the idle circuit core plugs and they are perfectly clean. The three holes are good to the barrel . At some point. someone had damaged one of the three carb casting holes when prying out the core plug on 1 of the 4 circuits, but it partially closed the hole and I filed it back to the size of the other identical one with an 031 drill bit. There was no observable distortion of the casting. I don't think it could be the problem though Ill keep it in the back of my mind. I cleaned all passages w the tuner and shop air soak repeat soak repeat.... The idle when warm on the muffs is good.

 

[sparkroost]

Re: Idle/start problems '73 Johnson 135 v4

Sounds to me like you just named your problem.<br /><br />Look for another carb my friend.<br /><br />Goto hardware store...... Buy 4 1/8" nipples. Buy 1 vaccum gauge. Get a "T" and about 6' of 1/4" hose. You will also need 4 plugs(the rubber ones that fit over the 1/4" nipples(can't remember what there called).<br /><br />Take intake off. Drill 4 holes into intake, near the carbs. as close to center of throat as possible. 1 hole in each throat. Thread for the nipples you bought. Screw in nipples. Put rubber caps over nipples. Re-assemble. <br /><br />Remove 2 caps on the port side. Cut 2 pieces of hose 2ft and 1, 1 ft..<br /><br />Connect 2 ft. hoses to nipples and to "T". Connect 1 ft. hose to gauge and "T".<br /><br />now.. as the motor runs you are going to see the needle jump up and down. You can do a variety of things to dampen this out. You need to restrict the inside diameter of the hose to stop the jumping. Ideally you would use a valve inline at the gauge. Then you close it off until you have slight to no bounce. You can stick a drill bit in the hose also at the gauge. You just have to find the right size to get it where you want.<br /><br />One you get it running and up to operating temp you need to get it to idle, whatever it takes. if you have to increase the throttle, do it.<br /><br />Block off one line and check reading, block other line off and check reading. Adjust link and synk until they are even.<br /><br />Note vaccum readings for port side and verify starboard side is the same or within 2 in. hg.<br /><br />On another note. Did you remove your exhaust plate on the back and check for carbon blockage?

 

[SCO]

Re: Idle/start problems '73 Johnson 135 v4

Maybe so, but it's just a scratch(deep scratch), how finiky can these things be? I didn't check the exhaust for carbon. I like the techniques you mention, but makes me think that if reeds not equal or there is some internal leakage this method will mask those probs( maybe a good thing). Do you think I should check cranking vacuum on all 4 intake ports first? I think I could do that with a piece of sheet aluminum with a gauge on it duct taped to the intake with throttle set at full. Thanks again for these ideas. first I will try disconnecting the throttle and insuring it fully closed along with the choke to see if I can pull fuel in faster. Seems like it is taking a long time to get fuel from the carb to the pistons. I can see your point that if the exhaust is impeded that it might not be drawing properly.

 

[SCO]

Re: Idle/start problems '73 Johnson 135 v4

The 6 seconds to first fire is what bugs me most. Shouldn't the squeese bulbs fill the bowls to the brim and stop filling when the float shuts off the the flow causing bulb to harden? If carbs full, then fuel should immediately mix with air and fire I'd think, but it is like I have to fill the crankcase with fuel before there is enough fuel in the air to fire.

 

[sparkroost]

Re: Idle/start problems '73 Johnson 135 v4

just cause the bowls are full does not mean it will get sucked into the cylinders. If you are fully closing the choke(have to look by eye to see if they are closed all the way) This may be your cold start problem. If they are closed ALL the way when choke on.. you have a vaccum leak somewhere. It's like sucking on a straw. If your mouth is not on the straw all the way it takes more suck to get the water to come up the straw. those choke plates have to completly cover the carbs. You should be able to tell by when you close the choke and try to start, open the choke back up and look for fuel all over the front of the carbs. If not present you are not creating enough suck. Usually air leak.

 

[SCO]

Re: Idle/start problems '73 Johnson 135 v4

where would this air leak be crankcase, flappers, seal carb body to motor? how do you check vacuum leak?

 

[SCO]

Re: Idle/start problems '73 Johnson 135 v4

Are carbs vented? If you cut pinch the fuel supply, doesnt the motor run till the bowl drains. Air has to replace the fuel that is being sucked out until the fuel supply valve opens(y/n?). I know this is an ignorant question, but trying to rule out a clogged vent possibility.

 

[sparkroost]

Re: Idle/start problems '73 Johnson 135 v4

crankcase pressure causes the fuel pump to pump fuel. There is not constant pressure there. They are pulses. when the pressure goes low, a spring returns a diaphram in the fuel pump to normal position. Then when it pressures up again it moves the diaphram to pump fuel etc. etc..<br /><br />when the piston travels downward it causes a "suck" effect in the intake area. This draws fuel out of the carb and into the motor. If you have a leak in the intake manifold OR carb bases, it will not suck enough fuel.<br /><br />When you first start it, pump the bulb until hard. open your air box and manually hold the choke down all the way. Crank. Should start to fire in about 5 seconds of cranking. Depends on how cold it is outside. The colder it is the more dense air is and the LESS fuel you will be getting cold. Once you get it warm the air is less dense. Less dense air needs less fuel to obtain the right mixture.<br /><br />Don't worry about the cold start problem for now. Get the thing to idle first and worry about that later.<br /><br />A vaccum test will tell you where you are at. Forget about the reeds.. All they are is a 1 way valve and prevent air from blowing back through the carbs when there is pressure at the intake port when the piston comes back up.<br /><br />Do you possibly have the throttle plates open when you try and start it cold? Look at the cam and see if the plates are closed.<br /><br />This sounds so much like link/synk/air leak problem. did I say that already?<br /><br />Get'er running and squirt something flammable around the intake and carb bases... I bet you find it changes idle speed. If it raises you have an air leak.

 

[ledgefinder]

Re: Idle/start problems '73 Johnson 135 v4

The carbs have a vent passage. <br /><br />For what it's worth, I have what sounds like exactly same behavior from a 1979 100hp Johnson. Have to crank it about 10 seconds (full choke) before the first burp, then it fake starts about 10 times (enough of a burp to kick it off the starter), then finally is starts shaking to life. Seems like it's not hitting on all 4 when real cold. Once warm it idles OK, not great; plenty of top end (19" prop to 6700). I'm guessing dirty carbs, but have a couple other motors to get to first & plus it's still 30 degrees out here. This motor has pretty much the same carbs as yours, but different ignition.

 

[CARLOS]

Re: Idle/start problems '73 Johnson 135 v4

SPARK,<br /><br />YOU HAVE MENTIONED THAT, "COLD AIR IS MORE DENSE AND YOU WILL NEED LESS GAS"...<br />NO, I THINK YOU ARE IN ERROR. COLD AIR IS MORE DENSE AND YOU WILL NEED MORE GAS TO INFLAMATE AND OBTAIN A BETTER COLD IDLE...<br />ANYWAY, I RECOMMEND TO SCO, TO CHECK FOR AIR LEAK AT THE AIR INTAKE MANIFOLD OR REEDS POOR SEALANT WORK...ARE THEY WORKING FINE? REMEMBER 2 STROKE ENGINES NEED GOOD REEDS SEAL FOR "GOOD RESPIRATION ENGINE".<br />VERY GOOD FORUM... FROM VENEZUELA I´M WITH YOU...<br /><br />CARLOS SCHEMEL<br />VENEZUELA

 

[SCO]

Re: Idle/start problems '73 Johnson 135 v4

I've got to apologize , because I found yesterday that the advance and throttle valve were not properly synchronized at idle. I made the assumption it was ok because 2 mechanics had tuned it up. Maybe it doesnt make a difference , but will retest tonight. Heres what I found:<br />At idle, the throttle valves are fully closed, spring loaded closed. What I noticed was that when I pulled up the neutral throttle lever at the control box, the throttle valve on the carb did not move. The roller did not come into contact with the throttle cam(with the neutral throttle lever at full on the control box).I then scoured my service manual to determine that the sync wasnt set right. With the neutral throttle lever all the way down, the roller is well past(on the low throttle side) the scribe mark on the throttle cam. I will set the roller at the scribe mark so that the flappers on the throttle will open some when I pull up on the neutral throttle lever on the control box, and see if that solves the problem. I'll also get a check on the low throttle timing and flushette rpm before and after.<br />BTW, I put 2 fingers in each carb barrel at idle and saw no change in idle, but if anything a slight slowdown, so I think that the mixture must be ok.

 

[sparkroost]

Re: Idle/start problems '73 Johnson 135 v4

Ledge, you are correct! MY MIsTAKE!!! I was getting long winded!! Sorry for my error.(you know that's what I meant, lol)

 

[sparkroost]

Re: Idle/start problems '73 Johnson 135 v4

OOPS, I meant Carlos.<br /><br />I work as a tech./troubleshooter for many things in the industrial world. I love to troubleshoot. It's like a puzzle to me. Hope I didn't throw ya off on the "need more fuel when cold bit".<br /><br />Just trying to help ya SCO )

 

[sparkroost]

Re: Idle/start problems '73 Johnson 135 v4

Just to let you know SCO, the "link and synk" were talking about is the linkage that connects the top carb to the bottom one. Trust me.. it can look the same, but.... can you see .010 difference in the plates? I don't think so. That is why it's hard to link and synk by eye. If 1 of those plastic clips are worn where it goes through the hole, you will get slop and the bottom carb will open later than the top one. This will cause the engine to stop abruptly, idle funky or not at all.<br /><br />You can do away with all that by buying the turnbuckles I described. You might try and buy new plastic linkage clips, but you will probably find that the holes on the actuater might be enlarged.<br /><br />I am going to be doing some carb work this weekend and I will set mine up with the turnbuckles and take a pic for ya.

 

[sparkroost]

Re: Idle/start problems '73 Johnson 135 v4

Carlos...that's not what I said in the post...<br /><br />"The colder it is the more dense air is and the LESS fuel you will be getting cold."<br /><br />I guess I wasn't in error, he he...

 

[SCO]

Re: Idle/start problems '73 Johnson 135 v4

How about this" the colder, the leaner the mixture".<br />I appreciate the help. The posts yesterday got me focusing on the timing/carb sync. I did realize that you were talking about carb to carb sync, but at this point it is not a factor because both carb throttles are fully closed w motor in neutral , even at full neutral throttle.

 

[sparkroost]

Re: Idle/start problems '73 Johnson 135 v4

SCO.. I think you are missing the point here. It's impossible to visually "see" if they are even. They can look fully closed at idle, but as soon as you open them just a little bit, that is where you have the problem. That is why synking requires a vaccum gauge or trial and error. A .010 difference in the plates will cause a substantial difference in flow vs. top to bottom carbs. Also the "vent" holes that have been spoke of... hopefully someone didn't mismatch the carbs. If those vent holes are not the same diameter on all 4.... you can try and synk all day long and not achieve a idling motor.<br /><br />Reason I am harping on this so much is cause your motor is old and worn. To get it right takes some improvisation due to wear.

 

[acc]

Re: Idle/start problems '73 Johnson 135 v4

Hey Captain, I'm no expert but had a similar problem with my 99 Yamaha 115....<br /><br />After carburetor experts did $250....the problem persisted.....Finally I connected the gasline from my Johnson kicker motor to the Yamaha....Bingo!!!......<br /><br />Then I started replacing things starting at the Yamaha engine and working toward the fuel tank....hose, connectors, bulb, more hose, then funny thingy at the fuel tank....It had a ball in it to allow fuel flow from the tank but inhibit fuel flow back into the tank.....That was bad.....<br /><br />Simple! Good Luck....

 

[SCO]

Re: Idle/start problems '73 Johnson 135 v4

I'm not missing your points Spark, keep em coming, but found that the roller is not touching the throttle cam. I can push on each carb throttle individually and determine that each is closed all the way. Once I get that taken care of, and set up as per service manual, I may no longer have a problem if I get lucky. At that point I'll begin synching carb linkages, replacing castings etc.. Did you read the post where I apologized? I did so because we're doing all this diagnosis and I didn't yet have it set up per the service manual.<br /><br />Thanks Acc, wish I could be so lucky, that problem has been ruled out. Glad to see you've found the board, welcome aboard.