rough idle and I have a question about the s. plugs

[fishfeatures]

hi

89 johnson 60hp

I have attached a new power head and am just fine tuning it out. I have it idling at 800 in the water and about 1200 on the muffs. I notice though it's running slightly rough.
Compression is within specs and i have good spark and the timing has been done with a light and that is within spec too. However when running if i remove #1 plug lead the motor will start to die #2 nothing really happens when lead removed and #3 will make the engine start to splutter and die a few seconds longer than #1 results.

Now as I said I have good spark going to #2, I even changed out the coil (but knew this wasn't the issue), changed leads from #1 to #2 and vice versa and still same result. Even changed around the spark plugs and the result was the same.

I'm thinking that if i pull each lead off the reult should be the same no matter what cylinder ..yes?? also aren't these 3 cyl loopers good to run on 2 cyl? I'm thinking of borrowing another comp gauge as this is the only reason i think the engine dies when #1 or #3 is removed. I don't think all 3 cyl are good.... oh also new head gasket went on to the motor and all bolts torqued and rechecked while i was running my water tests.


Any ideas or am I just over thinking this? I haven't had it out for a proper spin yet as I am waiting for it to be spot on before I UNLEASH my new motor on the bay...

 

[Joe Reeves]

Re: rough idle and I have a question about the s. plugs

Start with the basic trouble shooting procedure to avoid expensive errors!

Compression... What are the readings on each individual cylinder?

Spark... With the spark plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! Does it? No spark tester? Build the following.

(Spark Tester - Home Made)
(J. Reeves)

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:


..........X1..........X2

.................X..(grd)

..........X3..........X4

You say that you just attached a new powerhead. Have you corrected what caused the old one to blow up? If not, expect a repeat of the problem.

Have you dismantled and cleaned all of the carburetors? If not, do so, otherwise the cylinders will not be receiving their proper mixture.

Spark plugs should be CHampion QL77JC4 plugs gapped at .040 (original recommended gap) or .030 (revised 1990+ gap).

And yes, removing any of the spark plug wires when running should cause a equal drop in rpms.

 

[fishfeatures]

Re: rough idle and I have a question about the s. plugs

Joe,

comp readings are 112 108 113 ( with #2 reading low and that being the prob one I think a retest is in order)

Spark done with tester ....but champion plugs are harder to come by and I was informed here before that NGK can be used.

Old powerhead wasn't used for a while and head gasket was well eaten so I replaced that and all other basics but there was rust on the lower rod bearing and it dis integrated . I guess i should have open it up fully.. but hey hindsight is a great device...

All carbs have been gone through 3 times as I was getting a lean sneeze from 2 of them but not anymore.

If removing a wire causes an equal drop in RPM then i have a issue in cyl 2. I reckon so it's either fuel or comp. How do you check it cyl is getting fuel?? I'll do a new comp test with another tester as I'm not trusting mine right now.

 

[Joe Reeves]

Re: rough idle and I have a question about the s. plugs

In reading your latest post (#3 above), it comes across that you have not replaced the powerhead (block, crankshaft, rods, pistons, etc) but have rather just installed a different cylinder head. If so, then yes, you've taken a short cut to repairs and anything can still be a problem.

Compression on a 1989 three cylinder engine should be higher than what you state but should still run better than what you describe.

Checking for fuel delivery..... Carburetor face plate off, engine running, stick two fingers into the carburetor throat acting as a manual choke. You should feel fuel flowing around your fingers. If the engine immediately dies down, fuel is flowing normally and you are simply flooding that cylinder out. If the rpms increase somewhat, that cylinder is running lead..... scored damaged piston, faulty reed plate, fouled carburetor, something of that nature.

 

[fishfeatures]

Re: rough idle and I have a question about the s. plugs

In reading your latest post (#3 above), it comes across that you have not replaced the powerhead (block, crankshaft, rods, pistons, etc) but have rather just installed a different cylinder head. If so, then yes, you've taken a short cut to repairs and anything can still be a problem.

Compression on a 1989 three cylinder engine should be higher than what you state but should still run better than what you describe.

Checking for fuel delivery..... Carburetor face plate off, engine running, stick two fingers into the carburetor throat acting as a manual choke. You should feel fuel flowing around your fingers. If the engine immediately dies down, fuel is flowing normally and you are simply flooding that cylinder out. If the rpms increase somewhat, that cylinder is running lead..... scored damaged piston, faulty reed plate, fouled carburetor, something of that nature.

No it was a complete p/h changeover Joe, crank and rods in old one were out of round.I'll check the fuel delivery the way you mentioned and see what happens..
Thanks for the advice Joe.

 

[Joe Reeves]

Re: rough idle and I have a question about the s. plugs

Noticed an error in my recent reply, corrected as follows.

I stated "If the rpms increase somewhat, that cylinder is running lead....." Should have been "If the rpms increase somewhat, that cylinder is running LEAN....."

 

[fishfeatures]

Re: rough idle and I have a question about the s. plugs

Noticed an error in my recent reply, corrected as follows.

I stated "If the rpms increase somewhat, that cylinder is running lead....." Should have been "If the rpms increase somewhat, that cylinder is running LEAN....."

Kinda thought as much

 

[fishfeatures]

Re: rough idle and I have a question about the s. plugs

hi

89 johnson 60hp

I have attached a new power head and am just fine tuning it out. I have it idling at 800 in the water and about 1200 on the muffs. I notice though it's running slightly rough.
Compression is within specs and i have good spark and the timing has been done with a light and that is within spec too. However when running if i remove #1 plug lead the motor will start to die #2 nothing really happens when lead removed and #3 will make the engine start to splutter and die a few seconds longer than #1 results.

Now as I said I have good spark going to #2, I even changed out the coil (but knew this wasn't the issue), changed leads from #1 to #2 and vice versa and still same result. Even changed around the spark plugs and the result was the same.

I'm thinking that if i pull each lead off the reult should be the same no matter what cylinder ..yes?? also aren't these 3 cyl loopers good to run on 2 cyl? I'm thinking of borrowing another comp gauge as this is the only reason i think the engine dies when #1 or #3 is removed. I don't think all 3 cyl are good.... oh also new head gasket went on to the motor and all bolts torqued and rechecked while i was running my water tests.


Any ideas or am I just over thinking this? I haven't had it out for a proper spin yet as I am waiting for it to be spot on before I UNLEASH my new motor on the bay...

OK,

I redid the compression with another tester and got 120, 113,120. I have noticed that my tach is now not working. I had a dead battery the other day and jumped it form the car. I think I have blown the rectifier and so this is causing an intermittent spark on all cyclinders which I only picked up with the timing light. Could a blown rectifier somehow cause spark firing issues??

 

[the machinist]

Re: rough idle and I have a question about the s. plugs

Not sure about the rectifier & will let Joe respond to that, but you might pull the #2 spark plug boot & cut 1/2" off the lead, reattach it. it could just be a bad electrtical connection at the boot.

Or it is possible that someone stripped the #2 spark plug threads & has Heli Coiled it. IF so sometimes this threaded insert does not ground well to the aluminum head & can cause erratic spark into the cylinder.

 

[Joe Reeves]

Re: rough idle and I have a question about the s. plugs

That model should have the small three (3) wire rectifier. It has nothing to do with the ignition and can be tested easily as follows.

(Small Rectifier Test)
(J. Reeves)

Remove the rectifier wires from the terminal block. Using a ohm meter, connect the black lead of the ohm meter to the rectifier base (ground), then one by one, connect the red lead of the ohm meter to the yellow, yellow/gray, then the red wire (some rectifiers may also have a fourth yellow/blue wire. If so connect to that also). Now, reverse the ohm meter leads and check those same wires again. You should get a reading in one direction, and none at all in the other direction.

Now, connect the black lead of the ohm meter to the red wire. One by one, connect the red lead of the ohm meter to the yellow, yellow/gray, and if present, the yellow/blue wire. Then reverse the leads, checking the wires again. Once more, you should get a reading in one direction and none in the other.

Note that the reading obtained from the red rectifier wire will be lower then what is obtained from the other wires.

Any deviation from the "Reading", "No Reading" as above indicates a faulty rectifier. Note that a rectifier will not tolerate reverse polarity. Simply touching the battery with the cables in the reverse order or hooking up a battery charger backwards will blow the diodes in the rectifier assy immediately.

 

[fishfeatures]

Re: rough idle and I have a question about the s. plugs

Not sure about the rectifier & will let Joe respond to that, but you might pull the #2 spark plug boot & cut 1/2" off the lead, reattach it. it could just be a bad electrtical connection at the boot.

Or it is possible that someone stripped the #2 spark plug threads & has Heli Coiled it. IF so sometimes this threaded insert does not ground well to the aluminum head & can cause erratic spark into the cylinder.

Lead is too short to trim anything offf it , I'll source 3 replacements just to rule them out.
And they are the original threads in the plug hole.

 

[fishfeatures]

Re: rough idle and I have a question about the s. plugs

That model should have the small three (3) wire rectifier. It has nothing to do with the ignition and can be tested easily as follows.

(Small Rectifier Test)
(J. Reeves)

Remove the rectifier wires from the terminal block. Using a ohm meter, connect the black lead of the ohm meter to the rectifier base (ground), then one by one, connect the red lead of the ohm meter to the yellow, yellow/gray, then the red wire (some rectifiers may also have a fourth yellow/blue wire. If so connect to that also). Now, reverse the ohm meter leads and check those same wires again. You should get a reading in one direction, and none at all in the other direction.

Now, connect the black lead of the ohm meter to the red wire. One by one, connect the red lead of the ohm meter to the yellow, yellow/gray, and if present, the yellow/blue wire. Then reverse the leads, checking the wires again. Once more, you should get a reading in one direction and none in the other.

Note that the reading obtained from the red rectifier wire will be lower then what is obtained from the other wires.

Any deviation from the "Reading", "No Reading" as above indicates a faulty rectifier. Note that a rectifier will not tolerate reverse polarity. Simply touching the battery with the cables in the reverse order or hooking up a battery charger backwards will blow the diodes in the rectifier assy immediately.

thaks Joe I'll test it later on and post results.

 

[fishfeatures]

Re: rough idle and I have a question about the s. plugs

rectifier was bust so got a new one.

prob with motor was that there was a bad fuel connector going from the tank to the bulb. Once i eventually discovered this the motor came to life, and now pulling off any lead results in a cylinder dropping.
thanks folks

 

[CharlieB]

Re: rough idle and I have a question about the s. plugs

If the carb linkage 'sync' is slightly off, the center cyl could be 'lagging' and not have much affect when the plug wire is pulled off.

Double check your carb sync.