87 140hp Johnson Intermittent problem

[WB2RNA]

First start of day, engine fires but idles very rough. Smoothes out after warming. Underway, as throttle is advanced, a point is reached where engine stumbles, reduce throttle and engine smoothes. Throttle position where stumble occurs gets higher and higher as engine warms. Eventually full throttle can be achieved without stumble. However, once under full throttle engine may stumble, as if driver quickly pulled throttle to idle. Actually pull throttle back, troll for a bit and return to full throttle w/o problem. It may do this a couple of more times, but eventually it would always start run OK for remainder of day. This season however, it appears the problem is less intermittent, as I have only reached full throttle a couple of times.<br /><br />Verified all fuel and oil hoses to and from VRO unit are tightly clamped.<br />Charge, sensor and all 4 ignition coils are within spec using ohmmeter. All contacts/connectors cleaned.<br />Have not performed flywheel index test or any test requiring CD Voltmeter. I do have factory service manual, but no CD test gear.<br /><br />What are the odds it is the Power Pack???

 

[Hooty]

Re: 87 140hp Johnson Intermittent problem

What are the odds it's a powerpack? 50-50. <br />If you can get it to do it's little stutter step on the hose, you can use a timing light and see if it misses a beat or not. Something else you might try is give the primer switch a real quick jab. It has to be quick because you don't want to flood it, just enrichen it. If it clears up, ya got a fuel problem.<br /><br />c/6<br />Hooty

 

[WB2RNA]

Re: 87 140hp Johnson Intermittent problem

When primer is 'hit', stumble momentarily worse. Plugs are WET with gas when removed and examined when problem is occurring. I am going to gamble and order a power pack. Will post results.<br /><br />Jim

 

[Hooty]

Re: 87 140hp Johnson Intermittent problem

'kay, be sure and lettus know what happens.<br /><br />c/6<br />Hooty

 

[WB2RNA]

Re: 87 140hp Johnson Intermittent problem

Well, I lost the gamble. The new power pack did not fix the problem. I have some new data about the problem however. One of the ignition tests outlined in the service manual is to use a timing light to verify the correct cylinder is firing at the correct time. In my case the correct cylinders are firing, but not all the time! Based on the strobe flashes it appears that all cylinders are not firing all the time. The strobe has periods where it does not fire. A cylinder may fire OK a couple of times, then miss a couple of beats, then fire again a couple of times. This occurs on all 4 cylinders. Based on this, the problem must be under the flywheel... job now is to determine if it is STATOR, SENSOR or the flywheel MAGNETS. Stator creates the voltage for spark, sensor triggers spark at correct time, and magnets generate the voltage in both sets of coils. Could be any of these components. By the way, resistance tests of the stator and sensor coils are all within spec. Have not done peak voltage tests, but don't know if doing them would help determine problem. <br /><br />Whats the vote on the failing component???<br /><br />Jim

 

[Walker]

Re: 87 140hp Johnson Intermittent problem

Okay, try this. Pull flywheel and clean crankshaft and flywheel where they mate.

 

[Joe Reeves]

Re: 87 140hp Johnson Intermittent problem

Jim.... If anything's been mentioned about compression and spark, I've overlooked it. That should be the first tests made regardless of any problem.<br /><br />The spark plugs should be Champion QL77JC4 plugs, gapped at .040. In removing the s/plugs, they should all look alike, do they? Describe their appearance by cylinder number.<br /><br />Check the compression and make note of the readings via each numbered cylinder. What are they?<br /><br />With the spark plugs out, the spark should jump a 7/16" gap with a strong wide blue lightning like flame.... a real strong snap! Does it?<br /><br />Check the stator for cracks and a possible oozing of a sticky substance which would drip down on the block and the timer base area. If this exists, that would cause a AC voltage drop from the stator to the powerpack, which in turn would result in erratic and eventually no ignition (spark).<br /><br />The above last paragraph (problem) would also result in a sticking timer base (retarded spark).<br /><br />Let us know what you find.

 

[kevin Ron]

Re: 87 140hp Johnson Intermittent problem

I have a very similar problem with my 95 175 if you figure it out plkease drop me a line.<br /><br />Thanks

 

[kevin Ron]

Re: 87 140hp Johnson Intermittent problem

I have a very similar problem with my 95 175. If you figure out your problem please drop me a line.<br /><br />Thanks

 

[WB2RNA]

Re: 87 140hp Johnson Intermittent problem

Latest info... Looked at spark w/7/16 inch gap. One cylinder had a fairly consistant spark, but it was not a nice wide spark and did not make a loud snap. On the other cyls I saw a very intermittent weak spark. Tough to see. I do not have a peak reading voltmeter, but using a digital meter reading AC volts, the voltage out of the stator was only around 50, with is probably RMS or an average reading which I feel is too low. Going to see if I can scrounge a peek reading meter or adaptor and look for the 175 volts specified. Looks like its zeroing in on the stator coil. Took the flywheel off and inspected the stator coil. Looks almost new, no burnt or melted areas. Ohm meter test is within spec. I did however, get a bit of voltage from both stator leads to ground using my digital volt meter... the reading jumped around, not a stable reading, but there was someting there. This would indicate a leak to ground in the stator coil. <br /><br />Another problem I have is that the tach drops to 0 rpm when engine rpm is above approx 2000 rpm. This has not affected running in the past. It is curious however, as the stator has both the ignition charge coil and the alternator coil which supplies the tach voltage.<br /><br />Spark plugs are brand new QL77JC4's set to .040. They are wet with a bit of black soot on them. All plugs look the same.<br /><br />Does this info help narrow down the problem at all?<br /><br />Thanks, Jim

 

[Joe Reeves]

Re: 87 140hp Johnson Intermittent problem

Jim... Do another spark test as follows. Disconnect the large RED electrical plug at the engine. Remove the s/plugs and rig the 7/16" tester. Crank the engine via the solenoid with a small jumper from the battery term of the solenoid to the small 3/8" nut that activates the solenoid (not the 3/8" ground nut).<br /><br />If you now have proper spark, replace the ignition switch.<br /><br />I don't have any faith in the above test to cure your problem but it's a test that should be done just in case you have a dual problem (stator & switch).<br /><br />The explanation of results you gave of the previous spark test and the readings that you received from the stator.... if you've double checked those readings and they still hold true, I'd replace the stator.

 

[WB2RNA]

Re: 87 140hp Johnson Intermittent problem

Lost another bet... New stator did not correct the problem. Engine starts without any problem, but is still running rough and more throttle to increase idle speed has little or no effect.<br /><br />Removed the hi voltage lead between ignition coil and spark plug on cyl #1. Engine ran no differently, which surprised me. Replaced #1 and removed #2. Same result for all cylinders. Runs the same on any 3 cylinders as it does with all 4<br /> <br />Just did the spark gap test with the large red plug disconnected and could only see the spark on cylinder #3. Sun is bright where I am working, so other cyls may have fired once in a while, but I could not see or hear it.<br /><br />I have replace these components:<br />spark plugs, plug wires, power pack, stator<br /><br />Only remaining possibilities:<br />Timer base, ignition coils (4), flywheel (magnets)<br /><br />While it is possible that multiple ignition coils are failing, the odds would be against it. And do magnets get stronger with temperature? <br /><br />In the past, when the problem would fix itself, it would be as if a switch was flipped... instant. And if I did get to full throttle, it sometimes would fail just as fast, like the key was turned off, but it would still be running. Backing off throttle and then accelerating again, it would run OK. Once fully warmed up it would be OK for the rest of the day. <br /><br />What would be my next move? I am getting very discouraged. It must be under an evil spell. <br /><br />Thanks, Jim

 

[Fl_Richard]

Re: 87 140hp Johnson Intermittent problem

In the past, when the problem would fix itself, it would be as if a switch was flipped... instant. And if I did get to full throttle, it sometimes would fail just as fast, like the key was turned off, but it would still be running. Backing off throttle and then accelerating again, it would run OK. Once fully warmed up it would be OK for the rest of the day... Sounds EXACTLY like what I'm experiencing with one of two 1995 (NOT Ficht) 150 Johnsons. <br /><br />Anyone know what the final resolutlion was here?

 

[OBJ]

Re: 87 140hp Johnson Intermittent problem

Jim, if the sync and link are good, I think ya' got some junk floating around in one of the float bowls or the carbs just need a good over haul. The bowls are plastic, do you notice any leaking around the float bowl gasket area when the primer bulb is pumped up snug?

 

[Sherman]

Re: 87 140hp Johnson Intermittent problem

hi Jim<br /><br />Have you made any more progress on this problem. I have been fighting this situation for a couple of years with no luck. I took it to the dealer, still no luck. If you find out anything more please let us know.<br /><br />Thanks<br />Sherm