Honda 8 again

[lexi]

In a previous post I mentioned this engine going for an hour or a day before cutting out at various throttle settings. It starts and idles immediately........until dropped into forward or reverse upon which it dies and then starts again. Repeat this for a bit and it will eventually take off no problem.

It sometimes will go all day or do it again five times that day.

With the sudden loss of power I thought electrical as all the fuel system had been stripped and checked. Got a S/H CDI unit with leads and substituted it ............exacty the same symptoms. Got the Kamasutra book out and there is a Neutral Switch in the circuit. Could this be a factor? Engine always cuts out in forward and reverse but will always start in Neutral. Anyway it had a nice film of oil on it so I cleaned it off and degreased it all.
Another thing I noticed was a nice shiny Stanley blade sitting against the gearchange shaft and neutral switch..........I wonder? Rather complicates the process of elimination. Will try it again this week.

Alex

 

[SK700]

I had similar symptoms with my johnson 5(6/7/8 all same). Hope this is not the same fault as you. I found that it would remain running if I increased the throttle a bit before selecting gear. After a few sails with having done this I was not able to get it to go run in gear at all. When I took the leg gear box this turned out to be the bearing of the gear selection had siezed.

 

[lexi]

Did you get it all running again?

Alex

 

[SK700]

taking it apart the casting was quite bad (10 years old) and had cracked so descided to go for a new engine

 

[lexi]

If engine does stop tomorrow I suppose leaving it in gear and trying to pull it with start cord may tell me if there is a prob in gearcase.

Alex

 

[SK700]

probably will have start in gear protection unless you can curcumvent it.

 

[lexi]

It does have the start in gear protection........that is the neutral switch I spoke of. It only stops you starting it by putting a metal plate across a magnetic switch, I was wondering if this being covered in oil could be relevant to the malfunction Idescribed in first post.
Thanks. Alex

 

[misterg]

[ QUOTE ]
If engine does stop tomorrow I suppose leaving it in gear and trying to pull it with start cord may tell me if there is a prob in gearcase.

[/ QUOTE ]

How old is the engine? (I couldn't find the previous post you referred to except one about the coil last October). Our old(ish) Honda BF8A won't start if it's in gear.

I *think* that the neutral switch is linked to the oil pressure switch - if the black box sees oil pressure, it ignores the neutral switch, otherwise the gear needs to be in neutral, or no spark. Does your engine have the (green??) indicator lamp that shows good oil pressure? What happens to this lamp when you have the problem? If it goes out suddenly ("like a light" ho ho...), your problem might be related to the oil pressure switch (loose lead, etc. not necessarily oil pressure). If the light gradually flickers out as the engine runs down, then I don't think this is the case.

A bit more information would help - does the engine die as you're putting it into gear? Or is it happily motoring along in gear when it dies? Does it just stop dead, or does it sound 'a bit funny' before it dies? - That sort of thing /forums/images/graemlins/grin.gif

Andy

edit: I doubt that the oil would make any difference to the magnetic switch, but the stanley knife blade might. As above, I think the neutral switch is a red herring, as it doesn't do anything once the engine is running. The lead from the black box to the oil pressure switch is yellow on the wiring diagram I have. The same diagram also shows an overheat sensor, but I've no idea where it is, or what happens once it's been activated. It may be a USA only thing, as that's where I D/L my manual from!

 

[lexi]

Wonder what the overheat sensor would do? Engine cuts out instantly. It Restarts instantly and will idle forever..........cutting out as you put it in forward or reverse. keeps this up until after 10 attempts at moving off it finally goes........for five mins or 5hrs Replaced oil switch last year as it failed. Ran it for a bit once I made sure oil pump was working. No idea how long that blade was lying in there. If it had shorted switch to earth.why would it always start in neutral?

Engine is 14 years old and like new. Freshwater use only.....oil changed at 50 hrs or twice a season. Green light works per normal.What next........ pulser or exciter coils?

Alex

 

[misterg]

[ QUOTE ]
If it had shorted switch to earth.why would it always start in neutral ?

[/ QUOTE ]

As I understand it, the logic is that if the engine is already running, it will continue to run whatever the state of the neutral switch (think about it - you can select F, R or neutral, and the engine is supposed to keep going!). Even if the switch has a fault that indicates the engine is in neutral when it isn't, this wouldn't cut the engine - you'd just be able to start it in gear. (On the wiring diagram I have, I think that both sides of the neutral switch go back to the ECU, anyway).

Following this logic, it's possible that the ECU doesn't 'know' that the engine is running and kills the spark when you shift out of neutral. I'm not sure where it gets this information from, but *think* it's the oil pressure switch. (Presumably you've checked for loose connections, or damaged cables that might be disturbed by the act of putting it in gear).

It doesn't just need the idle speed upping a bit, does it?

Andy

 

[lexi]

I think you are right about neutral start switch. I`m looking for a test procedure to carry out when engine kills itself. Maybe swop out ECU? Any thoughts on thermostat? Idling speed is ok. Have tried increasing revs as I slip it into gear. My friend has same model. The oil switch went on his and he runs it without it.......no probs. I ran mine for a bit when it failed although I now have a new one..........will keep at it. If you have any more thoughts Andy...

Thanks Alex

 

[Lakesailor]

I think you're on the wrong track here. I have a Honda repair manual and the neutral switch is in the circuit from the ignition switch to the starter solenoid. It doesn't appear to have any bearing on the ignition side at all. It merely isolates the starter if not in neutral.

My guess is the idle mixture and tickover settings are wrong. If too weak at tickover the engine will speed up so the idle speed may have been dropped to compensate. Although it will tick over, when you put load on it (engage gear) the mixture is too weak and it dies.

Try screwing the idle mixture screw fully home and then wind it out 1 and a half turns. Then adjust the idle setting (tickover speed) on the linkage until the tickover speed seems OK.
When you put it in gear the mixture should be strong enough to keep the motor running against the load you have introduced.

 

[lexi]

Thanks LS. Plugs are perfect colour. Mixture set as per manual. Tested it slightly rich then adjusted till smoke disappeared in barrel. Engine can die instantly at 3/4 throttle after running for hrs. Engine is manual start. thanks for response ............need all the ideas I can muster. I will go over mixture again.

Alex

 

[misterg]

[ QUOTE ]
Engine can die instantly at 3/4 throttle after running for hrs.

[/ QUOTE ]
...Hmm. I thought you said it was cutting out just as you put it into gear /forums/images/graemlins/confused.gif...What are the full symptoms?


(For Lakey /forums/images/graemlins/smile.gif:
[ QUOTE ]
Engine is manual start...

[/ QUOTE ]
So's mine, and the neutral interlock switch, and oil pressure switch (& indicator lamp) just connect back to a single 'black box' ignition module).

What is the serial number of the engine (letters & first few numbers)? Do you have an owners manual? If not, you might find a suitable one here

I suppose we've widened the scope to cover the fuel pump / muck in the carb, too...

Best give us a full description of what happens, and when. /forums/images/graemlins/ooo.gif

Andy

 

[Lakesailor]

Yup. Not getting full info here.
The BF8a motor has points and condensor?
The neutral start switch does not include the oil pressure circuit according to the wiring diagram. It does not short out to ground either so I assume it passes current in neutral and is open circuit in gear. You could test that with a test light or meter.
In which case join the wires and leave the switch out of the circuit. (remember the engine will start in gear) If it behave well in all circumstances, it's the switch. If not (as I suspect) it's nothing to do with the switch.
If it is a points and condensor igntion system, try a new condensor.

 

[VicS]

[ QUOTE ]
try a new condensor.

[/ QUOTE ] My experiences of failing condensers is that the engine becomes progressivly more difficult to start. Not that it cuts out once started but if the revs drop on engaging gear as they will that might be enough for a dicky condenser to play up. A CDI unit has been mentioned though so presumably it is a CDI ignition

Personally I would go with your ealier suggestion that the carb may need adjustment. The slow running setting if it has a separate one. Increase the speed a bit and enrich the mixture. Adjust the carb so that it runs properly not just to the book setting. That is just a starting point.

It could be that the carb especially the slow running jet/passages need cleaning.

Thinking about it though when I put my OB into gear I simutaneously open the throttle a bit.

 

[Lakesailor]

Well that was my thought but he says he has set the mixture as per.
I reckon the best way is still as I suggested, to remove the neutral switch from the circuit and try running it again. As long as it's done in the knowledge that it will start in gear, and just to prove or disprove the theory. If it is the switch, replace it. If not, move on having discounted that.

Similarly, and separately, remove the kill switch from the circuit. No particular reason it should be that, but once tested it can be discounted. Remember to reconnect.

Looking at the wiring diagram I see the oil pressure switch, although it goes to the CDI unit is shown as independant of the ignition. But I do notice there seems to be one HT coil for both cylinders.

He needs to work through methodically. Jumping about will only confuse the job.

 

[lexi]

Thanks Guys

Ser no.8AKLD BACL1102268
It`s got CDI.One main coil with two HT leads and one LT connection. I checked Pilot screw and it was 3 turns out.....plug colour is good.......lightish brown. I know that my Honda 5 is set at 1 1/4. Manual for 8 does not give a starting point but merely offers the procedure. If it was unscrewd farther out than it should be...... mixture would be richer? Would this not discount lean theory?

Like I say it can go for hours........cut out is instant no splutter of fuel or warning. I will be on Loch Lomond This weekend and try a few things out. Mind you I have seen it going for two days ..........Then die..... I have a B75 manual with a supplement for BF8.

Alex

 

[Lakesailor]

The idle mixture screw (they call it the Pilot screw) is an air bleed screw.
The spec is 2 1/2 turns out (found it in the book) so 3 turns is a tad weak, but not too far out.

But the cut-out when running sounds more like electrical. I hadn't realised it was a single coil. But I'd still bypass the neutral switch, then you can cross that one off.

 

[lexi]

I thought air screws were only used on two strokes?. My understanding was that a fuel screw weakens mixture when turned clockwise and an air screw does the opposite.

Will it suffice to pull bullet connections on Neutral switch and the same on kill switch.?

Alex