Johnson 4hp BJ4BREDS Idling Issue

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Steamonthewater

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Dear all,

My first post here, and I'm afraid it's one of those really annoying 'I know it's something simple, but I can't work it out' questions!

I run a traditional boatyard in the lake district and specialise in wooden launches and sailing vessels, as well as steam power.

A regular customer of mine who I trust and is a good friend asked if I'd accept two 4hp Johnson outboard as rent for boat storage, they had both been serviced before being stored for a few years in a dry loft- being experienced boaters I knew they would have been stored properly.

Anyway, I managed to sell one- only for the buyer to report it wouldn't come out of gear- a common issue on these if laid up for a while I understand. I said I'd take it and fix it, but they said they'd rather swap for the other one I had- trial runs had proved that this second one didn't want to run at all, and I took pains to stress this to the buyer.

Anyway, they took the second one, and hey Presto, it doesn't run!

I feel obligated to help, and have put a fuel pump service kit on at my own cost, but still finding that it will idle for around 10 secs then doe slowly. Pretty convinced it's still a fuel issue, the float chamber is filling Ok, and the lines and carb are all very clean. The plugs are the ones that it had installed before being laid up and are essentially new, no residue on them at all. Compression is very good.

I'm now resenting how much time this engine is taking up when I have other work I need to be getting on with, not to mention I hate outboard with a vengeance!

Any helpful suggestions would be most welcome!

Thanks,

Greg
 
This is an incredibly silly thing but happened to my similar BE4BREDS.

The plastic linkage that works the choke got partially disengaged. The result being that the choke was still operating despite the knob being pushed in.

It had an effect very similar to what you describe.

No parts needed for repair, just a matter of getting the little plastic bits into the right places.
 
Steamonthewater said:
Dear all,

My first post here, and I'm afraid it's one of those really annoying 'I know it's something simple, but I can't work it out' questions!

I run a traditional boatyard in the lake district and specialise in wooden launches and sailing vessels, as well as steam power.

A regular customer of mine who I trust and is a good friend asked if I'd accept two 4hp Johnson outboard as rent for boat storage, they had both been serviced before being stored for a few years in a dry loft- being experienced boaters I knew they would have been stored properly.

Anyway, I managed to sell one- only for the buyer to report it wouldn't come out of gear- a common issue on these if laid up for a while I understand. I said I'd take it and fix it, but they said they'd rather swap for the other one I had- trial runs had proved that this second one didn't want to run at all, and I took pains to stress this to the buyer.

Anyway, they took the second one, and hey Presto, it doesn't run!

I feel obligated to help, and have put a fuel pump service kit on at my own cost, but still finding that it will idle for around 10 secs then doe slowly. Pretty convinced it's still a fuel issue, the float chamber is filling Ok, and the lines and carb are all very clean. The plugs are the ones that it had installed before being laid up and are essentially new, no residue on them at all. Compression is very good.

I'm now resenting how much time this engine is taking up when I have other work I need to be getting on with, not to mention I hate outboard with a vengeance!

Any helpful suggestions would be most welcome!

Thanks,

Greg
Click to expand...
 
Have you cleaned out carb and set pilot jet?

This may be a quirk of my own Evinrude, but she at times wont idle for long either. Reseating HT leads and coil leads cures the problem for a season. And yes the leads are good. I.e check for weak spark at low revs.
 
BruceK,

I have cleaned the carb, but I'm not sure where the jet should be set to so I've left that where it is. When she fires up she runs lovely, but then chokes and the revs fall off then dies without so much as a splutter.

I wonder if you're onto something with the jet setting- but then I wonder why it starts ok and revs smoothly until after about 10secs. If it was the jet I'd expect it to run rough from the start and stay that way? Happy to be wrong though.

Greg
 
If you take the plugs out immediately after the engine dies, are they dry or wet?

Will it keep going with a wide open throttle but just not tickover for long?
 
James,

I haven't checked the plugs to see if they're wet- a good idea though.

It runs for a little longer with the throttle open, but does the same thing after maybe 15-20 secs.

Greg
 
Forgive me for returning to the choke.

With my outboard the starting position when cold is choke out, throttle wide open. Pretty well immediately after it fires the choke must be pushed in or it will die.

Are you quite sure that the metal spindle which goes into the side of the carburettor is turning when the choke is operated?
 
Steamonthewater said:
BruceK,

I have cleaned the carb, but I'm not sure where the jet should be set to so I've left that where it is. When she fires up she runs lovely, but then chokes and the revs fall off then dies without so much as a splutter.

I wonder if you're onto something with the jet setting- but then I wonder why it starts ok and revs smoothly until after about 10secs. If it was the jet I'd expect it to run rough from the start and stay that way? Happy to be wrong though.

Greg
Click to expand...

Run engine until warm with jet screwed in then backed off two and a half turns. Start with the pilot jet screwed three turns out. Adjust (tighten) until peak idle revs are reached and then descend (leaned out). Go back to peak revs then back off a quarter turn. That should put you as close as dammit without diagnostic kits.

Steamonthewater said:
James,

I haven't checked the plugs to see if they're wet- a good idea though.

It runs for a little longer with the throttle open, but does the same thing after maybe 15-20 secs.

Greg
Click to expand...

However if this is happening also at high revs (full throttle) discard above. I would suspect the float bowl is leaning out. Check float height, after taking needle and seat out. I cant be sure on yours but often there is a gauze filter above the needle and seat and if this has blocked up with crud could be your problem. Check the flow of fuel is not impeded from pump to carb bowl.
 
Last edited:
If it's starting ok then it's likely one of two things, either the choke or the mixture setting which is the small screw right in the middle next to the choke. The choke lever is also the fuel cut off so you have checked that it's turned the right way? But I guess it's likely the choke sticking out as you should start these with choke out always and almost immediately push it in. Lovely outboards even when in relatively poor health.
 
Thanks all,

It isn't the choke, I'm testing with the cowling and air intake off so controlling everything by hand and can see what's going on, the choke works fine, as does the fuel valve.

Bruce, I think your suggestion of the float could be worth checking out, I'll check the plugs and see of they're wet after it dies and check the float height.
 
As mentioned and if you haven't tried...mess with lean/rich adjustment on the front of the engine.
Having just acquired a similar evinrude, I had to do the same. Still no idea what the orange twist/turn knob is for under the cowling and next to flywheel is thoigh !
 
Second the choke/fuel on off knob too. Unlike any other outboard this size. The choke and fuel off/on switch are the same knob. Perhaps you know this thoigh.
Best starting is to pull choke out, pull at starter (she'll try and fire) then quickly grab at revs and put choke off.
Really impressed with these wee engines. So light and really smooth with the 2 pots.
 
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