My 1994 johnson 225 back fires/ sneezes at idle

[levi_tsk]

My engine backfires at idle just a loud POP and then it will idle fine for a couple seconds and repeat I found a YouTube video showing the same situation and it was a loose hose on the inlet side of the vro pump?
Could it be the vro? its been deleted or bypassed but I'm not sure its been done properly? are there things I can check to make sure it has been done properly?

I'm very unfamiliar with the whole VRO system but pretty good with my tools, carbed two stroke outboards and problem solving just need to know where to start besides getting a manual (its on it's way)

I just bought the boat today and it sat for two years until Friday the previous owner rebuilt the carbs Sunday supposedly ...
If I do a drop test pulling the plug wire on the #4 cylinder makes it stop backfiring idles normally when I pull the plug wire but it sounds kinda high though (Lean maybe?)

looking at the back of the motor here's a diagram (not sure if I got the cylinder # right or not so this will save some confusion)
-----------------2 1
this plug ----> 4 3
---------------- 6 5

this is on the hose btw and ill post the model number in the am when I get home tomorrow morning

Thanks ahead of time !
Levi

 

[Bosunsmate]

Re: My 1994 johnson 225 back fires/ sneezes at idle

Maybe your reed valve for that cylinders gone
have you a model #?

 

[Faztbullet]

Re: My 1994 johnson 225 back fires/ sneezes at idle

You cant tell anything on a hose, stick it in a barrel as it has to have back pressure to idle correctly. Also remember this is a X block and carbs on port side feed starboard cylinder s and vise versa

 

[daselbee]

Re: My 1994 johnson 225 back fires/ sneezes at idle

You probably have the orange primary wires for coil #2 and coil #4 swapped. Check it to be sure! Orange/blue stripe is always top coil, orange is middle, and orange/green is bottom coil. This applies to both sides. The thing that makes me think this is the problem is that you can stop the backfiring by removing #4 plug wire.....hmmmm.....

 

[levi_tsk]

Re: My 1994 johnson 225 back fires/ sneezes at idle

that's gonna take a BIG barrel Big trashcan work do think Faztbullet?
the model number is : J225PXEIC so it is a 1991 right? I was only going by what I was told :/ does that change anything?
thanks for the responses btw !

 

[levi_tsk]

Re: My 1994 johnson 225 back fires/ sneezes at idle

Can I swap the reeds from one cylinder to another and see if it moves? Also when I pull it is there a way to tell if its bad or not?
Are they carbon fiber or brass reeds?

 

[daselbee]

Re: My 1994 johnson 225 back fires/ sneezes at idle

Man, why are you going for the most difficult "fix" first? Look at the easy stuff first. Did you check the primary wires?

 

[levi_tsk]

Re: My 1994 johnson 225 back fires/ sneezes at idle

Yea sorry daselbee I didn't see your response ill check your suggestion first here in just a second thanks a TON!!

 

[Bosunsmate]

Re: My 1994 johnson 225 back fires/ sneezes at idle

You can put your hand just in front of the carb for that cylinder and see if you feel any back draught against your hand and if its different to the others. It might spit a bit of fuel out too

yes thats a 91 model

 

[levi_tsk]

Re: My 1994 johnson 225 back fires/ sneezes at idle

ok so heres what I found out so far :
The power pack is wired up properly
it was throwing a little fire out through the carb when it was doing the backfire thing
it doesn't do the backfire thing when its ice cold and only begins to do it a couple mins after the thermostat opens.
Any ideas ? The guy I got it from said he thought it was a reed valve going bad and he is a mercury mechanic I found a pair of reed blocks for $36 bux from a guy I've bought parts from before for my other motors so he's reputable

Thinking about swapping out the reed blocks to another cylinder any thoughts against that?

 

[Faztbullet]

Re: My 1994 johnson 225 back fires/ sneezes at idle

Doubt it reeds ,possibly a reed block gasket as this is common on these motors or throttle plate not closed..

 

[boobie]

Re: My 1994 johnson 225 back fires/ sneezes at idle

I'll go along with the reed block gasket as I've seen it happen before. Or a double firing pulse pack on that cylinder which can also cause spit back.

 

[daselbee]

Re: My 1994 johnson 225 back fires/ sneezes at idle

+1 for the "not the reeds" diagnosis. But go ahead and change the block anyway. You will learn firsthand what a big task that is.

 

[boobie]

Re: My 1994 johnson 225 back fires/ sneezes at idle

I think you should check the double firing first. That is the simplest to do.

 

[Faztbullet]

Re: My 1994 johnson 225 back fires/ sneezes at idle

If you go for the reeds/reed block note where the manifold bolts are removed as some are a tad longer than others and several will have a dab of sealer on them

 

[levi_tsk]

Re: My 1994 johnson 225 back fires/ sneezes at idle

+1 for the "not the reeds" diagnosis. But go ahead and change the block anyway. You will learn firsthand what a big task that is.

YEP QUITE the task !!! I went head and did it for my own piece of mind ... new gaskets for them will be on my way the reeds on the #4 cylinder were pretty dirty but I took it to the mechanic down the street and he said they were fine im gonna clean them with a little carb cleaner just to be safe though but you were right daselbee I know you know your stuff buddy so thank you for trying to steer me away from that direction but I'm hard headed...

Faztbullet while ive got it apart is there a gasket between the reed block and the intake manifold itself? the gaskets between the throttle plate and the intake manifold looked pretty rough so I ordered all of them and ill be replacing them today also after talking with the head mechanic at my local shop he also said to check that the throttle plates are closing fully on that cylinder too so once its back together ill check that he said if it out of wack it will ring when the throttles closed and I tap on the plate also said for $85 he diagnose it if I couldn't fix it so I might go that route if all else fails

also yea I took the bolts out and kept track of which ones went where and threaded them back into the manifold and into each's respective holes and ill reassemble the ones that need it with new sealant would silver rtv work or?



Boobie ? would the double firing thing be pretty obvious with a spark checker at cranking speed or? wondering if I should warm up the motor before I check that or? wait for it to start back firing you know? that would be the power pack causing the double firing situation right? bum diode in it or something ? Its a CDI one but I was looking through the receipts that came with the boat so it could be bad ...?

While ive got it apart im going through the carbsagain for my own personal satisfaction I ordered new gaskets for between the throttle plates and the carb bodies too so those will be replaced so far the carbs look pretty clean even in the idle air bleeds I would like to verify that the bleeds marked 46 go in the top hole and the bleeds mark 36 go in the bottom correct?

Thankyou guys for all the responses and keep em coming cause so far I haven't found anything yet..

 

[boobie]

Re: My 1994 johnson 225 back fires/ sneezes at idle

Take the spark plugs out and get each cylinder at top dead center. Then use a white marker and put that cylinder # on the flywheel. After that you put the plugs back in and start it up. Use a timing light on each cylinder and if another cylinder # shows up, it's double firing. The pack is usually the culprit. Check this when the problem shows up.

 

[levi_tsk]

Re: My 1994 johnson 225 back fires/ sneezes at idle

Ok thanks Boobie !!!! yea I forgot to put in that it was changed in '06 according to my receipts so it could be bad

well I finished cleaning the carbs I did find that one of the carb floats was set too low in the bowl and that may have been the culprit but I'm gonna run Boobie's test once I get it back together tomorrow it's trying to rain and I don't wanna be assembling important parts if its wet out

I'm also changing out all the fuel lines to the carbs, fuel pump, and to the tank and maybe that could've been the problem as well and if not it's one less thing to be worried about they were pretty old and looking kinda tired...
I'm also changing the reed block gasket on that cylinder while its apart it's cheap insurance and that may get it too I broke it trying to get it out but I couldn't see trying to put it back together without checking it its a $3 part and buried deep ....
I've pretty much run out of things to check besides Boobies power pack thing and the throttle plate I've got a spare coil and I may try one of those if nothing else shows up
Once again I REALLY appreciate the help and the wealth of knowledge available here so thank you guys!!

 

[daselbee]

Re: My 1994 johnson 225 back fires/ sneezes at idle

Something is not right. Go to shop.evinrude.com, look for your motor, look at the carb pages, and compare orifice sizes. Items #3 and #5 on the drawing. Looks like a carb tinkerer has been at work.

 

[daselbee]

Re: My 1994 johnson 225 back fires/ sneezes at idle

So, you got it apart, and are waiting on parts? Is that the status right now? If so, here are some tips in re-assembly: 1. Reed block gasket is a long rectangle. The "long side" of that gasket tends to squish out , or bulge out, after you install the 4 screws that attach the reed block to the intake. It doesn't squish at that moment. It waits until you have it all back together, then it squishes out:joyous:. I always use an adhesive to glue that gasket on better before assembly. I use 3M yellow weatherstrip adhesive very lightly, wiping up any excess if it oozes out. The symptoms if it squishes are this: Massive gas raining out the front of the carb when running. Just remember which reed gasket you replaced, and if that carb is raining gas out, then reed block gasket has squished out. 2. On that intake....I forget which screw it is.....but there is ONE screw that has interference with the casting of the intake, that you cannot get a socket on. You have to assemble that screw first, before you , say, put the upper intake on (or lower) I forget which....but there is one screw that is a PITA. It is lower center either on the upper intake or on the lower intake. If you don't do it first, you will have to remove everything you just assembled just to get to it to put it on and torque properly. PITA. 3. You may not think about this, but once you remove and then re-assemble the throttle bodies, you MUST re-sync the throttle butterflies. Just the simple R and R of those bodies, can, and usually does, throw the butterflies out of sync, most often a butterfly will be slightly open on the bottom two cyls. Sync the throttle plates/butterflies with the black carb bodies OFF. You can see the whole thing way better. All butterflies must be completely closed, and operate in exact sync with each other. Perfection is critical here for proper idle.