J30JRSIE 30 hp Outboard - Carb Question

[1hook]

Hi all,

I have a 30 horse Johnson jet that is having some run issues. JS30JRSIE. It starts and idles fine but when I try to throttle up it doesn’t always want to. It will come in and out of acceleration. It accelerates up to speed and will run at full speed and then will just bog down. Then it will come back out of it and run full speed. Sometimes I can’t get it to accelerate at all. Sometimes it will run at full speed for a mile.

So I was thinking I likely have some carb issues and that would be a good place to start tinkering. I have taken apart many small engine carbs, but I have never fiddled with dual carbs.

Upon taking the engine cover off to get a feel of what I was about to get into I right away noticed that the top carb is missing what appears to be an orifice plug… picture attached.

Is there any chance that is intended to be that way or am I clearly missing that plug?

I do have the service manual ordered but will be a bit till it ships. I wanted to dig into the carbs and get parts ordered if needed.

Thanks for your help!

 

[saltchuckmatt]

Looks like your missing part number 9

https://www.marineengine.com/parts/johnson-evinrude-parts.php?year=2001&hp=30&model=J30JRSIE&manufacturer=Johnson&section=CARBURETOR

 

[1hook]

Thanks for the reply, I just wasn’t sure if for some reason that top carb was meant to not have that in there.

What purpose does that plug serve? Would there be a reason someone would have removed it?

 

[saltchuckmatt]

Just an orifice....so not sure, guess would be for another application or a cleaning function.

Plug it up and see how she runs....be sure to clean your plugs first.

Good luck

 

[racerone]

It has a calibrated hole.-----Lets a certain amount of air in.---Order the correct part.----No reason why anybody left it out.-----Perhaps they lost it.

 

[jimmbo]

Before you go ripping the Carbs off, see if you can get a replacement Orifice, install it and if the Problem(s) is solved. Might save you the Hassle of having to do a complete Link and Sync.

 

[tphoyt]

If you can afford it get a couple of the plastic tops to. You will likely need them some day.
The last time I had to get them it took 3 weeks.

 

[1hook]

Before you go ripping the Carbs off, see if you can get a replacement Orifice, install it and if the Problem(s) is solved. Might save you the Hassle of having to do a complete Link and Sync.

That’s a good call, think I will start there.

Now let me ask you this. If I take the carbs off and clean them and don’t mess with any settings… put it all back together as it was.

Am I able to do that without throwing things out of wack? I know that’s counting on it be set up correctly to begin with. The boat ran good the previous year.

 

[1hook]

Ha! Just found that part sitting in the bottom of the engine! Must have vibrated out.

 

[saltchuckmatt]

Simple answer is "no"

 

[racerone]

Put the jet back in and test run.

 

[tphoyt]

That’s a good call, think I will start there.

Now let me ask you this. If I take the carbs off and clean them and don’t mess with any settings… put it all back together as it was.

Am I able to do that without throwing things out of wack? I know that’s counting on it be set up correctly to begin with. The boat ran good the previous year.

If you remove both carbs at the same time and then remove the side link to separate them and not mess with any screw settings it can be done. But it’s always best to go through the link and sync process just to be sure.

 

[1hook]

Just to follow up, I got the boat in the water today and that unfortunately did not solve the problem so I need to keep troubleshooting. The motor starts and idles fine but at full throttle doesn’t go very fast. I can only go about 5 mile an hour at full throttle. Previous year I had no issues getting to full speed in the motor Responded fine to throttle inputs.

 

[saltchuckmatt]

Take the air box cover off, with the engine off, put it to full throttle and send us a picture of the inside of the carb. (Butter fly valve)

 

[racerone]

Does spark jump a gap of at least 3/8" on both leads ?-----Post the actual compression test values.

 

[1hook]

Hey guys I will follow up on both of these posts. I don’t have a compression tester at the moment though.

I was wondering if I had lost spark possibly on a cyclinder and was gonna check that out.

I’m headed out of town for a few days so I won’t have a chance to mess with it for a bit.

 

[1hook]

Ok sorry about the delay. I have not been able to fiddle with this until today.
I decided to first start dealing with spark, it just seemed like it was only running on one cylinder. I took the boat down to the river and hooked up my inline spark tester and was able to see that I had spark on both cylinder. I got Home pulled both plugs and they appeared fine, I decided to get my multimeter out to test them and they seemed good.

Thinking all is well but deciding to do one more test I threw one onto my snowblower spark plug boot and crank the engine over to watch for spark.

One of the plugs will spark one of the plugs will not , so I am thinking that I lost spark on a cylinder due to a bad spark plug. My question now is; everything seems OK on that spark plug but it will not fire at all. The gap seems good. It looks OK. Either way I’m getting two new spark plugs today and then we’ll go test again .

What could cause that spark plug to fail when I test from end to electrode tip it tests out at around 4000 ohms. Doesn’t show a reading anywhere else on the plug.

I guessing somewhere it’s leaching spark.

 

[saltchuckmatt]

Re-read post 15.....

Your barking up the wrong tree....

"Spark JUMP test"
"Compression"