2006 90hp johnson fuel issue?

[gahunter706]

I recently bought a new to me boat with a 2006 90hp johnson. It seems to run great, other than what seems to be it not getting good fuel at 3/4 to full throttle. Its not a constant thing, but every couple of minutes when riding it will act like it is misfiring or running out of fuel, and then pick right back up to running fine. I plan on changing the spark plugs, fuel lines and water/fuel separator filter. Does this seem like a good starting point for the issue? Also, does anybody have a recommendation on the best plugs to run in this motor, and possible a service manual for it? Thanks.

 

[gahunter706]

I just went and pulled the plugs, and they look fine. Nothing that I think would cause this issue, although I think I will still change them.

 

[schematic]

multiple models of that year. need model number.

 

[gahunter706]

multiple models of that year. need model number.

I will get the number posted when I get back home. I replaced the fuel lines, bulb and filter. I found quite a few cracks in the old lines so I'm hoping the new lines will fix it. Headed to the lake right now to test drive it.

 

[gahunter706]

Well I don't think the new fuel lines fixed it. When I took it to the lake it ran fine for about the first 10 mins, and then started occasionally misfiring like it was before. I'm not sure which number is the model number, but I believe it is the one that says engine family on the plate on the outside of the motor. That number is BBCXM0105210.

 

[jakedaawg]

Nope, its gonna say J90PL4SD or something like that. Need that number for these guys to help

 

[Chris1956]

Check the antisiphon valve in the built-in fuel tank, as well as the fuel tank vent for clogs. 3/8" ID fuel lines and fittings (fuel tank, water separator, primer bulb) should be plenty large. 5/16" fittings might/might not work.

 

[gahunter706]

Nope, its gonna say J90PL4SD or something like that. Need that number for these guys to help

Ahh ok. Where will this number be located at?

Check the antisiphon valve in the built-in fuel tank, as well as the fuel tank vent for clogs. 3/8" ID fuel lines and fittings (fuel tank, water separator, primer bulb) should be plenty large. 5/16" fittings might/might not work.

The fuel tank, lines, bulb and water separator are brand new, and the fuel lines are 3/8". The problem was there before the new tank though, and I only changed the tank to go to a larger one.

 

[Chris1956]

Some Antisiphon valves have screens on them. They can get partially clogged, from debris in the fuel. your fuel tank vent is working?

 

[jakedaawg]

Model number is on engine bracket or transom clamp, whatever you want to call it

 

[gahunter706]

Model number is on engine bracket or transom clamp, whatever you want to call it

I can't seem to find it anywhere on the bracket. It looks like there is three stickers that would possible have the number on it, but the only one that has anything visible on it is the emission control sticker. And the info on that sticker is barely visible. Is the model number located anywhere else like on the block?

these two stickers are on the port side of the bracket



this one is on the starboard side



and this is what the spark plugs looked like when I pulled them. They look fine to me but I figured I would get yalls opinion on them.

 

[gahunter706]

Any thoughts on this?

 

[jakedaawg]

These problems you list could be either fuel or ignition. You could have a weak pump (discounted because it runs at full throttle), partially clogged ports in the carb/carbs, a fuel restriction.....You could also have a powerpack or other ignition component starting to fail. Without being there and hearing said issues its tough to know what to concentrate on so lets start at the beginning.

1. Compresssion test. Done with the plugs out. Many auto parts stores will loan or rent a Quality compression gauge.
2. Open air gap spark test set to 7/16". Preferably one that will test all four at once. You want nice clean blue spark with a snapping sound. I would check spark while you are having the issue if possible.
3. Fuel sample. Look at the fuel in a clear jar. You are looking for water or "phase separation"
4. Plumb a length of clear vinyl hose in to the fuel line right at the fuel in nipple of the OMS pump. Your looking for air bubbles when running. Also tee in a Vacuum Guage and report in/Hg.
5 While issue is occuring you could do a cylinder drop test. Run boat till you have issue, then useing insulated plastic pliers pop one plug wire off at a time and see if you notice a change.

 

[jakedaawg]

Another thought, try running with the hood off. The older ones had an issue with the cowl latch grounding out a plug.

 

[gahunter706]

These problems you list could be either fuel or ignition. You could have a weak pump (discounted because it runs at full throttle), partially clogged ports in the carb/carbs, a fuel restriction.....You could also have a powerpack or other ignition component starting to fail. Without being there and hearing said issues its tough to know what to concentrate on so lets start at the beginning.

1. Compresssion test. Done with the plugs out. Many auto parts stores will loan or rent a Quality compression gauge.
2. Open air gap spark test set to 7/16". Preferably one that will test all four at once. You want nice clean blue spark with a snapping sound. I would check spark while you are having the issue if possible.
3. Fuel sample. Look at the fuel in a clear jar. You are looking for water or "phase separation"
4. Plumb a length of clear vinyl hose in to the fuel line right at the fuel in nipple of the OMS pump. Your looking for air bubbles when running. Also tee in a Vacuum Guage and report in/Hg.
5 While issue is occuring you could do a cylinder drop test. Run boat till you have issue, then useing insulated plastic pliers pop one plug wire off at a time and see if you notice a change.

Thanks for the suggestions. I think I figured out most of the problem, and it was the water fuel separator. I went to the water yesterday and went to pump the primer bumb and noticed that the filter had fell off. The threaded insert that the filter screws on to had pulled out. So I bypassed the water fuel separator and took it out for a long, probably 45 min ride and it only misfired twice, whick is way better than before.

 

[gahunter706]

Never mind, took the boat out today and it was pretty bad again. It runs fine if I cruise at about half throttle, but past that it will misfire. I did notice that it seems to do it worse when I hit the gas from half to full throttle, and the same when I go from full throttle to half. When I got home I pulled the cowling off and found gas on one of the carburetors, it looked like it was leaking from one of the gaskets. Maybe I need to rebuild the carbs?

 

[gahunter706]

Ok so I was looking at the motor Monday and decided to check the fuel filter on the motor. Took it out and it had some debris in it, but nothing too bad. I will still probably replace it though. But what I did notice was the gas that came out when I took the filter off was orange. Any idea why this might be? I pumped some gas out of the fuel line with the bulb and the first couple of pumps were orange gas, then back to normal color. It was 87 octane ethanol fuel if that makes a difference, maybe I need to start running non ethanol. Also, I found a crack in the plastic on what I think is the air inlet on one of the carbs, the same area that I noticed gas residue in. I assume this piece needs replacing, but would like yalls thoughts on it. Thanks for the help.

here is the orange gas



this is the crack. in the second pic I circled where it is on the motor

 

[racerone]

That crack would be on the float bowl.----Nothing to do with air inlet either,--Fuel sits in the bowl !-------This may be caused by warped float bowl and over tightening of those screws.----Me thinks it is time for a full inspection / cleaning of carburetors.

 

[gahunter706]

That crack would be on the float bowl.----Nothing to do with air inlet either,--Fuel sits in the bowl !-------This may be caused by warped float bowl and over tightening of those screws.----Me thinks it is time for a full inspection / cleaning of carburetors.

Yeah I haven't ever really messed with carbs before so I wasn't exactly sure what I was looking at. I will try to pull them off this weekend and clean/inspect them. There will be one for each cylinder right?

 

[racerone]

Exactly ---one carburetor feeds only one cylinder.