2000 Johnson 250hp - fuel delivery problem...really need some ideas.

[Cummins]

Ever since I've had the boat\motor ( 3 mons. ) it's not run good - acted like fuel starvation - sucking air..etc. Wouldn't idle good - hard to start ( hard to get primed ) etc.... It'll run good for few hrs. then it won't run.


When I bought the boat\motor the oil injection system had already been disabled and the I thought the VRO part of the fuel pump had been sealed off properly.


I resealed the VRO part of the pump - replaced the primer ball - replaced fuel lines from tank to fuel pump - new Atwood fuel filter - new Atwood fuel\water separator filter - new plugs - drained all carb bowls ( no trash ) - de carbed the engine - checked the compression, they're all within 10 psi of eachother and all in the 108 to 115 psi range.

Took the boat off shore two weeks ago - ran fine @ WOT for 2.5 hrs. getting offshore and ran good anything above 8 mph.... Anything below that speed, it didn't want to run - you'd have to pump the ball to get it to stay running. It would troll speed for a couple mins then you'd have to pump the ball again. On the way in it ran WOT for 2 hrs....not a problem. Got to the ramp to load the boat and it starts not wanting to stay running ( pump the ball again. ( Note: prior to taking it offshore I had taken it to the lake the week before it ran great all day - no problems. I thought I had fixed the problem with a single thing I had done or a combination of things - I was wrong ) A real pain in the butt.

Pulled the trigger on a new non VRO fuel pump last week. Took the boat to the lake today. Ran the boat for 1.5 hrs at all speeds - boat ran great - boat tied to dock for 45 mins. - ran down the lake for 15 mins..boat ran great. Boat sat for 3 to 4 hrs.. Could hardly get the motor to start after sitting for the 3 or 4 hrs. - couldn't seem to get it primed - when I did get it started it would cut off when you gave it trottle. It never ran good the rest of the day - it would hardly run at all.

Obviously the fuel pump isn't\wasn't the problem - waste of time and $$$$. This problem, what I think is a fuel problem has been going on since the first of April. The carb. fuel lines look good but I guess I can replace them also. I've checked and rechecked for cracks in vac and fuel lines...I've not found a bad line yet. Could be a crack in a plastic male nipple somewhere.


Any ideas would be greatly appreciated at this time...I'm at the end of my ideas. It runs good then it doesn't want to run at all. After the new fuel pump and after the first 1.5 hrs it seems to run worse than ever.

Ideas...?

[Dunk]

Well I would still check all the fuel lines under the engine cover. Pull a couple off and scrape the insides to see if maybe E10 is eating them..

But it sounds like you've got the fuel system right if it will run fine part of the time. I'm thinking you might have a power pack that going out. Sometimes when after they warm up they will show problems, but that doesn't seem to be your case. But they can still do weird things at different times.

When it won't start have you ever pulled the plugs and checked it for spark??

Actually your fuel/oil pump system is called an OMS system, not a VRO. Oil Metering System.

When you turn the key on do you get all the lights lit on the Systems check gauge or tach?? Then they should go off one at a time. Does this happen??

Do you have water separating filter?? Racor? If so are you getting any water in it?

[54bullwinkle]

Test your fuel lines first. Sounds like you are pulling air. Check the lines from the tank up, if you have an external filter or water separator, check that too. Make sure spin on filter gaskets are sealed with a little oil

[Cummins]

54....I've used a remote fuel tank to isolate the problem to the motor side but I replaced all the filters and lines back to the fuel tank just to be safe.

I just pulled the plugs a few mins. ago. The plugs were new before yesterday's lake trip. All the plugs look good except the bottom plug on each power head - those plugs are fouled with carbon - burnt looking - they don't look good. Seems like a power head out of tune.

Dunk...do you think could this possibly be a power pack problem sending bad ignition signals.. It looks like the power pack would send bad signals all the time if it were the problem.

[LI Sound Grunt]

If it runs good when the bulb is being primed - its a fuel problem.

[CapnDean]

STOP running this motor until you get it fixed: You seem to have classic case of getting air. Good move checking with a 6 gallon tank. If pumping the bulb keeps you running.....

What is happening is that due to the crack in the fuel line that you cannot/have not found yet... air is getting in. The result is that the furthest and highest distance from the fuel supply.....starves for fuel first. Guess what that means? Your top 2 cylinders will starve for fuel before your bottom two do. Guess what happens when a 2 stroke motor starves for fuel? Yup..it starves for oil too.

[Cummins]

STOP running this motor until you get it fixed: You seem to have classic case of getting air. Good move checking with a 6 gallon tank. If pumping the bulb keeps you running.....

What is happening is that due to the crack in the fuel line that you cannot/have not found yet... air is getting in. The result is that the furthest and highest distance from the fuel supply.....starves for fuel first. Guess what that means? Your top 2 cylinders will starve for fuel before your bottom two do. Guess what happens when a 2 stroke motor starves for fuel? Yup..it starves for oil too

CapnDean...I found a problem - hopefully, THE problem. You're absolutely right about about the top two cylinders being starved for gas, I can see it by the way the plugs look. The top two plugs look a lot newer than the others - the plugs look more used as you go down the powerhheads... Good information..

If it runs good when the bulb is being primed - its a fuel problem.

I did find something. I've always said the same you said here but I never could find anything. Maybe I finally found it......

***********************

As far as not being able to get the motor to prime after sitting a few hrs. or being able to run at troll\ idle speed without it wanting to choke down - you'd have to pump the bulb every few mins. to keep it running:

I replaced the primer bulb\all fuel lines from the tank back to the motor a few weeks ago and oriented the bulb the way I took the old one came off. The primer bulb was installed in the fuel line with the arrow pointing toward the flow of fuel which is correct but the bulb ( arrow ) it's self was pointing down. It should have been pointing up or at the least horizontal. Couldn't get a prime with it pointing down - turn the bulb side ways or up and you get a prime in 3 or 4 squesses. We re-oriented the primer bulb yesterday with arrow up. That might have been the problem all along with not being able to get or keep a prime, especially at low rpm idling\trolling or after sitting a while. It might have been siphoning back out of the fuel line at low rpms due to gravity. I even think the instructions ( instructions are over rated )say to mount the bulb with arrow up if at all possible.

Will take the boat to the lake this weekend to check it out.

Has anyone else had this problem with a primer bulb....arrow down and not able to get and\or hold a prime...?

[fishtexas]

the arrow points to the motor. it shows your fuel flow direction. make sure that you are using a good quality primer bulb. brp 3/8 bulb and not a attwood or tempo. if you can shake it & hear somthing rattle in it toss it.

[Cummins]

Actually your fuel/oil pump system is called an OMS system, not a VRO. Oil Metering System.

" VRO " stands for Variable Ratio Oiling. My original fuel pump had the VRO system from the factory..I've since changed to a non VRO fuel pump. I premix my fuel 50:1 .