Johnson 25hp no Mid-range or Wide open throttle

[kskomro]

No Midrange or Wide Open Throttle. 1988 Johnson 25HP, Starts fine, runs good at low speed. When I open it up it only gets to about 6 MPH. I rebuild carb yesterday, sprayed through all the ports, replaced valves, gaskets and still have the same problem. I can see the butterfly inside wide open. I've disconnected the linkage and manually gave it throttle and still no wide open throttle. I don't really think there is any midrange either. I did have a marina tune it up this winter.

 

[F_R]

Re: Johnson 25hp no Mid-range or Wide open throttle

It probably is running on one cylinder. Disconnect and ground one spark plug wire and run it. Then repeat with the other wire. Chances are it won't even run when you disconnect the good one. Then zero in on the bad one to see what's wrong with it. You did try a set of new plugs, didn't you??

 

[kskomro]

Re: Johnson 25hp no Mid-range or Wide open throttle

It probably is running on one cylinder. Disconnect and ground one spark plug wire and run it. Then repeat with the other wire. Chances are it won't even run when you disconnect the good one. Then zero in on the bad one to see what's wrong with it. You did try a set of new plugs, didn't you??

I just had it tuned up with new plugs butttt, you make alot of sense. My first time out with it, the motor took off like a raped ape, then about 500 yards out it dropped off. My question is would it start and sound good at low speed.

 

[tashasdaddy]

Re: Johnson 25hp no Mid-range or Wide open throttle

they will run at low speeds on one.

 

[kskomro]

Re: Johnson 25hp no Mid-range or Wide open throttle

Thanks. That I will try. This boat has been the nightmare from He%%

 

[HighTrim]

Re: Johnson 25hp no Mid-range or Wide open throttle

What parts were replaced during the tune up?

Either a faulty power pack or ignition coil will USUALLY cause this problem. Some more rare causes would be a weak trigger magnet in the flywheel or a faulty timer base.

IF you find a faulty cylinder, start by swapping the coils, if the problem follows the coil, replace it. If the coils are fine, it is likely the PP. This will need to be tested as per your manual. Do you have a DVA meter?

 

[kskomro]

Re: Johnson 25hp no Mid-range or Wide open throttle

What parts were replaced during the tune up?

Either a faulty power pack or ignition coil will USUALLY cause this problem. Some more rare causes would be a weak trigger magnet in the flywheel or a faulty timer base.

IF you find a faulty cylinder, start by swapping the coils, if the problem follows the coil, replace it. If the coils are fine, it is likely the PP. This will need to be tested as per your manual. Do you have a DVA meter?

DVA Meter? I have all types of multi meters, but not sure what a DVA Meter is.
I just ran out and did a visual on the plugs. One plug is normal, the other is oil soaked.
Previous to this problem I had concern of the water pump, so the motor was run for awhile at low RPM's but not overheated. could this have loaded up and fouled the new plug? During the tune up, the flywheel was pulled and something he said was scraping the flywheel he tightend it, told me it would be fine.

 

[HighTrim]

Re: Johnson 25hp no Mid-range or Wide open throttle

DVA meters are specialty meters for measuring average DC voltages and AC voltage spikes on ignition systems. Necessary for much of the testing without an old neon tester.

Having a wet and carboned plug could mean your mix is too rich, too-cold a plug, a bad fuel-oil mixture, bad oil, worn rings, or a bad ground on ignition.

I have a feeling you should bring it back, one of my aforementioned 'rare cases', may in fact not be so rare.

 

[F_R]

Re: Johnson 25hp no Mid-range or Wide open throttle

Numerous things can cause it to run on one cylinder. I told you how to determine which one it is. After that, a compression check is in order to make sure you don't have internal engine problems. If that is OK, then check for spark. It should jump a 7/16" gap. Checking for jumping the plug gap outside the cylinder is not a spark test. A ruptured fuel pump diaphragm can flood the cylinder that provides the pulse to the pump.

 

[kskomro]

Re: UPDATE

Re: UPDATE

Mechanic just called, he found the power packs are N/G. He said hopefully that is it. He had to order them. He told me I should here back tommorow.

 

[locked and loaded]

Re: Johnson 25hp no Mid-range or Wide open throttle

Hey i have a 75 model johnson 25hp and it is doing the same thing.Put new plugs rebuilt card checked fuel sys. and just put the plugs against head to see if there was spark ect still fooled about it. Runs like a champ idle low end just at full turn on tiller feels like it is not hitting high rpms. WHAT am i doing wrong about to git rid of for another if i cant get running right but dont want to please any help would be great

 

[kskomro]

Re: Johnson 25hp no Mid-range or Wide open throttle

You should check or have checked your power pack. even if it faulty, it will idle great, rev up even, but full throttle you won't even get 10 mph out of it. Also your carb my need cleaning or rebuilding. I rebuilt mine, it was not that hard.

 

[Skifferskipper]

Re: Johnson 25hp no Mid-range or Wide open throttle

I Have a 74 and Im having the same problem.. A Guy told me to check the stator and make sure the diods were not damaged.. Problem is I Dont know any tests for this? is there any truth to this?

 

[hidef]

Re: Johnson 25hp no Mid-range or Wide open throttle

Can you please open a new thread this one is over 3 years old.

 

[mikeshoebuilder]

Re: Johnson 25hp no Mid-range or Wide open throttle

I have a 93 25 hp Johnson that I have never had any problem with but it started doing something similar it runs great at low rpm but when you throttle up it starts pulsating anyone have any ideas on what could be causing that??

 

[Daviet]

Re: Johnson 25hp no Mid-range or Wide open throttle

Please start a new post, this one is over 3 years old.

 

[larryg]

Re: Johnson 25hp no Mid-range or Wide open throttle

guess they didnt see ur first post.lol i have the answers ,hopefully,for you guys if you start a new thread.

 

[cfoodluva]

Re: Johnson 25hp no Mid-range or Wide open throttle

motor runs great without cover on, and when cover is put on theres no power at full throttle need help.

 

[AlTn]

Re: Johnson 25hp no Mid-range or Wide open throttle

click on the blue box above the forums..it says, "Post New Thread"...year, hp, and model no. help when asking a new question

 

[cfoodluva]

Re: Johnson 25hp no Mid-range or Wide open throttle

i have a 1968 20hp johnson model# fd-22E. motor runs great without cover , but when the cover is put on , theres no power at mid-range or full power need help please.