1986 gt 200 johnson problems

[dhouser]

My motor on my bass boat has no low end power and will barely get on plane if at all. It seems like its running rich it idles perfect and when at wide open throttle it runs great but runs poor at low speeds and has no power. ive replaced spark plugs tore apart all 6 carbs and cleaned them repaced fuel hoses that were cracked. Anybody have any idea or exerience with this motor or have seen this problem before.

 

[dehydrated]

Re: 1986 gt 200 johnson problems

do you know what idle jets and mid jets your running might be your problem

 

[clanton]

Re: 1986 gt 200 johnson problems

How much throttle do you give it, when getting up on plane? How many rpms full throttle on plane?

 

[dhouser]

Re: 1986 gt 200 johnson problems

the jets are 14s and 16s not sure wich is wich though. It will run 5200rpms at wot once it gets there. It runs fine in the tank with a test prop it will run 5800 rpms in the tank and with the reg prop it runs 3k -3500 in the tank.

to try and get it on plane ive tried a little throttle haf throttle and full throttle

 

[clanton]

Re: 1986 gt 200 johnson problems

You have a real test prop? You need a DVA meter or adapter, with long leads. Connect meter to primary side of ignition coil. Engine at operation temp, full throttle bringing boat up on plane. Have your helper watch meter and take readings. check all 6 coils, reading must be same all 6. I don`t have spec handy, over 100 volts. You have one or more cylinders low voltage, Then move to stator test. Have you looked at the flywheel magnets, coils, sparkplugs, and sparkplug wires.

 

[clanton]

Re: 1986 gt 200 johnson problems

5200 a little low, but may inprove after you find the problem.

 

[dhouser]

Re: 1986 gt 200 johnson problems

Yes its a real test prop my buddy is good friends with the owners of a boat shop. so they let us use there tank and tools if needed. We checked to make sure all 6 were firing under a load in the tank with a timing light all were firing. Havent checked anythbing else. spark plugs are new plug wires looked good none arcing on the block etc. coils look good not sure how to test anything else or what to look for as ar as magnets go.

 

[dhouser]

Re: 1986 gt 200 johnson problems

the prop that is on there is a 3blade 26 pitch.

 

[clanton]

Re: 1986 gt 200 johnson problems

The magnets get loose under the flywheel, should be able to see this without removing the flywheel. I would still check the voltage with the meter, and timing at full throttle 5000 rpms. I think you have too much prop. Engine sound like it is misfiring?

 

[dhouser]

Re: 1986 gt 200 johnson problems

Ill check the magnets tom mornin. so if i check the voltage and there low or diff what des that mean? and what will that cause? it runs perfect at higher rpms then if ya slow down or try to get up it sounds like it misses. I have a 21p prop that im gonna try as well.

 

[clanton]

Re: 1986 gt 200 johnson problems

Low voltage= misfire. Check the voltage when it sound like its missing. The engine and ignition system is loaded the most comming up on plane. The presser is the highest in the cylinder at this point and takes more voltage to fire the cylinder. If the voltage is low or erratic, then you move to stator test. Stator has 2 sides, 1 for port bank, one for starboard side. 2 sets of brown wires from under flywheel. check at cranking rpms, I will get manual tomorrow for specs. Flywheel, powerpack, stator, and timer have high failure rate.

 

[dhouser]

Re: 1986 gt 200 johnson problems

That sounds good. ill look for ur post tom. and check the voltage

 

[clanton]

Re: 1986 gt 200 johnson problems

175 volts at the primary side of the coil. 200 volts at the charge coil .