runs bad back down to idle

ldixon

Cadet
Joined
Nov 27, 2009
Messages
17
1989 Johnson 28hp SPL Outboard

Lately i have had some trouble with this motor, I finally have it running past 1/2 throttle. Before it would just jump really bad and not gain any rpms.

Today i ran some tests in a test tank before re-checking the timing. i retarded it 4 degrees at wot because i did not have it hooked up to water or in a tank.

I rev it up and it does good it gets to full throttle, but when i let off it jumps really bad on the way back down to idle.

Any tips?
 

kenmyfam

Supreme Mariner
Joined
Aug 10, 2006
Messages
14,392
Re: runs bad back down to idle

How about the basic health check ???
Compression
Spark
Fuel delivery
Spark plug condition.
 

ldixon

Cadet
Joined
Nov 27, 2009
Messages
17
Re: runs bad back down to idle

compression : 110ish and 100ish
Spark is good: New CDI Powerpack Stock coils but seem ok
Fuel is Good: Carb was Rebuilt 1 week ago, bulb stays firm, did not do a reading on fuel pressure but seems strong.

As i said, I have not fine tuned the timing. Also, is it okay to run the motor at wide open trottle in a 55 gallon steel drum? I would think so but do not know for sure.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: runs bad back down to idle

NEVER, NEVER "i did not have it hooked up to water or in a tank. " you have probably toasted your impeller. no you cannot rev over 1500 rpms in barrel or on muffs. did you remove and clean the jets in the carb rebuild, use a new kit??? once the fuel pump picks up fuel the buld in not suppose to be hard.
 

bktheking

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Joined
Jul 29, 2008
Messages
5,057
Re: runs bad back down to idle

NEVER, NEVER "i did not have it hooked up to water or in a tank. " you have probably toasted your impeller. no you cannot rev over 1500 rpms in barrel or on muffs. did you remove and clean the jets in the carb rebuild, use a new kit??? once the fuel pump picks up fuel the buld in not suppose to be hard.

Ya uh I missed that one reading this post, ran WOT/no water, I hope he mistyped something there and means set without it running!!!!:eek:
 

kenmyfam

Supreme Mariner
Joined
Aug 10, 2006
Messages
14,392
Re: runs bad back down to idle

I missed the no water thing as well !!!
Time for a water pump service !!!
 

ldixon

Cadet
Joined
Nov 27, 2009
Messages
17
Re: runs bad back down to idle

Lol, yea that would be bad, very bad. i had a bad water pump impeller to start with. so i purchased a new kit, housing and everything. but befor i put it in i pulled both plugs hooked up spark tester to 7/8s". set to wide open throttle, had buddy turn over motor with fuel unhooked. i then set the timing to 26 degrees. i read in a form that it would add 4 degrees when actually running at wot. so anyways after i did this i installed new pump and droped it in a barrel. now.. can i not rev to wot in barrell?
 

ldixon

Cadet
Joined
Nov 27, 2009
Messages
17
Re: runs bad back down to idle

NEVER, NEVER "i did not have it hooked up to water or in a tank. " you have probably toasted your impeller. no you cannot rev over 1500 rpms in barrel or on muffs. did you remove and clean the jets in the carb rebuild, use a new kit??? once the fuel pump picks up fuel the buld in not suppose to be hard.

what should i do? would it be best to back trailer down landing on the river and set it there? or do i actully need it running down/up the river... i dont want to hang off the back of the boat.lol

i dont know, yall tell me...
 

bktheking

Vice Admiral
Joined
Jul 29, 2008
Messages
5,057
Re: runs bad back down to idle

now.. can i not rev to wot in barrell?

Nope, like Tashasdaddy said, 1500rpm or less. You will have do this in the lake my friend, not enough back pressure in a barrel, you run the risk of run away or better yet, kaboooooom and we don't want ya blowing that nice motor up.
 
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