still no wot rpms

[splitshot]

well i got the motor back together friday night and broke it in saturday...1977 140 johnson on a 1985 hydrasport bass boat..i went ahead and went through the carbs while i was rebuilding they were clean as were the orfices...and i still can only get about 3200 rpms out of it...

checked compression all cylinders are exactly 130 psi...cheked timing 3 degrees base timing i guess you would call it (no advance) then i had 28 degrees advanced....put new plugs in it i pulled them after break in and they were black and a little wet...not dripping but kinda moist

i havent had time to see how far the spark would jump...my book says 1/2" but all i have seen on here is 7/16" which is it ?? i am guessing the problem is going to be ignition related... when i have it at 2000 rpm about every 5-6 seconds it will miss....but any higher or lower it does not miss at all...i will test the spark tomorrow...

i even checked the butterflies in the carbs at full throttle they are wide open and timing is against the rubber stop just like it should be...also the reeds were good when i rebuilt

also going to pull my tach and make sure it is connected right..although the boat at 3200 rpms does about 37 mph so i think its about right....

any help is greatly appreciated on any ideas !!!

 

[splitshot]

Re: still no wot rpms

ok did the spark test..the spark will jump a 3/8 gap on all cylinders if it put it on a 7/16" gap i would fire few and far between...so i put it on muffs and let it idle i pulled each plug wire and one by one they lowered the rpms...so what do i need to test now ??

also when i was running it on the water the other day after break in..i pushed it to full throttle just long enough to push the choke in and it choked the motor so i dont think there is a fuel problem right ??

 

[Benny1963]

Re: still no wot rpms

hook up a timeing light to each plug and watch the light ,
bring rpm up to problem rpm and watch light with motor running on each cyl to see if it is breaking down at that rpm you will be able to see it in the light

 

[splitshot]

Re: still no wot rpms

can i do this in neutral ?? i dont have anybody to ride and check while i drive...or is there another way

 

[Benny1963]

Re: still no wot rpms

yes i guess you could but i would do it under load.
strap it to the trailer well put some one in truck to mash breaks
run it up to were your prob lies and see if you have erratic spark
on all cyls . you could also check were your timeing is at
your max rpm and make sure your timer base has hit stop
when you check timeing

 

[kyrock]

Re: still no wot rpms

Might sound a little obvious, but I was having the exact same issue with my '82 Johnson 90. I went through every listed test in the Seloc. It turned out that I had a fuel line dry rotted the one that goes from the ?t? between the carbs and runs to the primer solenoid. Replaced the line and she ran like a top. Hope it helps!

 

[splitshot]

Re: still no wot rpms

well i appreciate the help but i already replaced the fuel line when i rebuilt the carbs it was old too but didnt help...only thing not replaced or rebuilt is power pack, coils, stator and timer base...thanks

 

[quackaddict1]

Re: still no wot rpms

37 mph tells me the motor is pushing decent power, can you verify the tach is right?

 

[splitshot]

Re: still no wot rpms

it is hooked up right but i dont know how to check the actual reading without getting another tach and hooking it up...

 

[quackaddict1]

Re: still no wot rpms

does the motor sound like its winding out? Is the prop wrong way to big for the motor?

 

[splitshot]

Re: still no wot rpms

i'm going to have to get something to test the tach because to me it sounds like its not wide open but i dont know...its hard to tell...when its idling the tach is around 700 rpms if it was off wouldnt that number be off too ?? i have had this problem with this motor since i got the boat and to me the boat should go faster than 37mph...not trying to win a race but it is a fairly light boat (16ft hydra sport) the prop is a 13-1/4 X 17...would an automotive style dwell meter work ??

 

[quackaddict1]

Re: still no wot rpms

Sounds like the tach is working right if it reads at the low end. 700rpm is close. I don't quite know what to think of this...

 

[splitshot]

Re: still no wot rpms

maybe the power pack ?? nothing melted on the stator...timming base moves good and when i tested spark to me it was weak..it would jump a 3/8 gap but not anymore than that and it was on all cylinders....unless i have 4 bad coils which i'm guessing is a very long shot

 

[splitshot]

Re: still no wot rpms

....

 

[splitshot]

Re: still no wot rpms

Did an ohms tes on the timer base and the reading was 11.5 acceptable is 10-20...does this mean it is going bad since it isnt closer to 10 or 20 ?? i also did an ohm test from the ground on each coil to the hot lead on the power pack (to each coil) and i got .4 ohms does this mean the coils are good too ?? i'm trying to figure this out w/o buying the expensive testers...i have enough spare $$$ to buy either the power pack or the coils right now but i cant see the 4 coils being bad....

 

[Benny1963]

Re: still no wot rpms

doubt its in your coils have you tried the timeing light on the muffs at the rpm its shutting down see if ya have a cyl breaking down do you have bright blue spark when you test it for spark on all cyl may be pack if ya have a coil bresking down it would probaly not fire a cyal then you could swap with cyl that is fireing and see if prob follows if it has blue spark on all when tested
you need to use timeing light on each cyl look at it when you get close to the point it stops revving look at the light to see if its flashing consistant
then move on to another till ya find out what cyl is breaking down
may have to do it in water if ya have to pull it to 3000
since you really dont want to wind it up high without bcakpressure
cdi has a troublr shooting pdf files for evin electrinic
you can test everything with dva meter but you said you were working with basics like me ,so i use timeing light to find spark issus under load
good luck you will get it

 

[splitshot]

Re: still no wot rpms

ok just got back from the river boat still dripping ...first thing i did was test the timming again it was 3* at idle and 18* at 3000 rpms....i tested each plug wire where i had the miss (2000 rpms) with the timming light they all flashed the same no sign of a miss at all even though it was missing about every 10-15 seconds....then i got it going wide open (3000 rpms) and went from plug wire to plug wire and they all flashed the same (very very fast pretty much a fluttering)....when should the timming be fully advanced to 28* at 5500 ?? what does all this tell me and whats the next test thanks for being so patient and working with me on this problem....

 

[Benny1963]

Re: still no wot rpms

no ibelieve your timer base will stop it before your carbs open all athe way
upp may try going back thru you throttle pickup point timeing
are you butterfly all the way open at 3000rpm if so you need more help than ican give provided your tach is right and your butterflys are opening all the way you should have wot timeing at 5000 not 18 if your boat would pull to 5000 your timeing should be what is recomended im lost hopefully one of the gurus will jump in so its top rpm is 3000 and all the cylhave you s are kikkin and you went thru carbs yes 28 at 5500 or 5800
will be thinking about it

 

[splitshot]

Re: still no wot rpms

anybody can we rule out the coils and power pack ?? or is power pack still a possibility ??

 

[splitshot]

Re: still no wot rpms

???