Power pack issue

[misfit171]

Would I get spark if my power pack was going out ? Cause the symptoms seem to point to back power pack but I have lots of spark?

[phillnjack]

you need to put a bit more detail as to what is happening exactly.

are you getting the correct amount of spark i.e is the spark jumping atleast 7/16 of and inch ?
is it bright blue ?
have you checked its firing at the right time ?

what engine model and year





phill

[misfit171]

It's a 78 115 evinrude . It gets up to high rpms or WOT then bogs down then runs back up in rpms then bogs ? till it quits. It will run at mid rpms but still feels like there is a hesitation. I have good compression and the spark is very blue but have no spark tester at the moment. Before it would run good in the driveway but now just starts fine and sounds like its gonna be ok then revs down and sounds funny like it missing. I've rebuilt the carbs the fuel pump and cleaned and changed out my gas tank and water seperator. Has a new prop and lower unit oil. I misted it with water to see if there was any shorts. There was none. I'm taking it to a friends this week to try to sync the carbs he thinks that is the problem???????

[phillnjack]

what the hell are you doing misting it with water ?
whoever has told you to do that is crazy.

now when you say high revs at wot, what revs are you getting.
what you say is high might be well under what it should be.

what prop are you using ? size and type etc.
what is the idle revs ?

you need to be a lot more precise with the facts to get this engine running right.
ive known people have an engine 10 years thinking its developing full power and running right etc, then when shown what it can really do they are amazed.

you need to be getting 5500 rpm minimum to get the hp of the engine.
the idle needs to be around 900 if out the water on muffs and around 750 to 800 in the water.

cleaning out carbs is often done without leaving the carbs soak in carb cleaner, and rebuilding the carbs means completely taking out everything including the freeze plugs.

Have you checked the floats for the correct level ?
did you put on new carb gaskets ?
have you checked for any air leaks ?
have you done a fuel pressure test ?
is the timing correct at isle and at fully advanced ?

you need to know what compression it is in psi, what are your reading of all cylinders ? are they within 8% from lowest to highest ?
have you done a decarb recently ?
is the fuel very fresh and at correct oil ratio ?
you need to check the stator is clean and that all magnets are still in place correctly.

how brittle are the coil wires and is there ANY small cracks around the coils ?

best time to look for shorts is at night when its real dark, youl see any slight spark that you would miss during daylight.

and do not ever spray any water over the powerhead at all.
it will not show up a short,but could destroy the electrics and then the motor would not be worth spending on.

what size is the new prop and what boat is this on ?

although it sounds like a fuel problem, I would be looking for a bad coil.
these older motors need good coils, and if these are original they will probably be bad by now.





phill

[misfit171]

It's on a 24 foot 89 Lowe pontoon boat . Don't have a way of knowing rpms no tach. I have 125 psi on all cylinders but one that is 130. When I say high rev I mean WOT. I have a 4 blade Michigan prop 13 3/4 with a 13 pitch. I soaked the carbs in sea foam deep creep and yes changed the freeze plugs and all new gaskets . Didn't really mess with the floats. Don't know what a decarb is? Gas is fresh with 50.1 oil and the tank is new and clean as a whistle. If it was the coil would i get spark at all on that cylinder. Got another one for ya I was going to pull the spark plug boot off to see if it bogged a little at idle and even with rubber handled pliers and a leather glove it lit me up. When it did I pulled the boot off . Crammed it back on cause it didn't look like it broke may have just been sitting in there ? Anyhow it fired right up and sounded a hair better?? I'm taking it to a mechanic friend Saturday so I will hopefully get enlightened on more of the issues. Thanks for your time I know I sound like an idiot on here but it's really hard to explain this stuff.

[phillnjack]

You don't sound like an idiot at all.
I know only too well how hard it is to get across sometimes exactly what is happening.

recently on another forum it took me 3 days to explain what was happening to my engine, everyone thought I meant something totally different ha ha .

coils can give great spark sometimes when plugs are out, that's why its best to use a spark air gap tester, it lets you know the spark will actually jump 7/16ths.
coils also often break up under load once they warm up a touch.
it can be very frustrating with electrics due to not being able to actually see whats going on.
I prefer a mechanical problem, its easy to see something broke



phill