not getting up to full speed

[bigd5977]

Re: not getting up to full speed

No,, i don't need a spark tester,, i'm getting a blue spark from it, & i did another test too that i used to do on older car & truck engines,, while running at idle at home with water going to the shaft , i pulled 1 plug wire off at a time, the engine did seem to go down,, but it almost sounded like it was smoother idle then when all 3 are connected & yes i did do this on all 3 plugs,,, I'M REALLY CONFUSED NOW

 

[eavega]

Re: not getting up to full speed

Fireman
Does he need a timing light or just a simple spark tester?

Spark tester is the wrong tool to verify spark under load. An inductive timing light will verify the electrical pulse from the coil to the spark plug while not interfering with the actual function of the spark plug on a running engine. It tends to be a little scary to hover over a spinning flywheel while bouncing along at WOT, so do it on a quiet day on the water, preferably in the twilight hours so you can more clearly see the light pulse from the timing light.
Also, I have found timing lights at Harbor Freight, Pep Boys, Northern Tools, and actually purchased one on Amazon.

Rgds

 

[bigd5977]

Re: not getting up to full speed

ok i did another test on spark , by pulling the wires like i said earlier & found that the top cylinder dies down real low & the other 2 cylinders go down a bit but nothing like the 1st one,, top 1,, also found a fuel leak now on the fuel pump gasket , so i need to get a gasket for that,, & yes its on the gasket, not the fuel pump diaphragm,, so any ideas on the 1 cylinder dieing down so much ???

 

[fireman57]

Re: not getting up to full speed

It could be the coil getting weak when hot. That is why, if you can, you test it with a timing light when it is acting up. Yo might do a compression test. The numbers need to be within 10% of each other. Might be getting water in the top. I hope not.

 

[bigd5977]

Re: not getting up to full speed

ok getting ready to do Compression test,, finally got compression tester & timing light,, now how could i be getting water in the top & where?? no water goes up into the motor on a 2cycle does it ??? its just in the prop shaft i thought,, maybe i'm wrong ????

 

[kfa4303]

Re: not getting up to full speed

Actually, water does circulate around the motor. Water is drawn in the leg and accelerated up a copper tube(s) by your impeller(waterpump). The water then cycles around the cylinders through channels in the engine block and draws off heat before it is "spit" out the back along with the exhaust and/or telltale. If you are getting water in the cylinders, the most obvious explanation would probably be a blown head gasket, but it could several other things as well. You definitely don't want water around your propshaft. That should be sealed in the gearcase with 90w oil.

 

[bigd5977]

Re: not getting up to full speed

ok i did a compression test on it & it was 120, 115, & 115,, now i can't get it started again because i think the fuel pump went,,, Will the fuel pump go just like that?? getting gas to the pump but not to the carbs all of a sudden,,, need more help PLEASE,, & there is no water in the cylinder just wet from gas & fume

 

[watergecko]

Re: not getting up to full speed

Disconnect the fuel hose going from pump to carbs, there willbe an arrow on the pump pointing down to hose, thats ur outlet. Disconnect there, crank motor quickly and see if fuel pulses out, if not ur pump is shot. Prob 100 new from dealer, easy fix. There is a chance though there could be obstruction in lines or tank depriving pump of fuel. So pump bulb with fitting off fuel hose, that will verify fuel tomotor.

 

[bigd5977]

Re: not getting up to full speed

ok , the fuel pump is working again now,, my compression is 120, 115, 115, now i have to get some good water pressure going or put the boat in the lake to do the timing test with the timing test,, can i do it with just a water hose connected to it with a earmuff on ??? or can i put it in a 55 gal. drum full of water ?? or should i be out on the lake,, kinda dangerous on the lake i would think ?????

 

[fireman57]

Re: not getting up to full speed

No you can't do it with muffs. You have to be on the water to create the conditions in which it is acting up. You said it does it at wot. When it does it check it with the timing light. Your compression is good. It's not that dangerous because when it does it you slow way down. At that point have your buddy put the wire from the timing light on a spark plug wire and see what happens on each wire.

 

[bigd5977]

Re: not getting up to full speed

ok i finally did the compression check & it's 120,115,120 ,, & the timing light test was flashing on all 3 cylinders, but still can't get full throttle, it runs the same at full as it does at 3/4 throttle,, you can hear that it wants to go but wont,,, anymore ideas,, fuel mix is 50:1 & how do you bring down the idle on it,, sounds like it idles very high to me,, NO i dont have a RPM gauge on it

 

[AlTn]

Re: not getting up to full speed

take a spray bottle with fuel mix in it and at this "3/4 won't go any faster point"...spray fuel mix in the carb throats, if it picks up rpms..you have a fuel delivery issue, if the motor bogs..it's getting enough fuel and it's time to check the ignition system...you are at a point that it would really benefit you to get an OMC factory manual and follow the link % sync procedure outlined in it

 

[bigd5977]

Re: not getting up to full speed

ok, the timing light is working on all cylinders when i'm trying to hit WOT,, but motor is still hitting at 3/4 throttle & it doesn't make a difference with a spray bottle,, it still acts & sounds the same,, checked the bowl on all 3 carbs & getting between 1/8-1/4 cup of fuel out of each,, jets are clear & clean

 

[1969johnson55]

Re: not getting up to full speed

Spark tester is the wrong tool to verify spark under load. An inductive timing light will verify the electrical pulse from the coil to the spark plug while not interfering with the actual function of the spark plug on a running engine.

Rgds

ok i have a simple spark tester looks like a pen with curver spot on one end just touch it to wire and it flashes works without interfering with ignition i beleve that is what he was talking about not one that atached to end.

 

[bigd5977]

Re: not getting up to full speed

ok,, all testing done with timing light, compression tester & everything is good to go ( ON THE TEST ),, but still takes a bit to get warmed i guess or for the motor to get the boat moving,, i am told now that if i can squeeze the fuel bulb while its running & the bulb is not firm already & i go back again to squeeze it when its acting up & i can squeeze it again to get firm,, it means the FUEL PUMP is not working right & needs to be REBUILT or new pump put on,,, so next question is,, what is the difference between a 75ELR77S fuel pump & a 75ELR77 pump ????? please help,, TY

 

[Daviet]

Re: not getting up to full speed

When I use your model number 75ELR77, it automatically changes to a 75ELR77S. below is a picture of a 75ELR77S, does it look like yours?
http://www.marineengine.com/parts/j...ELR77S&manufacturer=Johnson&section=Fuel+Pump

 

[bigd5977]

Re: not getting up to full speed

YES,, that is what i have

 

[Jim311]

Re: not getting up to full speed

Maybe your fuel line is bad or has a small leak? It is able to get enough fuel until it gets to 3/4 or wide open throttle, at which point it starts sucking air and is starved for fuel. Just a guess.

 

[bigd5977]

Re: not getting up to full speed

it does get up to full throttle sometimes,, but takes forever to get it there,, some days it does it & other days it wont,, most of the time it wont

 

[Daviet]

Re: not getting up to full speed

I just scanned tjrough all the posts here and have a few thoughts.
All it takes to make your engine run properly is compression, timed spark and fuel delivery, that's it.
Compression, it sounds like you covered that and it is OK.
Timed spark, again, it sounds like the engine starts and runs, just no top end, should be OK there.
Fuel delivery, sounds like your fuel pump is not the problem, no difference when squeezing the primer bulb. Have you overhauled the carbs, pulled the high speed orifices and made sure they were not plugged or restricted? Float levels at proper settings? Carb base gaskets in good shape? Are all the throttle plates open the same amount at WOT, should be 90% to the carb bore.
Like I said in the beginning, these are just some thoughts.