79 115hp wont open up

[jda913]

i got a 79 115hp evinrude that was running a lil rough cause of some bad gas but it was running around 45-47mph with no problem....well i took the boat to a local boat shop to have the carbs cleaned and when i get it back itsonly running 35mph now but still real strong...i took it back to the shop and after about 2 hours of troubleshooting he tells me the hub is spun in the prop, so i get the prop fixed and still the same problem...it sounds like it wants to go but just wont open up all the way, i took it back to the mechanic and he went through it again and made sure the butterfly valves were all the way open and they were, then he looks at me and shrugs his shoulders and says "well i dont know what to tell you"...this was after i spent $300 with him....can someone tell me something please

 

[Joe Reeves]

Re: 79 115hp wont open up

A mechanic worked on your engine and now the rig travels 10 to 12 mph slower. Apparently you need to do some trouble shooting on your own.

Check the compression which should be approximately 100+ psi and even on all cylinders. What readings do you have?

What spark plugs are you using? They should be Champion QL77JC4 plugs gapped at either .040 or .030 (try both gaps).

With s/plugs removed, rig a spark tester whereas you can set a 7/16" gap. The spark should jump this gap with a strong blue lightning like flame... a real SNAP! Does it?

The small orange wires leading from the powerpack to the coils... the orange wire with a blue stripe must always be connected to the top cylinder coil.

Let us know what you find.

 

[DargelJohn]

Re: 79 115hp wont open up

The mechanic worked on the carbs, I would take a close look at the throttle linkage, especially the spark advance.

 

[boobie]

Re: 79 115hp wont open up

Make sure your time base is free and working through it's full range of travel.

 

[jda913]

Re: 79 115hp wont open up

Compression was 125 all the way across....sparks plugs are new, not sure the brand though...i did the spark test and its doing the spark...the only thing i havnt checked is that wire your talking about, ill check that in a few minustes....thanks alot for your advice....

A mechanic worked on your engine and now the rig travels 10 to 12 mph slower. Apparently you need to do some trouble shooting on your own.

Check the compression which should be approximately 100+ psi and even on all cylinders. What readings do you have?

What spark plugs are you using? They should be Champion QL77JC4 plugs gapped at either .040 or .030 (try both gaps).

With s/plugs removed, rig a spark tester whereas you can set a 7/16" gap. The spark should jump this gap with a strong blue lightning like flame... a real SNAP! Does it?

The small orange wires leading from the powerpack to the coils... the orange wire with a blue stripe must always be connected to the top cylinder coil.

Let us know what you find.