Johnson 115 Wont get above 3000 RPM's without pressing key

[Fj40toycruiser]

I started this thread to begin to diagnose the problem I am having.

http://forums.iboats.com/forum/engi...40764-2004-johnson-compression-test-procedure

I have an 04' Johnson 115 J115PLSRC. I cannot get the boat to go above 3000 RPM's. If I squeeze the bulb no reaction, if I press the key the RPM's climb. It starts fine, idles fine and drives fine at low speed. I have checked the compression...about 120 on all four cylinders +/- 3PSI. The spark jumps 7/16" and is nice and bright blue. I have tried a portable fuel tank no change. I removed the plastic carb bodies cleaned it up and put back together. I did not however touch the aluminum throttle bodies. I am tackling that now. Is there anything in particular to look for and verify is clean in the aluminum housing? jakedaawg has directed me to clean the bodies and believes I am not getting adequate fuel delivery. It looks like the fuel comes into the throttle bodies via a plastic manifold and out through a metal screen that flows into the plastic carb bodies. There is a gasket on the side which I plan to remove and clean real well but I do not see anything else.

 

[interalian]

Pressing the key activates the primer and adds fuel. You're starved for fuel. Might be float levels or blockage in the jets. Time to do full carb rebuilds.

 

[batman99]

With carb covers off and engine running, does one of the carbs spit gas or air flow backwards (out its throat)?

If yes, do investigate its reeds (reed leafs) as well. Especially behind that specific carb.

 

[gm280]

I agree with interalian, when you "press the key" you are enriching the fuel system that is usually used for starting a cold engine. So that points to a fuel delivery issue to me. And that points to the carb(s) as well. I say time to buy some carb kit(s) and clean and install them. It isn't hard to do. I would especially look for trash in the high speed jet circuit because that is where you start having problems. Verify the fuel pump is work properly as well. It can't hurt to check it. JMHO!

 

[jakedaawg]

When you "cleaned" the carbs, did you pay attetiin to the jets? If so that must be done. Simply wiping and spraying out the bowl is not sufficient.

 

[Fj40toycruiser]

Hi guys! Let the laughs begin. When I was out on the water at WOT and not getting above 3 grand I took the cover and silencer off to observe the carburetors. I then had a driver drive while I placed my hand in front of each carburetor. Each carb seamed to respond the same way until I reach the 4th one..... When my hand was placed over that carb the RPM's increased and the boat speed went up. So I swamped said carb to another location and it repeated the increase in rpm's. So I took the carb apart to see what was going on, everything looked good till reassembly.....I went to reassemble and observed the round nickel sized gasket in the center between the carb and the bowl of the carb was missing. Installed the gasket as designed took it to the local pond and sure enough 5000 RPM's at about 43MPH with 3 people in the boat everything seems good to me..whoohoo!. Now on to replacing the flush mount remote shift cable as the anchoring point broke and no longer shifted correctly during trouble shooting. Any pointers for this process? Or am I in the wrong forum?

 

[gm280]

Hi guys! Let the laughs begin. When I was out on the water at WOT and not getting above 3 grand I took the cover and silencer off to observe the carburetors. I then had a driver drive while I placed my hand in front of each carburetor. Each carb seamed to respond the same way until I reach the 4th one..... When my hand was placed over that carb the RPM's increased and the boat speed went up. So I swamped said carb to another location and it repeated the increase in rpm's. So I took the carb apart to see what was going on, everything looked good till reassembly.....I went to reassemble and observed the round nickel sized gasket in the center between the carb and the bowl of the carb was missing. Installed the gasket as designed took it to the local pond and sure enough 5000 RPM's at about 43MPH with 3 people in the boat everything seems good to me..whoohoo!. Now on to replacing the flush mount remote shift cable as the anchoring point broke and no longer shifted correctly during trouble shooting. Any pointers for this process? Or am I in the wrong forum?

It is always great new when you figure out what is wrong. Bravo sir Bravo. :thumb:

 

[GA_Boater]

Hi guys! Let the laughs begin. When I was out on the water at WOT and not getting above 3 grand I took the cover and silencer off to observe the carburetors. I then had a driver drive while I placed my hand in front of each carburetor. Each carb seamed to respond the same way until I reach the 4th one..... When my hand was placed over that carb the RPM's increased and the boat speed went up. So I swamped said carb to another location and it repeated the increase in rpm's. So I took the carb apart to see what was going on, everything looked good till reassembly.....I went to reassemble and observed the round nickel sized gasket in the center between the carb and the bowl of the carb was missing. Installed the gasket as designed took it to the local pond and sure enough 5000 RPM's at about 43MPH with 3 people in the boat everything seems good to me..whoohoo!. Now on to replacing the flush mount remote shift cable as the anchoring point broke and no longer shifted correctly during trouble shooting. Any pointers for this process? Or am I in the wrong forum?

Since this about carb issues, remote control questions may be overlooked. It is better to start another thread in Steering & Controls.