No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

[alden135]

If you have read any of my previous posts on this matter please forget them, it's time to start over.<br /><br />J120TLES 1990<br /><br />The following have been replaced:<br /><br />timer base<br />spark plugs<br />power pack<br />coils<br />wires<br />fuel filter<br /><br />This thing will only go 2800-3000 rpm. I removed the plastic carbs today and disassembled them. They are squeaky clean. I did a comp check yesterday #1-125, #2-124, #3-125, #4-125.<br />I made a spark tester and have good spark to all cylinders. I have tested the overheat alarm and it works. I am not getting any alarms after the test beep at start up. My vro seems to be using an appropriate amount of oil. I have moved wires around to see if a spark plug lead was tripping the slow mode. I have a manual and have done the sync/link. I engaged the primer solenoid while at full throttle and it begins to stall. The motor starts/runs great up to the above rpm ceiling.<br /><br />Please help me if you can. Thanks, John

 

[Walker]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

Is you timer base advancing all the way to the stop when you give it the throttle?

 

[alden135]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

Yes it is. The throttle plates are also opening fully.

 

[almost retired again]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

Hello Alden;<br />What kind of plugs are you using? Some plugs can put out an RF interferance that can be picked up by the power pack. I spent at least a half a day one time chasing my tail before I changed out a new set of NGK's and put in a new set of champions.<br />Just a thought

 

[alden135]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

I'm using the champion ql77jc4's that the manual suggests. I wish it were that simple.

 

[MarkHPCA]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

When you say you only get 3000 RPM I assume that is in the water and in gear? If so what prop pitch do you have and has you always used this prop? If it only gets 3000 RPM in neutral then ignore these questions.

 

[alden135]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

It's in the water and in gear. I am over propped right now with the 14X19 prop. I plan on changing that out to a 13 3/4 X 15. I don't think the prop change is going to find my other 3000rpm though. I can only barely get on plane now. I was getting 3500 two weeks ago. I don't have a performance baseline to compare to as this boat is new to me this year and has yet to run "right".

 

[alden135]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

any other ideas?

 

[Walker]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

Could it possibly be that your boat subfloor is water logged?

 

[MarkHPCA]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

What kind of boat is it, length, weight and hull type?

 

[alden135]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

I thoroughly inspected the foam for water when I bought it and it's dry. I have a full camper top which is left on all the time except when I'm using the boat. This is some sort of engine problem.

 

[alden135]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

bump

 

[Dhadley]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

When you say the carb butterflies are full open are you looking at them or at the linkage? You'll have to take the airbox cover off to look at them.<br /><br />DO NOT RUN THE MOTOR UNDER A LOAD WITH THE AIRBOX COVER OFF!!!

 

[alden135]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

Dhadley, I checked them with the air box off. they open with the linkage like they should. I did'nt runn with it off, just to check them.

 

[Salty Tricks]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

Alden<br />I know very little but just went through 6 weeks of aggravation and the same things you did until I found what Dhadley just mentioned. Make sure your carb butterflies are indeed opening when you have full throttle. Your motor need not be running to check this with the airbox removed. Mine was a linkage rod popping off not allowing the lower carb plate to open.

 

[Dhadley]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

OK, we have full advance of everything and good spark at idle. After a run do any of the plugs look any -- any -- different than the others?

 

[alden135]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

I checked all 4 when I did the comp test Sat. They all appear to be a somewhat tan color and a film of oil equal on all. This is begining to drive me nuts, assuming that I'm not already nuts.

 

[Goodoleboy]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

Alden...Are you sure timeing is correct. Use Joe Reeves method.<br /><br />Are you sure that you have no air leaks any where.<br /><br />It sure sounds like one or the other...or both.<br /><br />Even if you are over proped, It should get up above 5000 R's.<br /><br />Good Luck!

 

[alden135]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

My understanding (which could be wrong) is that the wot timing would not make up the minimum 2k rpm I'm lacking before I reprop for the third 1k rpm. I have searched high and low and can't find any leaks. The damn thing runs nice but just won't go above the 2800 or so rpm ceiling.

 

[Goodoleboy]

Re: No guts, need more help with J120 power issues. (* RESULTS UPDATE*)

Alden...Your WOT timeing most certinley will keep you from reaching full RPM,s.<br /><br />If your fireing to late, its not getting anywhere near its full power.<br /><br />If its fireing to early the engine is working aganist its self.<br /><br />Are you useing the Joe Reeves method. Set 4*less than what is called for in manual.<br /><br />Is the timer base free thru its full range. Not sticking before rubber knob hits its stop at WOT.<br /><br />Good luck!