Jono 55 idle / acceleration problem

[wojtech]

Hey All, Got this problem with my 55 Johnson. Idle is a little uneven and sometimes it stalls (which is no good when trolling near coral!!), when I gun it lags and almost stalls but slowly winding on the throttle it eventually starts to run great with no misses and has full power. I suspect fuel pressure problem and am going through the fuel system now, am I wasting my time??

 

[JB]

Re: Jono 55 idle / acceleration problem

Model number??

 

[ENSIGN]

Re: Jono 55 idle / acceleration problem

Have you checked the gas?

 

[tashasdaddy]

Re: Jono 55 idle / acceleration problem

what have you checked? compression, spark on all cylinders? year or model # of motor, so we know what you have.
welcome to iboats.

 

[wojtech]

Re: Jono 55 idle / acceleration problem

Hey guys, Model is Johnson AJ55RSLP, Yes have checked compression (exactly 130 psi in both) have recently changed both crankcase seals. When tested at home I get a good fat spark in both plugs. Fuel is brand new 98 ULP @ 50:1 mix. Don't have any starting problems and like I said once I get it going it runs properly with heaps of power. Just has the uneven idle (it surges from running smooth to running bad) and when I gun it it kinda feels like an old carby'd car with accelerator pump issue.
Had a look at fuel pump yesterday, diaphragm didn't look too good so have replaced also replaced filter and feed lines.
Will do a water test today and hopefully that fuel pump was it.

Will let you know how it goes. Maybe get a couple of barramundi out there fingers crossed.

 

[tashasdaddy]

Re: Jono 55 idle / acceleration problem

1987 55hp. make sure the primer solenoid lever is in the totally closed position. are the Carb butterflies closing all the way at idle? very possibly needs linc n sinc procedure done again, since you have the motor apart.

 

[wojtech]

Re: Jono 55 idle / acceleration problem

I did have that problem once, caused by bad return spring and linkage bush on one of the carbs fixed that a while ago and synced them as best I could, both butterfly's close all the back evenly. I understand that scenario could cause bad idle but when I open the throttle wide it almost dies, I have to really pump throttle up/down for a bit to get it going and then when does get going I can wind back the throttle almost all the way boats slows and I can then gun it and it accelerates fine unless I run at idle for more than 5-10 secs.

 

[wojtech]

Re: Jono 55 idle / acceleration problem

Hey All, Looks like the fuel pump diaphragm was the problem, she purrs like a kitten now and throws me back in my seat.

Got a couple of barra as well when I went for the sea trial!!

Thanx for all your help! Take Care All.