Johnson GPX71 surging

[aksparks]

starts & idles fine, after aprox 6-8 sec under full power, starts surging like it is running out of fuel. back off throttle a little and runs just fine. tried different hose, primer bulb, fuel pump changed small fuel lines on carbs, different tanks. help?

 

[cotterman]

Re: Johnson GPX71 surging

check fuel filter?

 

[Fouled Plug]

Re: Johnson GPX71 surging

All tanks venting properly?

 

[P.V.]

Re: Johnson GPX71 surging

What's a "GPX71"???

 

[aksparks]

Re: Johnson GPX71 surging

GPX71 is the model on the cowl. I believe it is a 70 hp 3cyl. I have checked the venting on both tanks. The filter is clean. Is there a way to check fuel pressure near the carbs while running? If so, what should it be? thanks

 

[papasage]

Re: Johnson GPX71 surging

am having the same probablem with my 1979 55 hp. it is usealey on the first full throttle let off a little it will run fine .changed tank new hose took the fuelpump off a motor that is running good cleaned the carbs . will keep checking back to se if anyone knowes the probablem or if i figure it out i will post it. papasage>>>>>>>>>>>>