'99 Big Boss 6x6 500cc(A99AE50AA)

Toyogiken fuel pump
Mccooney carb

Problem just started... Was fine last week?

Starts fine
Idles fine
Give 'er gas (High RPM), sputters, pops, backfires, no power?

Need some help here!

Bad gas?
Poor spark?
Sucking air somewhere?
Bad pump? > Toyogi Ken (sp?)
Fuel filter (Seems Clean)
Carb out of adjustment? The Haynes manual is really vague, with the howto's!! > McCooney (sp?)

Where to start and processes to isolate the problem(s) PLS, it's getting really cold up here to work outside?

b

 

Pull the valve cover and inspect the valve clearance(.006 intake and exhaust) BUT mainly inspect the exhaust cam lobe in the middle. It should be egg shaped the same as the two outer intake lobes. A of of times they are ground down to nothing over a period of time which can cause a good idle,but back fire when you give it throttle and will have no power. This was in the year range of the soft heat treated cams (1996-2000 model 500s) Eliminate the cam as a problem first,then you can address fuel,spark related problems next if necessary. OPT