I rebuilt my 4 barrel carburetor on my '75 Ford pickup 390 engine. It ran good for about 1 day then I noticed the fuel pump was leaking so I replaced it. When I started it, it ran for 5 minutes real good then the RPM dropped and ran rough for 10 seconds then it increased for about 10 seconds then decreased and keeps this up continually. I checked the finger screen at the inlet of the carburetor and it was clean, no debris from fuel pump diaphragm like I thought there may be.
Not sure what's causing this fluctuation. It worked OK after I rebuilt the carburetor and prior to changing the fuel pump. Any help would be greatly appreciated.
2007-07-29 09:10:03 · 4 answers · asked by TheJMeister88 2 in Cars & Transportation ➔ Maintenance & Repairs
sounds like a vaccum leak or air leak someplace. make sure the bolts are tight on the carb and fuel pump.
2007-07-29 12:10:30 · answer #1 · answered by mister ss 7 · 0⤊ 0⤋
Check the floats and readjust the idle mixture. Don't forget to retorque the carb after running it. The temperature difference (especially in dissimilar metals) will cause the tolerances to change and it won't seal.
2007-07-29 16:18:45 · answer #2 · answered by blueshiva7 2 · 0⤊ 0⤋
could have gotten some dirt in the carb. or IT could be sucking air around the fuel pump. or maby the fuel pump is defective. good luck
2007-07-29 16:15:09 · answer #3 · answered by doug h 5 · 0⤊ 0⤋
Gas in the oil. (smell it)
2007-07-29 16:19:23 · answer #4 · answered by Mr. KnowItAll 7 · 0⤊ 0⤋