Ok I can't figure this one out and need a little help. I have a 85 CJ7 with a 258. The jeep has only 51K on it and is mostly stock. I recently put a new Weber 32/36 carb on it and a new fuel filter and pressure regulator (set at 4.5psi). I also replaced all of the vacuum lines. Here is the problem. Sometimes it fires right up, no problems, hesitation or anything. Other times it cranks over for 10-15 seconds before it fires. Either way when it's started it runs great, no misses, idles like dream, no stalling on take off etc. I think I am going to start with a new fuel pump (Carter P4070 with no regulator), any other ideas?
the fuel filter on my old jeep is a metal type filter,
it has one inlet in and two outlets out:
the outside outlet is to be positioned at 12:00 high, the center outlet is for fuel to the carb.
the outside outlet is to let gas vapor return to tank,
if the outside outlet is positioned other than at 12:00 high, after the vehicle sets for a long period of time, fuel can be syphoned out of the carb and sent back to fuel tank.
when you next try to start the vehicle, you will have to pump fuel back into the carb, this may take a bit of cranking on the starter to get the vehicle running.
however, after short periods of non run time, the vehicle will start right up as fuel has not had time to syphon out of carb back to the tank.
this may not be your problem, but you need to insure you have the fuel filter properly onientated.
if it does not fix your problem, (cold engine) set carb choke with one push of fuel pedal, then check carb to be sure the choke closed, if the butterfly did not close properly, this can make the vehicle hard to start. If choke is working properly, you might try a full tuneup and timing set.
driving these new vehicles with fuel injection that always start right up,
have made us tend to forget the good old days of carbs and choke settings.
Since im using a weber carb I don't need that type of fuel filter. The gas tank return is from the carbon canister and the carb has a line running from it to the canister. I really think that fuel is slowly draining (gravity) back down the line through the pump over ectended time periods and that it takes a few cranks to re-pressurize the line to the carb. According to weber they recommend the carter rotary high volume low pressure fuel pump for optimal performance.