VAPOR LOCK
I'm experiencing what I believe is vapor lock in my 1990 E350 Class C. Happens when I climbing hills, especially when it's hot out. I can see the engine temp gauge rise and start looking for a wide p...
Forum Discussion
I looked up 1990 E350 chassis and proceed on the (always risky) assumption it's 460-V8-EFI. If so, it uses two, maybe even three, electric fuel pumps. One Low Pressure Pump PER TANK, then a High Pressure External pump. The only external high pressure one I ever dealt with was frame-mounted on a T-Bird. Ford shortly after eliminated the frame-mounted and moved the high pressure pumps to the fuel tank(s). I think that by the year they went EFI on the 460 in E350 (which was 1989 Chassis Year, very possibly what's under your 1990 coach), most of tham had one large gas tank instead of the two-tank setup common in the early and mid-1980s.
It sounds like you replaced the frame-mounted high pressure pump, and most likely the associated filter. Change the filter if you have not, and see if there's a Pressure Test Point where you can measure pressure at the Throttle Body (or Fuel Rail). Takes a Fuel Pressure Gauge, I think 40PSI or a little higher. But you may have a failing Low Pressure, In Tank pump. If you change it, you must change its strainer too.
Overheating... Do you have a factory Fan and Thermostatic Clutch setup? And are you gearing down? On a steep hill, you should be in Second Gear, around 45MPH, engine winding up, and the Fan Screaming. Needs to be Factory Fan with a good Factory type Thermostatic Clutch. Aftermarket "viscous" clutches and "Flex Fan" conversions won't hack it. Radiator needs to be clean in and out, Thermostat opening wide. And exhaust can't be crimped or plugged.
It sounds like you replaced the frame-mounted high pressure pump, and most likely the associated filter. Change the filter if you have not, and see if there's a Pressure Test Point where you can measure pressure at the Throttle Body (or Fuel Rail). Takes a Fuel Pressure Gauge, I think 40PSI or a little higher. But you may have a failing Low Pressure, In Tank pump. If you change it, you must change its strainer too.
Overheating... Do you have a factory Fan and Thermostatic Clutch setup? And are you gearing down? On a steep hill, you should be in Second Gear, around 45MPH, engine winding up, and the Fan Screaming. Needs to be Factory Fan with a good Factory type Thermostatic Clutch. Aftermarket "viscous" clutches and "Flex Fan" conversions won't hack it. Radiator needs to be clean in and out, Thermostat opening wide. And exhaust can't be crimped or plugged.
