Fuel question

[Mike "Hubbie" Stearns]

I have a 28 truck with a fuel tank that is higher than the carb. The original engine was gravity fed. I have changed out the engine ti an ih rd450 that has a mechanical fuel pump. I do have a shut off valve at the tank. The bottom of the fuel tank is about 6 inches above the carb. The question is should I put something before the fuel pump to keep the it from flooding itself out ?  The tank is 16” tall. Thanks in advance Mike 

[Str8-8-Dave]

Mike- not real familiar with your IH engine but the carburetor must have a float valve in it.  The float valve should be able to prevent flooding under most any circumstance with the original mechanical pump.  If you had a high pressure electric fuel pump that might be an issue but the carburetor float valve, if healthy, would have been designed to shut fuel off when the bowl fills under full mechanical pump pressure.  Also the spring loaded check valves in the fuel pump may represent enough restriction to stop fuel from flowing with a full tank of gas that is above the level of the fuel pump.  You could try loosening the fuel line from the fuel pump to the carburetor to see if gravity fed fuel pressure from your particular tank arrangement can flow thru the mechanical pump with the engine stopped.

 

One other famous booby-trap with mechanical fuel pumps that haven't been rebuilt in awhile is diaphragm rupture.  If the fuel pump diaphragm has a small hole in it, it will likely pump raw fuel into the crankcase which is not good for the engine and can be a fire hazard.  You should consider researching and finding an overhaul kit for the fuel pump that has a diaphragm that will not be affected by today's ethanol fuel concoctions.  Just my thoughts.

 

Dave..