Fuel pressure

[snoopy]

Hi i rebuilt my engine i had petrol in my oil and it washed the bearings. fitted a new solex car and fitted a rebuild kit to my fuel pump. With the info i had on the fuel pump spacer i bought the correct one thanks Wesk. had the engine running for about 3 hours all ok. Then i notice big end noise. found fuel in the oil again removed pump could not see any way the fuel could have got in there. going to borrow a fuel pressure gauge to see what i have going to the carb. does anyone know what the correct pressure should be. Thanks

[wesk]

The only two ways I know of to get gas in your oil is flooding during starting or through the fuel pump. If you used one of those NOS fuel pump kits then the rubber diaphram is not going to hold up to the unleaded gas we are using now. The fuel pump can loose gas to the oil pan through a leaky diaphram, leak in vent system or bad check valve.

M38 fuel pressure is 4 - 5 1/4 PSI @ 1800 RPM
(TM 9-8012 Page 151)

M38A1/M170 fuel pressure is 4 1/2 - 5 PSI @ 1800 RPM
(TM 9-8014 page 144)

Although TB 9-804-11 addresses the M38 fuel pump it can also apply to m38A1's that have the M38 pump installed. It describes the AC service bulletin that drills a relief passageway between the area below the fuel diaphram to the cam lever area.

Also if you rebuilt this pump yourself and did not use the manual you may have neglected to make sure the new diaphram was flexed full down before tightening the top cover screws. This will reult in excessive fuel pump pressure.

[snoopy]

guilty of tightening top when diaphram was flat. Will retighten correctly then check fuel pressure. The pump kit i used was a modern replacment.
Thanks again Wesk.