One way check valve for fuel line
08-18-2019, 07:43 PM
#1
Advanced
Thread Starter
One way check valve for fuel line
(1994 LT1 Automatic) Has anyone installed a one way check valve on the Fuel Return Line? I recently had a faulty injector cause 1/2 tank of fuel to be siphoned into the engine overnight. Needless to say when I tried to crank the engine there was terrible noise and the engine was hydro-locked. Drained the oil and gas, pulled the engine and upon removing the oil pan, I noticed that the Blue FelPro Pan gasket had disintegrated. Had I known of the fuel being in the engine and just drained and replaced the oil and replaced the injector, all those pieces of the gasket would have plugged the oil pump and destroyed the engine. I have always had piston slap so I decided to have the engine rebuilt and want to install a one way check valve on the fuel return line so this doesn't ever happen again. I am seeing one way check valves but they state they are for low pressure fuel lines. I am thinking it should work for the return line but I am not sure how much pressure that line has. The check valve would also aide when changing the fuel filter, because before I learned the trick of pulling the fuel pump fuse and trying to start the engine to prevent the return hose from siphoning, I took a bath in gas while under the car. So has anyone tried this and/or is this a good idea??
08-18-2019, 08:28 PM
#2
Advanced
Thread Starter
The reason I am asking is that somewhere I read that the Return Line somehow was the cause for the siphoning effect, but I cannot find that post. If I am wrong on that point, my check valve would be useless.
08-18-2019, 11:25 PM
#3
Safety Car
The return already has a one way check valve, the regulator will close and seat itself when there is no fuel pressure and the fuel could not siphon. I do not think this is your problem.
Last edited by bjankuski; 08-18-2019 at 11:26 PM.
08-19-2019, 10:18 AM
#4
Race Director
No doubt you had gas in the crankcase, but 8 gallons?
08-19-2019, 06:59 PM
#5
Advanced
Thread Starter
I filled it up on the way home so it was full and a half tank was showing on the gauge, so I would guess about 6 gallons. The injector #7 was wide open when I tested it without power so the siphon effect filled everything through #7. I drained the oil into a large radiator drain pan and I had to empty it twice and there was gas in the exhaust pipes. Had I not cranked it there probably would not have been mechanical damage, but the pan gasket deteriorating would have taken the engine out. I did not see any fuel in the regulator vacuum line, probably can test the diaphragm with a vacuum pump to see if it leaks??
08-19-2019, 10:55 PM
#6
Race Director
The injectors are located in the top of the motor. The fuel tank is below that. Did you park in a steep hill? Your injector is rated a 22 gallons/hour. If you drove 15 minutes home, you could have used up your 6 gallons if the injector was stuck open.
08-20-2019, 10:09 PM
#7
Advanced
Thread Starter
Not that it matters at this point, the gas station is one block from my home. I drove directly home with a full tank of gas and the engine was running fine. The next day after trying to start it and it hydro-locked is when I noticed the gas smell and saw the gauge showing approximately 1/2 tank. Even though the fuel lines are on top of the engine, I challenge you to kill your engine and disconnect the fuel line at the fuel rail and watch it empty your tank. At first the oil and gas mix came out then it was pure gas, if I had gotten another clean drain pan, I could have had saved some 93 octane for my mower, hind sight 20/20.