m16ty Posted July 18, 2018 Share Posted July 18, 2018 On my RD822sx, E9, if she sits for about a week, you have to give it a sniff of either to get it to start. If you start it every few days it starts fine. Sounds to me like it’s loosing prime. I’ve gave the fuel system a look over and see nothing obvious, anybody have any idea what it could be? Quote Link to comment https://www.bigmacktrucks.com/topic/53841-e9-loosing-prime/ Share on other sites More sharing options...
AZB755V8 Posted July 18, 2018 Share Posted July 18, 2018 (edited) It can be as simple as the fuel return restrictor valve, back to the tank on side of pump, leaking down. This will drain the fuel from the pump galley. Easy way to tell is put a galley pressure gage in to a port or tee into supply line from charge pump, I have the gage in my dash now. After mine sits it will pop-off easily with 6 cyl then when galley pressure is above 5psi the others cylinders chime in. In the transfer pump there are 2 disk return check plates, usually a fiber disk with small spring, that can be worn and can leak fuel back to the tank that way too. Last thing if you have a hand primer on your transfer pump the shaft seal can be leaking air back in to system when truck sits a lot. It will leak air in as it is the highest point in the fuel system and not fuel out. I replaced the return valve and primer so last is the transfer pump. Once it takes more than a second for the engine to fire up and other cylinders to catch in 5-10 seconds. Edited July 18, 2018 by AZB755V8 2 Quote Link to comment https://www.bigmacktrucks.com/topic/53841-e9-loosing-prime/#findComment-402637 Share on other sites More sharing options...
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