fuel pump
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Senior User
Joined: Apr 2006
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From: houma, louisiana
fuel pump
1985 f350 6.9 i put a fuel guage to check the fuel pressure, with spinning it over it flucuates between 4-5 pounds. it doesnt have a steady pressure is this normal? if i start the engine, engine running it reads 4-5 pounds. is my fuel pump bad are is this normal. thanks for any replies.
Post Fiend
Joined: Nov 2004
Posts: 5,638
Likes: 1
From: Manitoba
You have done half the test...............do the rest for flow.
Take the Schrader valve core out and hook a hose and pressure guage to the outlet.........crank engine see what you get for pressure, should have 4-6 psi from a good lift pump.
Volume test same place hook a hose to it crank over the engine 10 seconds you should get 1/3 pint of fuel minimum or 1 pint at 675 rpm in 30 seconds... engine running
Important the fuel shutoff solenoid (FSS) wire on the IP should be disconnected if you do not want a start just cranking. Re connect FSS after test complete.
Take the Schrader valve core out and hook a hose and pressure guage to the outlet.........crank engine see what you get for pressure, should have 4-6 psi from a good lift pump.
Volume test same place hook a hose to it crank over the engine 10 seconds you should get 1/3 pint of fuel minimum or 1 pint at 675 rpm in 30 seconds... engine running
Important the fuel shutoff solenoid (FSS) wire on the IP should be disconnected if you do not want a start just cranking. Re connect FSS after test complete.
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Senior User
Joined: Apr 2006
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From: houma, louisiana
thanks plc7.3 i did the flow test the same time i did the pressure test and every thing turned out allright. the question i have is does inside the fuel pump is there a check valve that does not let the fuel leak back to the tank? after i let it sit for overnight the line coming from the pump to the ip looses the fuel but i dont see any on the ground. what could be causing that?
Post Fiend
Joined: Nov 2004
Posts: 5,638
Likes: 1
From: Manitoba
Our fuel system is a complete circle and will remain full, AS LONG AS THERE ARE NO AIR LEAKS. Air will go into the system where diesel will not leak out, this allows the fuel system to drain off. Do you see any areas on the engine fuel system where diesel is leaking.......
Visit..........http://www.intellidog.com/dieselmann/idi.htm read all about air leaks.
Visit..........http://www.intellidog.com/dieselmann/idi.htm read all about air leaks.
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Senior User
Joined: Apr 2006
Posts: 478
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From: houma, louisiana
see no wet spots on the ground . the return line that comes from the fuel filter housing to the #1 injector, does it have to be removed or can i leave it if i replace all the lines and fittings ?
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