fuel pump check valve???
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Joined: Dec 2001
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From: Louisville,Ky.
fuel pump check valve???
Working on a 88 Ranger 2.9L 5-speed ext cab.
The fuel pressure drops off fairly fast when turned off and I'm pretty sure that the check valve is bad. My question is, which pump has the check valve? It is a single mid tank set-up and has a pump in the tank and on the frame.
Pressure is fine while running. about 30psi @ idle and 40psi with no vacuum on the regulator. The pressure drops off within a couple of minutes which causes it to have to crank over for a bit to rebuild pressure and start.
It looks like the frame pump is readily available while the in take pump is special order. I just need to know which one has a check valve. I'm thinking the in tank pump, but I hate to waste $100+ for the wrong pump. It's my father in-laws truck and is is very good shape other than this hard starting problem.
Thanks,
Jimmy
EDIT: Pressure drop rate
30 psi @ shut off
25 psi @ 1:05 min
20PSI @ 2:30 min
15psi @ 4:45 min
still dropping
The fuel pressure drops off fairly fast when turned off and I'm pretty sure that the check valve is bad. My question is, which pump has the check valve? It is a single mid tank set-up and has a pump in the tank and on the frame.
Pressure is fine while running. about 30psi @ idle and 40psi with no vacuum on the regulator. The pressure drops off within a couple of minutes which causes it to have to crank over for a bit to rebuild pressure and start.
It looks like the frame pump is readily available while the in take pump is special order. I just need to know which one has a check valve. I'm thinking the in tank pump, but I hate to waste $100+ for the wrong pump. It's my father in-laws truck and is is very good shape other than this hard starting problem.
Thanks,
Jimmy
EDIT: Pressure drop rate
30 psi @ shut off
25 psi @ 1:05 min
20PSI @ 2:30 min
15psi @ 4:45 min
still dropping
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
The check valve is in the pump on the frame.
If you are saying it drops to 15 psi in 4 hours and 45 minutes that should be OK.
It will to zero over night but the fuel lines should remain full of fuel so that the one second the pumps run when the key is first turn on should bring it back up to the ~32-40 psi to start the engine.
If you are saying it drops to 15 psi in 4 hours and 45 minutes that should be OK.
It will to zero over night but the fuel lines should remain full of fuel so that the one second the pumps run when the key is first turn on should bring it back up to the ~32-40 psi to start the engine.
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
I take it the check valve was good in the old frame mounted pump.
I take it you did not try to blow air back through the frame pump after you took it off.
So then either the Fuel Pressure Regulator is not seating or the injectors are leaking then.
I take it you did not try to blow air back through the frame pump after you took it off.
So then either the Fuel Pressure Regulator is not seating or the injectors are leaking then.
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Moderator
Joined: Dec 2001
Posts: 22,436
Likes: 17
From: Louisville,Ky.
I'm leaning towards the regulator myself. It seems a bit slow to react when you mash the throttle. It climbs, just slowly.
No, I should have checked the old pump, but took a gamble and lost.
It doesn't act like an injector because it doesn't puff rich on start-up and acts like there is air in the line when it first starts then smooths out after about 5 seconds. Never smells rich like the fuel is in a cylinder either.
I have access to a 90 4.0 truck. I'm going to check to see if the regulators are the same before shelling out another $75 for a new one.
I appreciate your help Bill!!
No, I should have checked the old pump, but took a gamble and lost.
It doesn't act like an injector because it doesn't puff rich on start-up and acts like there is air in the line when it first starts then smooths out after about 5 seconds. Never smells rich like the fuel is in a cylinder either.
I have access to a 90 4.0 truck. I'm going to check to see if the regulators are the same before shelling out another $75 for a new one.
I appreciate your help Bill!!
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
When you take the Fuel Pressure Regulator off put about 40 PSI air pressure on the Fuel inlet tube and see if it leaks out the outlet tube and none out the vacuum tube (should not pass air until 45 psi).
If no leaks @ 40 psi I would say it is a good one.
/
If no leaks @ 40 psi I would say it is a good one.
/
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Thread Starter
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Joined: Dec 2001
Posts: 22,436
Likes: 17
From: Louisville,Ky.
Twas the regulator. It's weird because the pressure still drops off fairly fast, but with the new regulator, the rail stays full and it starts right up. It even fired right up this afternoon after sitting since yesterday evening.
4.0 was different, had to get a new one.
Thanks for the help!!!!
4.0 was different, had to get a new one.
Thanks for the help!!!!
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