No power to fuel pump
#1
No power to fuel pump
I recently bought a 2002 XLT 4.0 Ranger. The truck has 93,000 miles on it and had been sitting in a garage for three years without being started. The previous owner passed away and his wife told me it ran fine when it was parked. She said the truck just turns over but will not run. The truck has spark but I pushed in the Schraeder valve on the fuel rail and no gas came out of it. I checked the fuses and relays and they seem fine. The inertia switch by the passenger footwell seems fine as well. I changed the fuel filter and still had no luck. I have the bed removed from the truck now and the fuel pump does not seem to be getting power. I unplugged the harness to the fuel pump and put a test light on it with the ignition on and it seems no power is going to the pump. Anyone have any ideas what else I could look at?
#3
Check voltage with a multimeter at the inertia switch. It should show voltage for 2 seconds each time the ignition is turned on. If you have voltage at the inertia switch the next thing in line is the fuel pump.
You will only get voltage for 2 seconds so don't be fooled if voltage isn't showing constantly with the ignition in the on position.
You will only get voltage for 2 seconds so don't be fooled if voltage isn't showing constantly with the ignition in the on position.
#4
You are right. I put a test light on the harness for the inertia switch and turned the ignition on and the light came on for two seconds. Now I have to figure out why I am getting no power to the four pin harness at the fuel pump. I think the pink and black wire is the power for the fuel pump and the orange and black is the ground. I will have to research it more to be sure.
#5
I just went out and removed the fuel pump from the tank. I cut the wires that go to the pump itself and spliced an extension on them and hooked the pump directly to the truck battery. I would think that the pump would work or at least make some noise doing this. Maybe the pump itself is bad afterall.
#6
RF Veteran
iTrader: (1)
yes, pump is bad, they come on with 12volts
The cheaper fuel pumps have a 1 year warranty
Motorcraft(Ford) pumps have 90day warranty
I guess Motorcraft figures if it lasts the 90 days it is a good pump and will last for 20 years
So beware of long warranties, it seems to be more of a half life, lol, 1 year warranty = 2 year life
The cheaper fuel pumps have a 1 year warranty
Motorcraft(Ford) pumps have 90day warranty
I guess Motorcraft figures if it lasts the 90 days it is a good pump and will last for 20 years
So beware of long warranties, it seems to be more of a half life, lol, 1 year warranty = 2 year life
#7
#8
yes, pump is bad, they come on with 12volts
The cheaper fuel pumps have a 1 year warranty
Motorcraft(Ford) pumps have 90day warranty
I guess Motorcraft figures if it lasts the 90 days it is a good pump and will last for 20 years
So beware of long warranties, it seems to be more of a half life, lol, 1 year warranty = 2 year life
The cheaper fuel pumps have a 1 year warranty
Motorcraft(Ford) pumps have 90day warranty
I guess Motorcraft figures if it lasts the 90 days it is a good pump and will last for 20 years
So beware of long warranties, it seems to be more of a half life, lol, 1 year warranty = 2 year life
#9
#10
RF Veteran
iTrader: (1)
I would get the whole assembly but no reason you couldn't just replace the pump if it has a check valve for 70psi.
I believe stock '01 fuel pump would be about 100 Liters Per Hour(LPH)
The old system pumps, 40psi with return line, were 60LPH
Engine can only use what it uses in fuel, unless you turbo or super charge it, it can't use more.
So no reason for it.
And watch the volume numbers, i.e. LPH or GPH, and what pressure that number was done at, at 6psi there can be a lot more volume than at 70 psi, so 200LPH is meaningless unless there is a pressure number with it, i.e. 150LPH at 70psi
I believe stock '01 fuel pump would be about 100 Liters Per Hour(LPH)
The old system pumps, 40psi with return line, were 60LPH
Engine can only use what it uses in fuel, unless you turbo or super charge it, it can't use more.
So no reason for it.
And watch the volume numbers, i.e. LPH or GPH, and what pressure that number was done at, at 6psi there can be a lot more volume than at 70 psi, so 200LPH is meaningless unless there is a pressure number with it, i.e. 150LPH at 70psi
#11
#12
RF Veteran
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Fuel pressure regulator(FPR) used a return line to the fuel tank, it is vacuum operated.
When vacuum is high, i.e. at idle or while cruising, FPR is pulled open and most of the fuel is returned to the tank, when accelerating vacuum drops so FPR closes as engine fuel demand is higher.
On Fords this system used 35-40psi pressure at the rail, and fuel pump was always on if engine RPMs were above 500.
The pump itself creates the pressure, if you unplug the vacuum line on the FPR with engine idling you might see 42-45psi as that is all the pressure the pump can generate.
It was found that this type of setup created more fuel vapor in the tank and it also heated up the fuel a bit, not much but not 0 either, because fuel was circulating thru hot engine compartment then going back to tank.
EVAP system pulls that vapor into the intake to be burned, O2 should pick that up but it is an emissions issue just because of the extra vapor from the flowing fuel and the heat.
In the late '90's Rangers got the returnless system which uses no FPR, the computer does cycle fuel pump off and on based on sensor data, i.e. RPM, throttle position, MAF, but it is on most of the time to maintain the 65-70psi.
Because of the higher pressure a Pulse Damper was added at the end of the fuel rail, when fuel injectors open and close they create a reverse pressure wave in the rail, at specific RPMs and loads these waves could augment each other, making "superwaves" and this would effect actual pressure at the injectors causing misfires, the pulse damper is just a diaphragm so any pressure wave(s) can't reflect back.
It also has a vacuum hose attached but this is only there for safety, if diaphragm should leak it could cause a fire, vacuum hose would cause any leaking fuel to be sucked in to a running engine, or sucked in the next time the engine starts.
Either system has a check valve(back flow preventer) on the fuel pump to prevent loss of pressure when pump is off.
When vacuum is high, i.e. at idle or while cruising, FPR is pulled open and most of the fuel is returned to the tank, when accelerating vacuum drops so FPR closes as engine fuel demand is higher.
On Fords this system used 35-40psi pressure at the rail, and fuel pump was always on if engine RPMs were above 500.
The pump itself creates the pressure, if you unplug the vacuum line on the FPR with engine idling you might see 42-45psi as that is all the pressure the pump can generate.
It was found that this type of setup created more fuel vapor in the tank and it also heated up the fuel a bit, not much but not 0 either, because fuel was circulating thru hot engine compartment then going back to tank.
EVAP system pulls that vapor into the intake to be burned, O2 should pick that up but it is an emissions issue just because of the extra vapor from the flowing fuel and the heat.
In the late '90's Rangers got the returnless system which uses no FPR, the computer does cycle fuel pump off and on based on sensor data, i.e. RPM, throttle position, MAF, but it is on most of the time to maintain the 65-70psi.
Because of the higher pressure a Pulse Damper was added at the end of the fuel rail, when fuel injectors open and close they create a reverse pressure wave in the rail, at specific RPMs and loads these waves could augment each other, making "superwaves" and this would effect actual pressure at the injectors causing misfires, the pulse damper is just a diaphragm so any pressure wave(s) can't reflect back.
It also has a vacuum hose attached but this is only there for safety, if diaphragm should leak it could cause a fire, vacuum hose would cause any leaking fuel to be sucked in to a running engine, or sucked in the next time the engine starts.
Either system has a check valve(back flow preventer) on the fuel pump to prevent loss of pressure when pump is off.
Last edited by RonD; 04-19-2015 at 09:25 PM.
#14
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