Help, No Fuel Pressure!

[TheWiz]

My brother has a 2000 Ford Explorer 4.0L OHV that was running really bad and dieing all the time. The garage said it needed a new fuel pump.

With a new pump and filter it ran great for one day and then started idling real rough and dieing again. I bought a gauge to test the pressure, with key at on position I can hear the fuel pump but get no readings at the fuel pressure gauge. Cranked the engine and while it tried to start the gauge read around 20 psi.

I disconnected the fuel line before the filter and turned the key to on, fuel came squirting out. Disconnected the fuel line after the filter and fuel squirted out of the filter.

I thought it might be the fuel pressure regulator but I guess this thing doesn't have one?

I'm not sure what to do next except maybe replace the pump again but it seems to be working.

Any help would be greatly appreciated!

 

[MBeaston]

My brother has a 2000 Ford Explorer 4.0L OHV that was running really bad and dieing all the time. The garage said it needed a new fuel pump.

With a new pump and filter it ran great for one day and then started idling real rough and dieing again. I bought a gauge to test the pressure, with key at on position I can hear the fuel pump but get no readings at the fuel pressure gauge. Cranked the engine and while it tried to start the gauge read around 20 psi.

I disconnected the fuel line before the filter and turned the key to on, fuel came squirting out. Disconnected the fuel line after the filter and fuel squirted out of the filter.

I thought it might be the fuel pressure regulator but I guess this thing doesn't have one?

I'm not sure what to do next except maybe replace the pump again but it seems to be working.

Any help would be greatly appreciated!

Sounds To Me Like It May Be Bad Injectors Or Plugs And Wires.... When it was running was your check engine light on? if so did you plug an obd II scanner in and check the codes?

 

[BrooklynBay]

Welcome to this forum! Did you ever use fuel injector cleaner? When you tested the pressure, did the pressure bleed off very fast? It's possible that you might have a leaking injector with some partially clogged injectors. Does the engine appear to be flooded with a strong fuel odor?

 

[MBeaston]

Welcome to this forum! Did you ever use fuel injector cleaner? When you tested the pressure, did the pressure bleed off very fast? It's possible that you might have a leaking injector with some partially clogged injectors. Does the engine appear to be flooded with a strong fuel odor?

That was my thoughts also BrooklynBay

 

[TheWiz]

Thanks for the quick reply!

The garage read the codes but said it needed a new fuel pump before getting to anything else. The codes are PO102, PO113, PO171, and PO174.

I don't understand what the plugs, injectors or wires would have to do with no pressure reading at the rail.

I believe it's supposed to read around 62 psi with the key in the on position, my gauge reads 0.

Thanks!

 

[MBeaston]

your gauge reads zero because the fuel pump only turns on momentarily to prime the system when you turn the key forward you get pressure while you spin the motor over because the fuel pump is re-activated... it may be a bad relay also try swapping out your headlamp relay with the fuel pump one and see if that helps the relay might not be completely shot but could be causing not enough power to flow to the pump to run the pump strong enough also you really only need about 15lbs of fuel pressure and stock injectors i believe are for 15lbs of pressure

 

[BrooklynBay]

Did you bypass the fuel pump relay to test the pressure? The computer only lets the pump run for a few seconds when you turn the key.

 

[MBeaston]

Did you bypass the fuel pump relay to test the pressure? The computer only lets the pump run for a few seconds when you turn the key.

Wow We Think Alike

 

[BrooklynBay]

It's scary.

 

[TheWiz]

I'm not an expert so I'm not sure how to bypass the relay, lol.

I don't see any headlight relay in the power distribution box to swap with the fuel pump relay. The garage said they swapped relays and they were fine, that was why they recommended a fuel pump replacement.

Thanks!

 

[BrooklynBay]

The relay has two thin wires for the coil, and two thick wires for the contacts. Bypass the thick wires with a piece of wire. You will hear the pump run continuously.

 

[MBeaston]

I'm not an expert so I'm not sure how to bypass the relay, lol.

I don't see any headlight relay in the power distribution box to swap with the fuel pump relay. The garage said they swapped relays and they were fine, that was why they recommended a fuel pump replacement.

Thanks!

do you have a test light if so ill tell you how to bypass it?

 

[MBeaston]

The relay has two thin wires for the coil, and two thick wires for the contacts. Bypass the thick wires with a piece of wire. You will hear the pump run continuously.

i was gonna say use a test light to figure which was the positive input first then do a direct jump from the battery to the one that runs to the pump its self

 

[BrooklynBay]

Was the voltage tested at the fuel pump? The pump might only see 6 volts instead of 12 volts, and run with low pressure. Corrosion on contacts, bad wiring or a bad inertia switch might contribute to the loss of voltage. What about your battery terminals or fuses? Are they corroded?

 

[MBeaston]

my fuel pump presses about 28lbs of fuel pressure give or take a lb

 

[TheWiz]

my fuel pump presses about 28lbs of fuel pressure give or take a lb

Is that with the engine running or just the initial pressurization?

I found a test light.

I'll go try and check the voltage at the pump.

Thanks for all the help!

 

[MBeaston]

Is that with the engine running or just the initial pressurization?

I found a test light.

I'll go try and check the voltage at the pump.

Thanks for all the help!

that's pressure for both but yours pushing 20 lbs is plenty mine pushes more because i have an external fuel pump i believe your fuel pump is working fine if it gives you pressure as you spin the motor over i highly believe that your problem is in your injectors i would pull them out and take a look at them for corrosion

 

[TheWiz]

Someone stole the battery out of my multimeter

From what I've read, with the key in the on position the fuel pump turns on briefly to pressurize the system and I should see some reading at the rail test port. I just don't get why I see nothing.

I wish I had the money to just drop it off at the garage.

Thanks for all the help!

 

[TheWiz]

Ok, I tested the voltage at the wiring that runs into the tank. Got 12V.

I jumped the relay and got a reading of about 14psi on the gauge.

Thats too low isn't it? Could the fuel pump have gone bad in one day? It's an Airtex from Autozone.

Thanks!

 

[MBeaston]

Ok, I tested the voltage at the wiring that runs into the tank. Got 12V.

I jumped the relay and got a reading of about 14psi on the gauge.

Thats too low isn't it? Could the fuel pump have gone bad in one day? It's an Airtex from Autozone.

Thanks!

Try Hooking The Pressure gauge up before the fuel filter then tell me how much pressure you have