Question about 2004 Ford F150

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Bad fuel pump on a f150 4.6l

Had a problem with fuel pump and was trying to find out the normal pressure I was told anything over 40psi is this correct.

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Over 40 is the correct answer, around 42-44 under a load.

Posted on Dec 22, 2008


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2001 acura mdx wont start. cant hear fuel pump.

going backwards, ? (yes, i to check volts first) but...
you check fuel pressure cranking, (is press in spec or not?)
the FSM covers this, 1/.2 the cars only get pump activation,,
cranking and running, never just key on (the fsm shows this fact, i didnt look for you)
Yours is older loop system, not dead head.
there are 5 test just for the pump, (actually more)
pressure cranking and running, (leakdown test and injector balance tests and shut test for loop version) on V6 that 6 +4 ,10 total tests.
once the gauge is in place we do all 10s tests on v6.

ok say my pressure spec. is 40psi cranking and i get 10.?

spec: 32-40 running, pSI, vac, hose conn. (cranking will be more)
in loop systems the cranking pressure is about 10 PSI more.
after it starts, the vacuum sucks pressure from say 50psi to 40.
(its also altitude compensating)

Voltage checks, (any voltmeter)
use a voltmeter to see if full power reaches the pump.
i check voltage and its 8v. (bad) cranking volts can be near 11v due
to battery load, 200amps or so... what i do is measure battery crank
voltage and expect same to pump , using the 0.5v rule. (drop)
the connector over here to pump is all corroded. ,,
fix that and bam, now full presssure
or i find a bad fuel pump relay, replace that and bam.
or i find 0v, to pump.
i find relay bad. (simple tests on relay) (its not bad ECU)
ok i find 12v. at pump. so what is wrong?, i check my fuel pressure
regulator at the fuel rail, its stuck wide open because the shunt test
passed (one of 4 tests above) so new reg and bam, 40psi to rail.
i can test the reg with my hand vacuum tool that all shops have.
i can see pressure, running and cranking and check fuel pressure
with no vacuum (50psi?) then pump it to say 20 "hg (simulates idle)
and see 40 pSI, and check the diaphram for leak down.
my reg was bad.
there are other tests:
1: fuel pump current. (if excessive, its a bad pump)
2: scope test or use a current probe on pump and see it spiking
like made, , it has bad commutator and will die so.

there great videos on all this at. Duane's site.

check the pump cranking

do not hot wire the fuel pump relay
if you slip 1/.8" you blow up a nice $400 ECU, (or more)
the ECU drives this relay (with a transistor, you dont want to explode)
if you feel compelled to hot wire things, disconnect the pump
and hot wire that.
now the relay.
it has 4 pins 12vdc in, 12vdc out to pump (contacts)
and 2 coil pins.
you put your meter to coil pins (across) i get 12v to coil cranking and running, that is the ECU working right
i get 12vdc in and zero out the contacts, the relay is bad.
lets say you see 3v out, that can be a shorted pump. or wire grounded out to pump. I check the current with my amp clamp and see 15amps
the pump is bad. most draw 4-6amps. normal.
i keep an open mind, what is bad, its only the pump 1/2 the time
or less. maybe 1/3? (reg, pump, wires and friends)
corroded connectors big time...some even burned up.

Feb 09, 2014 | 2001 Acura MDX

1 Answer

No fuel pressure unless running. 40psi when running. can't get rpms up enough to drive

pump on its way out tats wit happend to me new disel pump sorted tat

Jan 25, 2013 | Cars & Trucks

1 Answer

Fuel pump without enough psi. suggestions??

I am sorry to say that if the old pump was putting out 40psi then the pressure switch will need the same psi from the new pump.
With the psi les then what the computer knows the engine needs it will not allow it to start and run.

Jan 19, 2012 | Cars & Trucks

1 Answer

My ford expedition is skiiping specially when the gas tank is low of gas it running good and suddenly it skipps like it gets zero gas, can you help

check fuel pressure at the fuel rail. could be a weak fuel pump. fuel pump 35 - 40psi. and or you might have a bad coil pack or sparkplug

Jul 27, 2011 | 2000 Ford Expedition

1 Answer

It starts when I used fuel starting spray, then it quit when the starting fuel is gone.

Bad Fuse,pump relay,Fuel filter,weak fuel pump,pluged fuel filter in the tank.bad pressure regulator,check to see if the pump runs in the should here it run while you crank the engine. if you can then check the should be open,not restricted.then check fuel pressure,at the fuel rail,with a guage 36 to 40psi is normal. Any less pressure will give poor performance.Check to see if the pressure regulator is or has ben leaking gas into the vacumn line to the intake manifold,if you can see smell,or detect any raw gas i would suspect a faulty pressure regulator.And it may be returning the fuel pressure back to the tank instead of controlling the fuel pressure to run the engine.

Sep 08, 2010 | Ford Explorer Cars & Trucks

1 Answer

Starting car is problem. it will start after maybe two trys. i have tried engine cleaner, but still it is slow starting,. battery is good, thats been checked.

When you have an engine that is hard to start or the engine takes longer than normal to start, with a fuel injected engine it will normally be caused by a fuel problem. Another problem would be slow cranking of the engine because of a low battery, I would check all of the fuel related problems if the engine seems to crank normally. There are a few things to check. First pull the fuel filter off and wipe it off so you don't get gas in your mouth and try to blow through one of the fuel connections on the filter. If you can't blow through it the filter is pluged and needs to be replaced. A plugged fuel filter can cause hard starting and can also damage your fuel pump. The next thing to do when everything is put back on the car is to check the fuel system for bleed down. You need to locate the fuel pressure test connection on the engine. Connect a fuel pressure gauge to the connection and start the engine, then turn the ignition off. With the engine off the pressure should read and stay between 30psi and 40psi, to be sure of the pressure you will have get the spec's on the engine you have. The main thing you will be looking for is to make sure the pressure doesn't start bleeding down in to direction of zero after a few minutes or maybe even immediately. If you see the pressure start to bleed down you have a problem. There are two problems that normally cause the pressure to bleed down. One is a bad check valve in the fuel pump, the other is a bad fuel pressure regulator. The main thing that happens with a fuel pressure regulator is the diaphram inside starts leaking. When that happens sometimes it will leak fuel into the intake manifold through the vaccuum hose connection to the intake manifold. To check for a fuel leak through the vacuum hose connection, locate the vacuum hose on the fuel pressure regulator and pull the hose from either the manifold connection or from the connection at the fuel reguator. If you see any gas at all the fuel regulator is leaking and must be replaced. If it is a slow leak from the regulator you might have to start the engine with the vacuum hose disconnected and look for a leak from the hose. If you don't find anything wrong with the regulator the next problem area would be fuel pressure bleeding back into the gas tank because of a bad check valve in the fuel pump. If this is the problem the fuel pump would have to be replaced. My first guess as to what is causing your problem would be the fuel pressure regualtor although I would definately want to make sure the fuel filter is not plugged. (Please Note) The fuel pressure regulator is located in the intake manifold area of the engine. The fuel pump is located in the gas tank. The fuel filter is located usually somewhere under the car.

Aug 24, 2010 | 2001 Pontiac Grand Am SE

3 Answers

1995 camaro fuel pressure

With the key ON engine OFF K.O.E.O. (cycle the key ON-OFF several times as pump only runs for 2 seconds) the pressure should be 41-47 PSI

May 12, 2009 | 1995 Chevrolet Camaro

1 Answer


if it is a v6 vortex you need 60 psi to run vehicle, could be a bad spider assembly(fuel injector unit)

Nov 26, 2008 | 1998 GMC Blazer

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