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Bad fuel pump symptoms

How do i test the fuel pump

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I assume that you have fuel injection. Some cars allow you to put a pressure gauge on the fuel rail. If it takes you three times to start your car and you have over 100 thousand miles then you can pretty much say your pump is shot. Many times about 500 miles after a fuel filter change the pump will go out. A poor mans way would be to disconnect the fuel line and hold a finger over the line to see how much pressure is there. This is very dangerous because you could wind up with gas in your eyes or the car on fire. Fuel pressure requirements vary from car to car. Example, the Jeep Cherokee uses pretty high pressure and will not run unless the pressure is high.

Posted on Jan 14, 2014


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1 Answer

Where is the fuel regulator located? And how can I tell if it's bad

Some fuel regulators are located in the tank as part of the fuel pump assembly. If the fuel pressure regulator has gone bad, it can leak fuel in the engine, contaminating the engine oil.

Symptoms of a bad regulator is:
Poor gas mileage.
Smell of gas in the engine compartment.
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Jan 08, 2017 | Cars & Trucks

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Do I have a fuel pump fuse and where would it be at ?

Better to test the pump relay with a meter or a test light. The relay could have failed.
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Where is the fuel pump inertia switch on a 1993 geo prizm?

there is none. (why not post symptoms and let test find cause?)

toyota Corolla. is same.
4AFE engine
7AFE engine. always know what you have first. before diagnosing
NO transmission stated, making pump diagnosis hard.
engine problems. (no starts?) is that it?
is fuel pump dead, that it>?
the car has a Fuel pump relay, only
and is controlled by many things,

the 4a engine, the Clutch or A/T tranny ignition ACTIVE wire,
feeds the Fuel pump relay , if the FP relay drops out ?
check voltage on both pins on the FP relay.
one side is grounded other is 12vd key on. if not , you lost power to it.
fuse blow? is 1st on all electrics, and same with EFI
im in the FSM and it shows no Inertial switch in the schematic.
but i see some sell it. for cars not in the USA. so????

let me now guess, the true post.
car will not start. but runs for 3 seconds on test fuel
owner cant hear pump
so find 0v across the pump cranking,
so the Fuel pump relay is dead. (not bad just dead)
why, so he finds the car is A/T tranny and checks the PRNDL switch there and is bad, or not bad and find the wire to it dead.
he finds a connector to the PRNLD bad. kiling the pump relay.
got a voltmeter? this is easy
check pump voltage cranking.

May 03, 2014 | Geo Prizm Cars & Trucks

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Misfire p0303

Check wiring harness around and including plug to the coil pack. Also check fuel pressure with vehicle running. I'm not sure of the specs but, Iit should be around 35 to 40 psi. at idle, and 50 to 75 at higher RPM's. I've seen Fords run with a bad fuel pump and demonstrate these exact symptoms

Mar 06, 2014 | Ford Cars & Trucks

1 Answer

What are the sign's of your fuel pump going bad?

The most obvious bad fuel pump symptoms is your vehicle won't start, or it starts but does not run for very long before eventually stalling out. Your vehicle will act as though it is out of gas, even though the fuel tank is full. As the fuel pump attempts to feed the engine fuel, your vehicle may make bucking noises but will not spark up.
If you do suspect that you have symptoms of a bad fuel pump, you can listen to it to see if it is operating. Electric fuel pumps can be heard when you turn the ignition to the second position, so if you do not hear any sound coming from your fuel tank with the key turned, your fuel pump may have failed or the motor may have burnt out. Also, if you notice that the fuel pump is making an excessive whining noise, it may be a sign that the part is on the verge of failing.
Two common bad fuel pump symptoms that your vehicle may experience are engine misfire at higher speeds, or difficulty climbing hills. These symptoms are a sign that your engine is not getting enough fuel. If you are experiencing these symptoms, you may want to perform a fuel pump pressure test.
In order to perform a fuel pump pressure test, you will require a fuel pressure gauge. By inserting the gauge in the Schrader valve (usually located in the engine compartment), you will be able to determine if your engine is receiving adequate pressure of fuel from the vehicle's tank. The required pressure reading will be different for vehicle specific applications. Most repair garages have one of these gauges on hand to perform this test.
Your fuel pump may fail or become a faulty fuel pump for a number of reasons. Rust, debris and dirt may enter into the vehicle's fuel system, and may potentially be clogging the fuel filter or the fuel strainer. This does not allow enough fuel to pass through to the fuel pump which overheats the parts, causing damage. A second cause of fuel pump failure is damage to internal parts caused by small particles of dirt entering into the fuel pump. The fuel strainer and fuel filter were unable to keep these particles from entering into the fuel. Another major cause of a faulty fuel pump or failure is letting your gas level get too low. When the level of fuel is low, the fuel pump has to work much harder, becomes overworked, does not cool down properly, and as a result can be damaged. You should never let your fuel reach less than a quarter of a tank.

Sep 12, 2013 | 1995 Lincoln Town Car

1 Answer

Having problem with starting, appears it out of gas, or not firing, but will start if set for a while

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Jun 04, 2011 | 1998 Chrysler Concorde

1 Answer

My 2000chevy silverado wont stay running was told the air bank system not working so fixed that and didn't help fuel pump is good changed fuel filter and still not working. Thank u kj

Check for vacuum leaks. If its bad enough it can stall out the engine. Also what test were performed to test the fuel pump? I'm asking this because a fuel pump can appear to be working but if you have the incorrect fuel pressure this can cause your symptoms as well. Also check the fuel pressure regulator.

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2 Answers

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I know in the mid 1970s Chevy had a modulator chip inside the distributor that would cause the same exact symptom they cost around $25 and can be found at your neighborhood autoparts store.
A quick check for spark will tell you if this might be the problem

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5 Answers

How do you know if your fuel pump is going out

The best diagnostic for the fuel pump is a pressure test. Need to know the specs on it (should be around 40-60 PSI), hook it up to a fuel pump tester and there you go.

The symptoms the engine presents when a fuel pump is going bad could include:

- hard to start
- hesitation
- loss of power upon acceleration
- going dead at idle
- others...

But other problems could cause these same symptoms.


Aug 23, 2009 | 2000 Ford Taurus

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