Shut down

[tkswan]

02 LS V8 3.9L

I was driving yesterday and it shut itself down. it kept trying to start but wouldn't turn over. it did a couple of times but would barely run. I found that the 15amp fuel pump motor fuse was blown so i took a fuse from another place to see if it would start up and it blew that fuse too. I suspect the relays but cant really tell because they have no good/bad indicators. How do you test them?

[shorod]

Are you referring to fuse F4.17 in the Battery Junction Box? This 15A fuse provides power to the Rear Electronic Module (REM) via the Fuel Pump Relay. The REM then switches the fuel pump on or off. The relay itself is just a switch, if it were stuck open or closed, it by itself would not cause the fuse to blow. If F4.17 is blowing, it's not due to the relay. The relay would normally be closed at all times when the key is in RUN or START.

If it's a different fuse that's blowing, please post back with the fuse number. I'll be camping this weekend and won't have access to my service manuals, but someone else on this forum may be able to provide further information.

-Rod

[danielsatur]

A relay allows a small signal to trigger a large current device, a fuse is used for protecion in the circuit.

If you suspect the relay, it canbe rolled with another of same type in the fuse box.

1) Try another 15amp fuse, and check the fuel pressure with the Key On Engine Off (KOEO).

It sounds like a bad fuel pump, the fuel pumps canbe located under the back seat.

Also see Similar Threads @ the bottom of yours.

[tkswan]

Yes. The #17 15 amp fuse in the box next to the battery. The owners manual lists it as Fuel Pump Motor. So what do you think is causing the fuse to keep blowing? Fuel pump? Also, when i replaced with a good fuse and turned on the power to the car, I did not hear the normal hiss of the fuel system pressuring. When I tried to start the car the fuse blows. My Dad saw the spark of the fuse blowing.

[tkswan]

Originally Posted by danielsatur

A relay allows a small signal to trigger a large current device, a fuse is used for protecion in the circuit.

If you suspect the relay, it canbe rolled with another of same type in the fuse box.

1) Try another 15amp fuse, and check the fuel pressure with the Key On Engine Off (KOEO).

It sounds like a bad fuel pump, the fuel pumps canbe located under the back seat.

Also see Similar Threads @ the bottom of yours.

I did try another15 amp fuse. First thing I did last night. When I went to KOEO the fuse was ok. When I attempted to start the engine the fuse blew out, the spark was plainly visible because it was night time.

[danielsatur]

It sounds like a bad fuel pump, there's a short blowing the fuse.

How many miles are on this car?
Did you run out of gas prior?
Is the trunk dry?

[tkswan]

Originally Posted by danielsatur

It sounds like a bad fuel pump, there's a short blowing the fuse.

How many miles are on this car?
Did you run out of gas prior?
Is the trunk dry?

About 149k
Never ran it out of gas, I only run Chevron 93
trunk is dry

now to figure out which pump is the bad one,and are there any special tools or tips on replacing it.

[danielsatur]

Because of Age + mileage, it's probably time for a new fuel pump.
For a DIY, consider www.alldata.com for procedure.

www.autopartswarehouse.com prices for OE LS fuel pumps is from $60 Delphi to being $300 for a MotorCraft.

[tkswan]

Originally Posted by danielsatur

Because of Age + mileage, it's probably time for a new fuel pump.
For a DIY, consider www.alldata.com for procedure.

www.autopartswarehouse.com prices for OE LS fuel pumps is from $60 Delphi to being $300 for a MotorCraft.

how do i figure out which pump to replace?

[tkswan]

Originally Posted by tkswan

how do i figure out which pump to replace?

also i was reading some other posts on the subject and i am suspecting the primary pump because:
the car died while making a left turn from a stop,and will not start afterward. it started and ran badly the first second and third attempt but it seemed to be running on whatever fuel was left in the system.

when turning the car power on KOEO, i don't hear the hiss of the fuel system pressurizing.

So if the the jet pump is more of an assist pump for higher rpms, the primary is for lower idle, and charging the system for engine startup. does that make sense?

if the motor is out i should be able to do a simple power test without having to purchase a subscription to all data. ...shouldn't i?

[shorod]

I e-mailed you a wiring diagram and a short description of how you could confirm if it's the fuel pump, the REM, or the wiring. Even though I only addressed the main pump and not the jet pump, the same concept would apply. If you unplug one pump assembly and the fuse no longer blows, you've determined which pump is the culprit. Unfortunatly, since the REM controls the pump, you cannot just substitute a test light for the fuse and watch for a brightly glowing test light to become a dimly glowing light indicating the short has been removed. You'll want to buy a box or two of fuses.

-Rod

[tkswan]

Ok using common sense, if the jet pump is an assist pump to the primary pump, then the primary pump feeds the engine fuel rail. so it would make sense to believe that since the fuel lines to the engine are coming from the primary pump, the side of the tank with the fuel lines must be the primary pump side. does that make sense?

[tkswan]

Originally Posted by shorod

I e-mailed you a wiring diagram and a short description of how you could confirm if it's the fuel pump, the REM, or the wiring. Even though I only addressed the main pump and not the jet pump, the same concept would apply. If you unplug one pump assembly and the fuse no longer blows, you've determined which pump is the culprit. Unfortunatly, since the REM controls the pump, you cannot just substitute a test light for the fuse and watch for a brightly glowing test light to become a dimly glowing light indicating the short has been removed. You'll want to buy a box or two of fuses.

-Rod

Awesome, thanks. do you think im smart enough to replace a fuel pump without written instructions? ...i'm an old school military guy that used to assemble and dissemble tactical missiles and bombs so I religiously believe in the RTFM (Read The F**** Manual) rule. before starting any jobs you aren't familiar with

[danielsatur]

If the problem with fuel pressure over 2rpms, it's usually the jet pump.

[tkswan]

Originally Posted by danielsatur

If the problem with fuel pressure over 2rpms, it's usually the jet pump.

don't know because it won't start, it just blows the fuse.