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Fuel pump relay?

Tiny
RJC9558
  • MEMBER
  • 1999 FORD TAURUS
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 39,000 MILES
Is there any way to test a fuel pump relay? I'd rather find out if that is my problem before replacing the fuel pump. The car cranks but won't start. And also, if I ran an OBDll on it, would it show specifically a relay, or just a fuel error?

Thanks for your help and your expertise!

Mark

ps. Forgot to mention it is getting spark.
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Thursday, January 8th, 2009 AT 9:56 PM

39 Replies

Tiny
IMPALASS
  • MECHANIC
  • 3,112 POSTS
Hi Mark

I have attached some checks for you.......

I know you said fuel, but are you sure? If not, we need to figure out if it is electrical or fuel related. Pull a plug wire off of the spark plug and insert something into the end of it and have someone try to start the car and have the metal object really close to a piece of metal on the engine and see if you are getting a good strong popping blue spark. Don't have your hands on any part of the metal! If there is no spark, then it is electrical.

If you are getting good spark then spray some starting fluid in the throttle body and try to start it and see if it tries to start then.

You may need to get a fuel pressure check on the fuel pump to ensure it is putting out okay.

Next I would still pull the codes on the car. A bad crank sensor will also not let the car start. Most important: Once you check your codes, if you find something and you don't get it fixed and need to get back with us, please make sure you tell us exactly what the code was, number and all. Example, if the code was E0568 O2 Sensor bad.
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Thursday, January 8th, 2009 AT 10:09 PM
Tiny
IMPALASS
  • MECHANIC
  • 3,112 POSTS
Hello -

Sorry Mark

I forgot to attach the location. . .. . .. . ...

And if you do get back with us please let me know your engine size in liter and the 8th digit of your VIN. Also is your model a LX, SE, or SHO


https://www.2carpros.com/forum/automotive_pictures/248015_4_46.jpg

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Thursday, January 8th, 2009 AT 10:13 PM
Tiny
TONZIT
  • MEMBER
  • 1 POST
  • 1998 FORD TAURUS
1998 Ford Taurus 6 cyl Two Wheel Drive Automatic

I lost my owners manual and the sticker by the relay says to consult owners manual to reset can you tell me how to go about that without replacing pump? I will replace pump if need be but wanted to try this first.
Thanks,
Tonya
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Wednesday, May 20th, 2020 AT 1:04 PM (Merged)
Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS
What is the issue?
No fuel pressure !
Check switch in the trunk
check for power at the pump when 1st key on
and or when cranking
try hit the gas mid of gas tank with hand as a helper cranking is start for sure fuel pump no good

good luck
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Wednesday, May 20th, 2020 AT 1:04 PM (Merged)
Tiny
KIRBYMURPHY
  • MEMBER
  • 7 POSTS
  • 1998 FORD TAURUS
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 110,000 MILES
It started with the 30 degree weather, but maybe it's a coincidence. Hot or cold, sometimes the car won't start. Cranks fast, no battery problem.

This morning it wouldn't start. Ambient temp about 25 degrees in the garage, but it failed last week after it was warmed up and about 40 degrees.

Couldn't hear the fuel pump when I turned on the ignition. Swapped the AC clutch relay with the fuel pump relay (same Part#) and it started. Maybe another coincidence? Replaced the relay and it still starts OK.

After reading many forums, the IAC (Idle Air Control)sounds suspicious. It has an occasional problem with the engine racing, about once a month.

Other forums mentioned the Mass Air Sensor as a possibility. Would that or the IAC prevent the fuel pump from getting energized?

EDIT: Just tried to start it again and couldn't hear the fuel pump and it wouldn't start. :(
Never got a check engine light, no codes.
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Wednesday, May 20th, 2020 AT 1:04 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
IF you don't hear the fuel pump again, something tells me the relay is bad and working when it wants. Try switching them again and let me know if it starts. Also, make sure the connections are clean and tight when you put the relay in place.

AS far as the IAC and the MAF, neither one would cause the fuel pump not to work. Something tells me you either have a bad relay, connection, or the pump is going bad.

Let me know about the relay.

Joe
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Wednesday, May 20th, 2020 AT 1:05 PM (Merged)
Tiny
KIRBYMURPHY
  • MEMBER
  • 7 POSTS
Already swapped in the AC clutch relay as a check and there is a new relay in place.
Engine started after I temporarily replaced the relay with the AC clutch relay, so I went ahead and bought a new relay.

Looks like it is something else and the starting was a coincidence. :(

Checked the collision switch and it's reset.

I suppose it "could" be the pump, but I would expect it to work or have total failure.

I'm looking for things that would cause the relay not to energize the pump before I undertake a tank drop and pump replacement.

Thanks!

EDIT"
Looks like the pump relay + side is in series with the PCM relay, so if the PCM relay isn't closed the pump relay gets no power.
The ground side of the pump relay is connected through the PCM module.


https://www.2carpros.com/forum/automotive_pictures/458250_pump_1.jpg

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Wednesday, May 20th, 2020 AT 1:05 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Let me know what you find.
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Wednesday, May 20th, 2020 AT 1:05 PM (Merged)
Tiny
KIRBYMURPHY
  • MEMBER
  • 7 POSTS
Yesterday I swapped in a new PCM relay in the relay/fuse box. Car started right up and I thought it was fixed.

10 degrees. It failed at the grocery store this morning.

I knew when I didn't hear the pump when I turned on the key that there was a problem, and of course it didn't start. Sat there for about 15 minutes, trying it every couple of minutes. Then I heard the pump and it fired right up.

Summary
If the pump won't run, it won't start. (Obviously)
When it does start, the pump never fails to run. Never shuts off while driving.
While I can't say for sure, I think the pump is fine based upon those observations.

Guess next I'll meter at the inertia switch and make sure there is power back to it. If there is, the pump (or wiring harness) must be bad. If not, it must be ahead of the inertia switch.

I'm leaning to the PCM or a sensor that sends a needed command to it. I wish I knew what sensor could send or not send the needed signal to the PCM. Anyone know where I can find a diagram of the wiring to the PCM and sensors? Maybe I'll unplug/plug-in the connectors on the relay box and PCM
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Wednesday, May 20th, 2020 AT 1:05 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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From what I remember, the inertia switch will also shut down the power to the ignition. Do you have spark when this happens?
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Wednesday, May 20th, 2020 AT 1:05 PM (Merged)
Tiny
TODDL
  • MEMBER
  • 1 POST
  • 1994 FORD TAURUS
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 190,000 MILES
II have the 1994 ford taurus sho with 3.2 liter in it just up and died going down the road. I checked the fuel pump but theres no pwer going to it, I bought a relay but im unable to lcate can you plz help find it, or if that is even the problem why have no power to my fuel pump. Thank you for your time
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Wednesday, May 20th, 2020 AT 1:05 PM (Merged)
Tiny
KIRBYMURPHY
  • MEMBER
  • 7 POSTS
If you look at the schematic above you can see that the "Pinto" intertia switch cuts power to the pump. It doersn't show up in the ignition circuit, and in fact has just 2 wires, one in and one out of the switch. One from the relay and one to the motor. I even jumpered it out for testing.

Problem is, it hasn't failed since yesterday morning so further testing is moot. God and bad I suppose. :()
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Wednesday, May 20th, 2020 AT 1:05 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
It's in the constant control relay module, under the hood. You might also take a look at the inertia switch.


https://www.2carpros.com/forum/automotive_pictures/170934_ford_taurus_show_1.jpg

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Wednesday, May 20th, 2020 AT 1:05 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
I looked at the schematic and see what you mean. Do you still have it bypassed?
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Wednesday, May 20th, 2020 AT 1:05 PM (Merged)
Tiny
KIRBYMURPHY
  • MEMBER
  • 7 POSTS
No. But it had failed while bypassed.
2 days later, no failure, so no chance to troubleshoot.

My gut tells me it's in the relay panel assembly or another relay. When I had my wife switch the key to ON, there would be no pump sound. When I swapped the relays around again, and had her try, I heard the pump and told her to try and start it. It fired right up.

The relay panel was the only area I was moving things around and presumably the only place to have any physical movement. Maybe it spontaneously decided to work, or maybe my removing and swapping relays caused an intermittent connection to make the proper contact.

I'm going to buy another new relay so BOTH the Fuel Pump relay and the PCM relay are new. Right now the AC Clutch relay is in one of the slots.

I'd like to yank the entire relay panel and check the connections but it's 5 degrees and it looks like a lot of labor. :) Anyone ever pull the assembly?

Of course I can't rule out the PCM itself. It is an odd setup the way the PCM completes the ground for the Fuel Pump relay on the LB/O wire.

Thanks.
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Wednesday, May 20th, 2020 AT 1:05 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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The relay does seem to be the only thing that has made the change. And, I don't blame you for not working on it with that temp. It could be something as simple as a loose connection in the relay block.

Regardless, let me know what you find.
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Wednesday, May 20th, 2020 AT 1:05 PM (Merged)
Tiny
KIRBYMURPHY
  • MEMBER
  • 7 POSTS
No start yesterday morning.
No pump, no start.

Semi-permanently bypassed intertia switch. While the wires were apart and not connected to the pump, I only measured 6.8 volts on the DG/Y wire from the Fuel Pump relay.

The only path is through the Fuel Pumo relay, through the PCM relay and direct to the 30A fuse link. Guess I need to find that fuse link and work my way back to the pump.

The relay panel looks like a bugger to get out and apart.

The perplexing thing is that it runs fine after starting. Makes me wonder about that little diode right after the 10A fuse in the start portion of the scematic. It's the only thing not in the circuit during run condition. Maybe it's gone high resistance and won't fully pull-in the PCM relay, dropping my voltage to 6.8v.
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Wednesday, May 20th, 2020 AT 1:05 PM (Merged)
Tiny
DBOY13PR
  • MEMBER
  • 1 POST
  • 1993 FORD TAURUS
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 89,000 MILES
Im having a fuel pump that stays on when I turn on the egnition and fan stays on too, the car wont start, can anybody please help me with my problem?

I have a new fuel pump and new throttle positioning sensor, I can not find fuel pump relay. Can any one help?
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Wednesday, May 20th, 2020 AT 1:05 PM (Merged)
Tiny
AMRAAM35
  • MEMBER
  • 39 POSTS
When your ignition is on, your fuel pump should be on and stay on, until your ignition turns off. So should the fan. If you are refering to the pump staying on after you turn the car off, it could be the relay, but also check the power line to the relay, it may be getting a signal to stay on. The relay is in the fuse box, usually the engine box.
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Wednesday, May 20th, 2020 AT 1:05 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
I was wondering if you have had the chance to check things out and what you found.

Joe
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Wednesday, May 20th, 2020 AT 1:05 PM (Merged)

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