Fuel pump relay location?

Tiny
PGRAVCO
  • MEMBER
  • 1998 HONDA PRELUDE
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 146,000 MILES
1998 Honda prelude - fuel pump at the connector is not getting power. Directly powered the pump it turned on.
new main relay installed, fuse is ok.
please let me know what I should do next.
Thanks
ignition switch was replaced 7 months ago due to the recall on these models.

is there any other component that would cut off power to fuel pump such as ignition switch, coil, or ECU or anything else.
i tried to trace wires from along the passenger door to the foot rest in the passenger compartment that is where the ECU and first connection is
Friday, May 13th, 2011 AT 6:36 PM

23 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
The black and yellow wire from the PGM-FI main relay going to the fuel pump is open. Dunno if you direct both power and ground from the battery -also check ground circuit see below if all okay here-think! Computer

Check fuse no.2 and 4 in underdash fuse/relay box-
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Friday, June 24th, 2011 AT 7:59 AM
Tiny
GOLDPAN
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  • 1 POST
  • 1992 HONDA PRELUDE
  • 4 CYL
  • 2WD
  • MANUAL
  • 15,000 MILES
Where is the fuel pump relay
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Monday, January 4th, 2021 AT 8:52 AM (Merged)
Tiny
RASMATAZ
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The PGM-FI main relay powers the fuel pump relay. Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.
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Monday, January 4th, 2021 AT 8:52 AM (Merged)
Tiny
ELEMENT13
  • MEMBER
  • 4 POSTS
  • 1993 HONDA PRELUDE
  • 4 CYL
  • 2WD
  • MANUAL
  • 198,000 MILES
93 Prelude Vtec sat for 5 months in hot Vegas weather & won't start now. I checked distributor & it meets all voltage to spec + I get spark at all plugs. Pulled fuel pump & connected it to 12volts it was locked up. Bought & tested new fuel pump with 12 volts and it runs fine. Installed new fuel pump and it won't turn on. Jumped black/yellow wires at fuel main relay & tested for continuity = new pump passed continuity test. Removed fuel shut off main relay, re-soldered all board connections & reinstalled. Visually inspected all fuses. The fuel pump still won't start.

Any thoughts?

Thanks,

Justin
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Monday, January 4th, 2021 AT 8:53 AM (Merged)
Tiny
KHLOW2008
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Hi Justin,

Did fuel pump run when power was applied to Yellow/Green wire?
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Monday, January 4th, 2021 AT 8:53 AM (Merged)
Tiny
ELEMENT13
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  • 4 POSTS
The fuel pump was not grounding properly. I properly ground the fuel pump and it works as it should.

Thanks all the same.

Justin
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Monday, January 4th, 2021 AT 8:53 AM (Merged)
Tiny
KHLOW2008
  • MECHANIC
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Hi Justin,

That was what I suspected ;)

Cheers. :)
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Monday, January 4th, 2021 AT 8:53 AM (Merged)
Tiny
METSFAN69
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  • 2 POSTS
  • 1992 HONDA PRELUDE
  • 4 CYL
  • FWD
  • MANUAL
  • 14,900 MILES
My question is simple, how difficult would it be for me to aquire/change the fuel pump relay on my 1992 honda prelude?
the reason i ask is because i took her to a mechanic i've used in the past and he quoted me right at $200 and i think he might be full of $#! .
I've attached a picture of what i think the fuel pump relay looks and its only $50 online.
Basically, what i need to know is do i have the right part in mind and can i replace it myself?

thank you


http://www.2carpros.com/forum/automotive_pictures/234178_getimagephp_3.jpg

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Monday, January 4th, 2021 AT 8:53 AM (Merged)
Tiny
RASMATAZ
  • MECHANIC
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The PGM-FI main relay also powers the fuel pump located behind left side of dash above clutch pedal bracket.


https://www.2carpros.com/forum/automotive_pictures/12900_pgmfi_relay_1.jpg




https://www.2carpros.com/forum/automotive_pictures/12900_pgmfi_wiring_1.jpg

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Monday, January 4th, 2021 AT 8:53 AM (Merged)
Tiny
JASON CARSON
  • MEMBER
  • 2 POSTS
  • 1992 HONDA PRELUDE
  • 4 CYL
  • FWD
  • MANUAL
  • 235,000 MILES
I have spark but no fuel. I didn't hear the fuel pump kick on when I turn the key, so I pulled the access panel inthe trunk floor to check for power to the pump. My understanding was that if I had power to the pump, when I turned it over, then one of those wires should light my test light for a few seconds and then go out. But I tested all 5 wires and 2 green wires had power anytime the key was on but didn't shut off after a few seconds. The other three were white and did not light the tester. My first question is there a relay switch or a fusable link somewhere that I can check, and if so where the heck is it. I lost the manual! Also when this happened it happened all at once. I had just got done putting an oil pan on it and when I was done I started the car to see if it was leaking and then shut it off then I tryed to start it to pull it out of the garage and it wouldn't start so when I saw the gas gauge said empty I thought that was why it wouldn't start so I went and got gas and it still wouldn't start do you think there is any connection. Or is it something electrical any help is greatly appreciated and i'm sorry I have nothing to donate but this car is nickle and diming me to death thanx jason
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Monday, January 4th, 2021 AT 8:53 AM (Merged)
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS


https://www.2carpros.com/forum/automotive_pictures/62217_Fuel_Pump_Relaya_1.jpg



https://www.2carpros.com/forum/automotive_pictures/62217_Fuel_Pump_Relay_1.jpg

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Monday, January 4th, 2021 AT 8:53 AM (Merged)
Tiny
KHLOW2008
  • MECHANIC
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Hi jason carson,

The relay is located underdash above driver left leg. See pix by merlin2021.

Take it out and resolder the circuit board, it would save you time, money and many headaches later on.

.
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Monday, January 4th, 2021 AT 8:53 AM (Merged)
Tiny
MERLIN2021
  • MECHANIC
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KHlow2008 We do survive by donations, so don't encourage otherwise, please!
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Monday, January 4th, 2021 AT 8:53 AM (Merged)
Tiny
KEN L
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We help as much as we can with what you can give if nothing we will try to help. But the money does keep things going, kind of a catch 22.
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Monday, January 4th, 2021 AT 8:53 AM (Merged)
Tiny
FGB56
  • MEMBER
  • 4 POSTS
  • 1986 HONDA PRELUDE
I have a 1986 Honda Prelude 1.8L Carbureted Manual Trans. I'm only getting 2.7 volts to the fuel pump through the wire harness with the cut off relay in. When I try to by-pass the relay to test the fuel pump I get 0 volts with the ignition switch in the on
position. What could it be?
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Monday, January 4th, 2021 AT 8:53 AM (Merged)
Tiny
RASMATAZ
  • MECHANIC
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Power the fuel pump direct from the battery and see if it'll come on. If it does best test the main relay thoroughly-could be the injectors shorted out dragging down the voltage they tied in together to include all the solenoids-
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Monday, January 4th, 2021 AT 8:53 AM (Merged)
Tiny
FGB56
  • MEMBER
  • 4 POSTS
The fuel pump powers on with 12 volts applied directly to it. This is a carbureted engine 2 carb 1.8L. No main relay just a fuel cut-off relay that tested good. What else do you think it could be? The ignition module is new and I have a good spark also, pump is just not turning on when it's plugged into the harness. Can't even hear it turn on. Really low voltage like 2.7 all the grounds are good. I have 12 volts at the fuse block. The pump doesn't have a fuse just the relay between it and the fuse block.
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Monday, January 4th, 2021 AT 8:53 AM (Merged)
Tiny
RASMATAZ
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Sounds like a problem with the ignition switch-check the ignition coil if you have battery voltage on the pos. term.

See diagram


https://www.2carpros.com/forum/automotive_pictures/12900_fp_68.jpg

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Monday, January 4th, 2021 AT 8:53 AM (Merged)
Tiny
FGB56
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  • 4 POSTS
Thanks I'll do that. Also when I measured the coil primary it was 1.9 ohms. The values should be 1.07 to 1.6 ohms so it's out of range slightly. The secondary is 9,300 ohms, the range should be 7,000 to 11,000 ohms. Could a bad ignition coil primary cause the pump not to turn on too by dragging the voltage down? I'm trying to understand this from an electronic perspective.
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Monday, January 4th, 2021 AT 8:53 AM (Merged)
Tiny
FGB56
  • MEMBER
  • 4 POSTS
I checked the voltage on the + side of the ignition coil and it's 12 volts (battery voltage). Do you have a wiring diagram of the ignition coil, where ALL the wires go. There is a blue wire, a black/yellow wire and a black wire from the distributor harness. Could this possibly be the problem, the wiring of the coil? Right now the blue wire is on the - negative terminal, the black/yellow is on the + terminal, There is a brown wire from the switch harness going to the - terminal on the coil also. There is a larger black /yellow wire going to the switch harness that is on the - terminal. A gray ground to the body from the switch harness and two blue wires that go to a harness on the - terminal. The black wire from distributor harness is a bullet connector that plugs into a black/red wire on the harness. I'm going to check all the grounds and see if I have continuity.
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Monday, January 4th, 2021 AT 8:53 AM (Merged)

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