When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I drove home while it was raining, the next evening i went to start it and it did not make the fuel pump sound so i tried to start it anyhow, it would not start.. the Question is, is it the fuel pump or the fuel pump relay? Previously for about a month i would hear a humming noise from the rear of the car
Last edited by rob420; Nov 16, 2025 at 09:24 AM.
Reason: change title
I drove home ... the next evening ... it did not make the fuel pump sound... it would not start... is it the fuel pump or the fuel pump relay?
Could be either.
I would start with Fuse 2 then check for 12v at the relay and then at the fuel pump. I thought there's a spec for the fuel pump windings, but it appears to be a "it either runs or doesn't" spec.
ETM 23-1 L4 Fuel System 11-122 Main Relay Testing
If you want to, you can test the Main Relay. I just keep a tested and verified as working Main Relay to be used to swap in for a quick "test", then it goes back into the tester box.
I say "if you want to" test the Main Relay, from my own experience: the culprit is never the main relay for me. It could be for you, so let us know what you find!
Previously for about a month i would hear a humming noise from the rear of the car. im still trying to find out where the relay switch is located
The fuel pump running can sound like a humming.
The relay switch is under the dash, as you can see above in the power distribution the pump is on when the ECU calls for it. As you know, when the key goes to position 3 before START, the ECU calls on the pump while the dash runs the bulb test. If you aren't getting 12v at the fuel pump during bulb test then you can go hunt for the Main Relay (on the driver's side above the fuse block).
You would be looking for this: PGM-Fi Honda Main Relay
Again, it would be surprising to me if this was the root cause BUT if it is I would love for you to open the old one and post close pictures of the inside so we can see the mode of failure.
The relay switch is under the dash, as you can see above in the power distribution the pump is on when the ECU calls for it. As you know, when the key goes to position 3 before START, the ECU calls on the pump while the dash runs the bulb test. If you aren't getting 12v at the fuel pump during bulb test then you can go hunt for the Main Relay (on the driver's side above the fuse block).
You would be looking for this: PGM-Fi Honda Main Relay
Again, it would be surprising to me if this was the root cause BUT if it is I would love for you to open the old one and post close pictures of the inside so we can see the mode of failure.
i went and got a fuel pump, i'll attempt to install it soon...maybe tomorrow.. thanks for your input.
from my experience, another way to check if it's the main relay is to see that the check engine light would go on at ignition-ON position then extinguish within 1-2 seconds before cranking.
if it stays solid and on at ign-ON, then the relay is likely stuck open and not allowing the pump to run.
fuel pump
