Weird fuel pump issue, no switches 12v after OEM relay.
02-27-2019, 02:45 PM
#1
Registered User
Thread Starter
Weird fuel pump issue, no switches 12v after OEM relay.
Ok I’ve been messing with this for days now and am at al complete loss.
just finished up my turbo and the last item was to re-wire and install my Walbro 255.
installed SOS rewire kit and everything went great and is text-book.
Go to check power in the circuit and nothing, no 12v switch power from the OEM YLW/GRN wire.
ive went through the OEM manual and every trouble shooting item passes. I have power all the way to the Fuel pump relay under the dash. That relay is switching on, confirmed on my bench, even swapped in a new unit.
When I pull C-401 I get no power from the YLW/GRN coming from the under dash relay. So I though to check continuity between C-401 and the relay, all good.
Continuity from C-401 to the fuel pump is ok.
So all in all it has nothing to do with the SOS install because I’m not getting power from the under dash relay to C-401.
The manual says to check the power from the ECU (within the first two seconds of key) but it says I need the HDS for that. I don’t see how the ECU could have fried from moving the OEM 12v fuel pump terminal 12”.
Can anyone maybe see something im missing? I’m supposed to start tuning very soon.
just finished up my turbo and the last item was to re-wire and install my Walbro 255.
installed SOS rewire kit and everything went great and is text-book.
Go to check power in the circuit and nothing, no 12v switch power from the OEM YLW/GRN wire.
ive went through the OEM manual and every trouble shooting item passes. I have power all the way to the Fuel pump relay under the dash. That relay is switching on, confirmed on my bench, even swapped in a new unit.
When I pull C-401 I get no power from the YLW/GRN coming from the under dash relay. So I though to check continuity between C-401 and the relay, all good.
Continuity from C-401 to the fuel pump is ok.
So all in all it has nothing to do with the SOS install because I’m not getting power from the under dash relay to C-401.
The manual says to check the power from the ECU (within the first two seconds of key) but it says I need the HDS for that. I don’t see how the ECU could have fried from moving the OEM 12v fuel pump terminal 12”.
Can anyone maybe see something im missing? I’m supposed to start tuning very soon.
02-27-2019, 10:07 PM
#3
Fuel pump fuse good? Did you check all fuses attributed to that circuit? I'm not sure if this one matters but do you have good grounding on your hardwire? I think I saw your post on FB. Did you physically verify with a DMM lack of 12v switched with key on @ the oem power wires by attaching alligator clips to the bare terminals without them being plugged into the relay socket? I really don't think your ECU is the problem. Given your attention to detail in your build thread I'm sure your install was meticulous, but I highly doubt you could've fried anything. Do you have a good crimp on the new terminals that you've attached to the oem power wires? Like I said, I'd de-pin them and check them directly off of the terminals. If no dice there I'd go one step further and use probes on the bare wire strands. Also check for continuity to ground on those wires to check for a short, and if you can, get yourself a length of wire, and check for continuity from the ECU plug all the way back to both wires at the pump to ensure there isn't a break anywhere.
Not trying to insult your intelligence as you said you went through the manual. I'm sure you've made some good verifications but with stuff like this the issue is usually even simpler than what you're looking for....I tend to look into things way too deeply, and end up finding my issue by starting from the absolute bottom/basics when it comes to electrical.
Not trying to insult your intelligence as you said you went through the manual. I'm sure you've made some good verifications but with stuff like this the issue is usually even simpler than what you're looking for....I tend to look into things way too deeply, and end up finding my issue by starting from the absolute bottom/basics when it comes to electrical.
02-28-2019, 10:20 AM
#4
Registered User
Thread Starter
Update: Got a spare ECU and my buddy at my local Honda did the update, car fired right up, I don’t understand how that ECU went bad. Then I notice another problem, no fuel level. After smashing my head against the wall I pulled the assembly back out. I’m only getting 6.5V at the sensor, and zero continuity across the sensor. My question is should the sensor see 12v? I can’t find that data in my manual.
And I agree with you it’s usually simple.
And I agree with you it’s usually simple.
Last edited by Nfinitecc; 02-28-2019 at 12:08 PM.
02-28-2019, 11:59 AM
#5
I'm not totally clear on what your describing with the level sensor - fuel level readout on dash not showing I assume? If so, I know with my recent issue, I had to re set the ecu/pull batt terminal to get the fuel level bars on dash to register again after monkeying around with the fuel pump hanger. The ECU is tied to the level readout on the fuel pump hanger.
02-28-2019, 12:11 PM
#6
Registered User
Thread Starter
I'm not totally clear on what your describing with the level sensor - fuel level readout on dash not showing I assume? If so, I know with my recent issue, I had to re set the ecu/pull batt terminal to get the fuel level bars on dash to register again after monkeying around with the fuel pump hanger. The ECU is tied to the level readout on the fuel pump hanger.
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