Strange issue - Aux fuel pump won't stop running
09-04-2014, 02:43 PM
#1
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Strange issue - Aux fuel pump won't stop running
This all started about two days ago on my silver 98 daily driver sc'd Max. I pulled out of my dwy and pulled over 100yds away to stop and get my mail. As I got out of the Max, I smelled a really strong smell of gas. I popped the hood but couldn't see any visible leaks. I dismissed it and drove away.
Yesterday I'm washing the Max. Out of nowhere, this loud whizzing noise starts under the hood! What the heck?! I pop the hood, and to my surprise, the auxiliary fuel pump is running with the car off. How is this possible? I start and stop the car, same thing, aux fuel pump keeps running. I had to disconnect the battery.
FWIW, it's installed exactly as Stillen suggested. Been trouble free for a year+ now. See attached picture.
So, I'm thinking it could be any of the following:
1. A short in one of the wires (probably the yellow wire that runs into the cabin)
2. Bad aux relay Stillen provided
3. Bad pressure switch Stillen provided
4. Bad OEM relay that the yellow wire connects to
Any other possibilities? Any other suggestions before I dive into troubleshooting? Thanks in advance.
Yesterday I'm washing the Max. Out of nowhere, this loud whizzing noise starts under the hood! What the heck?! I pop the hood, and to my surprise, the auxiliary fuel pump is running with the car off. How is this possible? I start and stop the car, same thing, aux fuel pump keeps running. I had to disconnect the battery.
FWIW, it's installed exactly as Stillen suggested. Been trouble free for a year+ now. See attached picture.
So, I'm thinking it could be any of the following:
1. A short in one of the wires (probably the yellow wire that runs into the cabin)
2. Bad aux relay Stillen provided
3. Bad pressure switch Stillen provided
4. Bad OEM relay that the yellow wire connects to
Any other possibilities? Any other suggestions before I dive into troubleshooting? Thanks in advance.
10-15-2014, 10:38 PM
#6
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Well, I dove into troubleshooting today and the aux fuel pump relay was dead. Swapped it out for another one.
Hard to explain, but I have the relay tucked behind that small rectangular fuse box near the driver headlight. I figured it had something to do with washing the car, because the aux fuel pump turned on as I was washing it. I imagine some water got on the connections and shorted it as it's directly below the hood's water channel. I bet the water channel overflowed a little, and onto the relay it went. Time to relocate the relay or heat shrink tube it with some waterproof abilities.
On a side note, I also determined that the MEVI is no longer activating like it used to. I tested that relay and it was ok. So either the vacuum solenoid took a dump or the Harlan switch did. I'll troubleshoot this next week. If the Harlan died, then I'm just going to ditch all this archaic stuff and either install a VAFCII or an EU and control it that way, as well as having the ability to tune. Probably will go with the EU so I can tune properly, raise the rev limiter, and benefit from the nice 2-step launch.
Hard to explain, but I have the relay tucked behind that small rectangular fuse box near the driver headlight. I figured it had something to do with washing the car, because the aux fuel pump turned on as I was washing it. I imagine some water got on the connections and shorted it as it's directly below the hood's water channel. I bet the water channel overflowed a little, and onto the relay it went. Time to relocate the relay or heat shrink tube it with some waterproof abilities.
On a side note, I also determined that the MEVI is no longer activating like it used to. I tested that relay and it was ok. So either the vacuum solenoid took a dump or the Harlan switch did. I'll troubleshoot this next week. If the Harlan died, then I'm just going to ditch all this archaic stuff and either install a VAFCII or an EU and control it that way, as well as having the ability to tune. Probably will go with the EU so I can tune properly, raise the rev limiter, and benefit from the nice 2-step launch.
10-16-2014, 07:29 PM
#9
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Join Date: Feb 2013
Posts: 218
Yeah, take a small air pressure regulator, and plumb it to the pressure port. hook your volt meter to it and set it on OHM's. It will be open, adjust the regulator to whatever lbs you want the pump to activate at and adjust the Allen screw the Hobbs accordingly. Do them both the same. Wire them both in parallel so that if one fails, the other activates the system. I've run many setups this way, not 1 problem.
10-18-2014, 06:23 PM
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^Thanks for the info.
Well, I figured out why the MEVI wasn't activating properly. The vacuum solenoid took a dump. I tested it and it failed. Harlan tested out just fine. Installed a new vacuum solenoid and I'm back in business.
I bought a 5th gen clock. I plan to hook up a signal wire to a 5th gen clock which has the security LED and have it turn on when the MEVI activates. This way, I have a quick way of knowing that the MEVI is activating from inside the car. Only God knows how long I've been driving around with my MEVI like this.
credit goes to Jsutter
https://maxima.org/forums/4th-genera...ift-light.html
Well, I figured out why the MEVI wasn't activating properly. The vacuum solenoid took a dump. I tested it and it failed. Harlan tested out just fine. Installed a new vacuum solenoid and I'm back in business.
I bought a 5th gen clock. I plan to hook up a signal wire to a 5th gen clock which has the security LED and have it turn on when the MEVI activates. This way, I have a quick way of knowing that the MEVI is activating from inside the car. Only God knows how long I've been driving around with my MEVI like this.
credit goes to Jsutter
https://maxima.org/forums/4th-genera...ift-light.html
10-19-2014, 01:19 PM
#12
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Join Date: Feb 2013
Posts: 218
You can drill a 1/16 hole in the gauge pod that holds the boost gauge. Install a small LED light wired to the signal wire, when the wire excites, the LED lights. Easy cheasy. That is what I suggest on water kits, as you will know when the meth is spraying. Looks like you got a handle on it. Good lucks.
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