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I was happy to have nice weather today and decided to drive my Special Edition Subaru converted Fiberfab Speedster the 15 miles to my business. I stopped at the top of my street to top my tank off, it took 4.3 gallons to fill to the bottom of the fill neck. I was happily motoring along about halfway to my destination when the engine died. There was no sputtering or warning just like it was turned off. I also noticed that my temp and fuel level combo gauge glass cover was fogged up from the inside which makes we worry that I have an electrical issue. I still have power to crank the engine over. I think the issue is with the electric fuel pump. You can usually hear it humming when you turn the ignition key on and now you can't. I removed the gas tank cap and turned the key on and can't see or hear the fuel as it returns to the tank either. Regardless, I wasn't going to be able to properly diagnose the car and repair it on the roadside. I called my friend who owns a local towing company. While I waited for the tow truck I was concerned with how we were going to get the car up on the roll back without damaging the car. The tow truck driver is a car guy and loved my car. He spent about 20 mins looking at the underside of my car and figuring out how to get it loaded safely. We had to enlist the use of 4 sections of 2 X 4 boards under the front and rear tires. We got the car loaded and back home in my garage to be looked at later today or this weekend. My Suby Speedster has been trouble free for 4500 miles. I fear the issue is electrical but hope it isn't. I will post what I find in the next few days.

Speedster being towed 1Speedster being towed 2Speedster being towed 4

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Original Post

Subaru fuel pumps need 12 volts to work.  Anything less and they simply on't operate.

If that's the problem, it could be a loose or weak ground, a faulty relay or a loose or weak joint in the wiring harness.

Try hard wiring the fuel pump to a good 12 volt source and see if starts humming.

I'm in the process of figuring out how to rewire my fuel pump for that very reason.

Last edited by Jethro

@ Jimmy V.    i concur...fuel pressure relay..similar to "blown fuse"....i saw that exact ROLL BACK scenario TWICE for exactly this same issue when first got my car....luckily "john boy" steele did warranty this with OUTFRONT subaru guys....just added more fuse power with updated wiring fix.....good luck with the remedy and please do let us SUBIE guys know what it was for future reference

I have filled the car up to this level many times but who knows I will check it out. I have also had a electrical issue with my horn circuit that started when I changed my steering wheel. The horn went off on it's own last week while driving and I pulled over and pulled one of the wires at the horn. I haven't made time to address the issue. I sure hope it hasn't caused some larger electrical problem. As I said, my combo gauge glass was fogged up and I think this is the result of something getting hot under the dash. 

Carey emailed me and told me about the only time he has seen the fuel pump my car has fail ( Walboro GSL392BX )  is after running the tank dry of fuel and subsequently sucking a bunch of crude into the pump. I just had happened to have run my tank bone dry the last time out and made it almost 10 miles in barely running mode to get to a gas station. I am sure this would have sucked up any and all crude in the bottom of my tank. I will still test the pump by running 12v power direct to it before I diagnose it as bad. I will report back when I can get time to work on it. 

Ah good luck Jimmy. Do yourself a favor and make sure it's the pump before replacing. If it's not running at all you've got it.

I neglected this step and as a consequence happen to have a spare good pump...

Also, Bridget died one time when the cat burned through an O2 sensor wire I'd negligently left unbound. Just cut off and would not restart. Found and fixed easily; lesson learned.

I had time today to look into the non-running fuel pump issue. I jacked the car up and removed the passenger side wheel. Carey has a Walboro high pressure fuel pump mounted on the pan directly below the fuel tank. I first checked for current to the pump. I turned the ignition key to the start position and this is where I would normally hear the faint hum of the pump. I hear nothing. I checked for 12v.current to the pump and have nothing. The 12v hot wire runs over to a junction with the radiator fan and thermostat switch. I am going to look for the fuse that is in line with the pump. It may be on the same circuit as the cooling fan. I hate wiring issues. I would rather have had a bad pump and that is it. I still may have a bad pump, I haven't checked it yet by running a separate 12v power source to it. More to come. 

 Who said a pan based car isn't strong or rigid enough. I have the front of the car jacked up under the axle next to the shock tower base. After the tire near the jack was off the ground a couple of inches the other front tire and the rear wheel on the jack side all came off the ground. I am able to open either door and they shut and latch smooth as silk so there is no body flex at all. That is better than many factory built convertibles I have owned. The pan attached correctly to the frame bonded to the glass body make for a super strong unit. At least it is in my car.

Speedster jacked

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I have an email in to Carey. I am stumped for now. I am getting zero voltage to the fuel pump and noticed a faint buzzing from the back of the car. I removed the rear seat cushion and exposed the ECU. The brown relay? box is buzzing when I turn the ignition to the start position. I did a scan with my scan gauge and it is showing a low voltage condition but I am getting 13.7 at the alternator post when the car isn't running of course. I am going to remove the drivers side rear wheel tomorrow and open the battery box and check the posts for tightness and corrosion. The battery is a small ATV battery in a custom made box mounted in the drivers side rear wheel well. My car was a challenge to convert to Subaru power. Carey said the ECU is very sensitive to voltage and if it is low will not work. Maybe I am not getting enough voltage to the ECU and it isn't telling the fuel pump to run? I am guessing now but I am curious to what the bussing means. I doubt it is anything good...

speedster ECU

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Last edited by Jimmy V.
@Jimmy V. posted:

I had time today to look into the non-running fuel pump issue. I jacked the car up and removed the passenger side wheel. Carey has a Walboro high pressure fuel pump mounted on the pan directly below the fuel tank. I first checked for current to the pump. I turned the ignition key to the start position and this is where I would normally hear the faint hum of the pump. I hear nothing. I checked for 12v.current to the pump and have nothing. The 12v hot wire runs over to a junction with the radiator fan and thermostat switch. I am going to look for the fuse that is in line with the pump. It may be on the same circuit as the cooling fan. I hate wiring issues. I would rather have had a bad pump and that is it. I still may have a bad pump, I haven't checked it yet by running a separate 12v power source to it. More to come. 

 Who said a pan based car isn't strong or rigid enough. I have the front of the car jacked up under the axle next to the shock tower base. After the tire near the jack was off the ground a couple of inches the other front tire and the rear wheel on the jack side all came off the ground. I am able to open either door and they shut and latch smooth as silk so there is no body flex at all. That is better than many factory built convertibles I have owned. The pan attached correctly to the frame bonded to the glass body make for a super strong unit. At least it is in my car.

Speedster jacked

@Jimmy V. Hopefully it’s just the pump. Probably good to check for a good place to install a tow hook. I was talking to my friend about this topic a few weeks ago to avoid damage. 

The new ignition relay came in and is doing the same thing as the old relay. It buzzes soon as the key is turned on. The fuel pump is good. I unhooked it and connected 12V power to it and it runs fine. I am not getting any current to the pump when the key is turned on. I called Carey again and it turns out That Mike will be driving within 20 miles of my house this weekend. Mike is going to stop by and look at my car on his way back from dropping a car off and I think picking one up on the way back. Mike will have another ECU and a fuel pump relay  with him, which Carey thinks is the real problem. All I can say is what amazing customer service. I am blown away and very appreciative. We have a real treasure in the Company called Special Edition! I really hope Mike can figure this out. I miss driving my Speedster.

I think you've got a short between the relay signal + and the relay power +.

I inadvertently wired a fan relay on Bridget this way once and that's what happened: buzz, no fan.

You'd think a 12v+ wire would be fine wherever it comes from but if the switch signal to the relay is somehow wired to the + FROM the relay to the component you get this weird feedback loop.

Trace the wires. Something is somehow shorted in a way that the fuse can't notice.

Thanks for the info. I agree with what you wrote. The week prior to this happening the horn went off and wouldn't stop until I pulled the power wire at the horn and I hadn't had time to look into why this happened. So something caused this as well. I also had a fogged up combo gauge when the car stopped running so I am not sure why this happened but think it was caused by some heated up wiring. The pump power runs from a connection block where the radiator fan and thermostat switch are attached. I checked this out but will do it better. Thanks again for your help Ed.

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