Fuel pump fuse keeps blowing.

[Chicagotrader92]

Okay. 

so, I just replaced my entire suspension and installed coilovers. Took it around the block a few times, then it died. I found the fuel pump fuse blown. So I swap it. Started right back up. Idled for 5 minutes. Died again. 

swapped the fuel pump relay with a spare I had and did a new fuse again. Drove around the block. Died. 

I’ll order another fuel pump relay and main relay again to make sure that’s not that, but I’m pretty confidence it’s not. 

but what else could be going on here? I really think all the suspension work is a coincidence. 

* EDIT: It seems to be dying faster and faster. First 4 blocks, then three, then two, then one. Tried inching it back to my house, but now it will only idle for 15 seconds before blowing a fuse.

^ This makes me think it's a bad fuel pump. Reason being is what else could have gotten progressively worse so quickly? I did the single in-tank fuel pump mod 1 year ago to remedy a hot starting issue. Its been great ever since today. 

thanks. 
 

[Galahad]

how old are your fuel pump and filter?

[Chicagotrader92]

how old are your fuel pump and filter?

I did the single in-tank fuel pump mod about 1 year ago. I’m opening up the fuel tank now to see if something’s up with it. 

[stuartinmn]

If the problem just started after you worked on the suspension, it may be related to something you did.  Are there any pinched wires, or maybe one that had its insulation scraped so there's bare copper that could be intermittently touching?

[Chicagotrader92]

If the problem just started after you worked on the suspension, it may be related to something you did.  Are there any pinched wires, or maybe one that had its insulation scraped so there's bare copper that could be intermittently touching?

I'll double-check. I have the Angry-Ass solutions brake wear sensor deletes, and I can't imagine a wheel speed or ABS wire creating a fueling issue. But I guess anything is possible. Sucks i have to do this on a random side street. I will say I had a very intermittent, long crank hot start issue once every 100 start-ups. This leads me back to a bad (aftermarket) in-tank fuel pump. 

* Also, the old fuel pump wiring was never fully secured... I'll double-check that there are no contacts going on there. 

[4DSC]

To add on to what's been posted, I feel like there are a couple possibilities:
- There's an electrical short somewhere, possibly introduced by something you did during the suspension work
- There is a restriction somewhere in the fuel system that is causing the pump to work very hard and over-draw current
- The pump itself just went bad internally causing a current spike.

You could try approaching it "scientifically" if you have a fuel pressure gauge and/or a way to measure current draw. I think if the pressure is normal always it's likely a short. If there's an obstruction somewhere (fuel filter or otherwise) I feel like you'd probably see lower pressure and maybe progressively higher current draw as the pump has to work harder and harder until the fuse pops. If pressure is normal and there's just an abrupt spike in current draw, wiring short or bad pump. If the fuse doesn't pop at all when the car isn't moving, possibly suggests wiring short that only gets triggered when things move around and two wires touch while the car is in motion.

[Chicagotrader92]

To add on to what's been posted, I feel like there are a couple possibilities:
- There's an electrical short somewhere, possibly introduced by something you did during the suspension work
- There is a restriction somewhere in the fuel system that is causing the pump to work very hard and over-draw current
- The pump itself just went bad internally causing a current spike.

You could try approaching it "scientifically" if you have a fuel pressure gauge and/or a way to measure current draw. I think if the pressure is normal always it's likely a short. If there's an obstruction somewhere (fuel filter or otherwise) I feel like you'd probably see lower pressure and maybe progressively higher current draw as the pump has to work harder and harder until the fuse pops. If pressure is normal and there's just an abrupt spike in current draw, wiring short or bad pump. If the fuse doesn't pop at all when the car isn't moving, possibly suggests wiring short that only gets triggered when things move around and two wires touch while the car is in motion.

So slight update. 

1) I crawled underneath the car and found one of the old fuel pump wires sitting on top of the rear subframe. Although I do not think this is the issue, it wasn't very exposed and the insulation on it is pretty thick. I wrapped it in electrical tape and got it out of the way. (When you do the single in-tank fuel pump conversion, the old wires and rendered useless). I really do not think any of the ABS/wheel speed sensor wires would be able to cause a fuel pump short. 

2) I took out my single in-tank fuel pump and inspected the soldering and ground connection. The solder looked good, but the ground connection was meh, so I redid that as well. 

* I re-installed it, went to crank it, and.... No start. Just long crank. 

* This leads me to believe the TRE fuel pump is faulty. I overnighted a cheap (temporary) replacement fuel pump from Amazon. I just want it off the street and in my garage. If the fuel pump doesn't fix it, I might fork up the cash and bring it to whatever respectable shop I can find in Chicagoland. 

* I do worry that this could be the start of a bad fuse box? I plan on doing the Holy Grail upgrade, but not trying to do that on a side street far from my house. 

* Bad ECU? 

[Mike W.]

* I do worry that this could be the start of a bad fuse box? I plan on doing the Holy Grail upgrade, but not trying to do that on a side street far from my house. 

* Bad ECU? [/justify]

Very, very doubtful it's the fusebox, and an easy no on the ECU. It's the wiring. Have you checked it with a meter yet? Do that. Not sure how you've got it wired, but disconnect the pump at the fuel tank. Ohm it out, the pump. You should get a low reading, but not zero or less than an ohm or something. That means a dead short, which is what it sounds like you have. So, actually I'd kind of expect that. You can also pull the fuse and ohm it out from the body side. I'm not sure what else is on that circuit, but it, again, should not be a dead short.

[Chicagotrader92]

Potentially solved: was able to get the car home without any issues, about 1 mile. 

* I replaced my single in-tank fuel pump. Instead of re-soldering the power to the connector up top (and grounding to the internal support / housing thingy), I drilled a new hole up top and ran 16 gauge wire to the old external fuel pump electrical (next to the fuel filter). Surprised more people don’t do this rather than soldering the in-tank pump to the connector up top. 

I’m not sure if the previous TRE fuel pump went bad and caused the issue, or if a short somewhere within the connector harness caused the issue + and the TRE fuel pump to go bad. I checked under the rear seat and all the wiring was perfectly original untouched. 

It’s not a perfect job yet, the new Quantum Fuel System fuel pump is about 1/4inch too tall and does not allow a perfect seal on top of the tank. I’ll worry about that next week. TRE is out of the pump I need for another month, and the QFS one seems to be decent quality with a “warranty.”