Hey guys, first time posting a new thread on here so let me know if it is in the wrong section or if there is a thread out there that answers me questions or will help me figure out my issue.

I have a modded 94 RX7 with a single Aeromotive 340 stealth fuel pump. A couple of months ago, I lost all power to my fuel pump. Figured out the fuse had blown under the drivers side fuse panel for the fuel pump. replaced the fuse and made it about 4 miles and the fuse blew again. I towed the car home and finally just ran a wire straight from the battery to the fuel pump with a toggle switch, an inline relay, and 20 amp fuse so that way I could keep and going if the fuel pump fuse blew while driving. I was able drive around a hundred miles without an issue from the main fuel pump fuse but finally it blew again and the toggle switch method got me back home. I replaced the main fuel pump fuse and the car wouldn't start. I flipped on the hot wire and the inline fuse blew. If I touch just a hot wire from the battery to the fuel pump the fuel pump kicks on but the car only runs for a minute or two before it dies.

I have tried to do some research on the forums and try and diagnose the issue but I don't know enough about wiring and fuses and relays to even know where to start. I was going to buy the fuel pump relay that sits in front of the radiator but its almost $90 bucks and I have read that the fuse only controls the low and high output for the fuel pump. I need to know if my problems could be from a relay or fuse that I have not located, if it is a wire grounding somewhere and if so, where to I even look. I considered doing the dale clark fuel pump rewire but I am afraid that if I go that route, I will still have the same issue. Also, could it be a fuel filter issue?

If anyone can steer me in the right direction on where to start looking and what could be the most likely cause, i would greatly appreciate the help.

 

Sounds like a wiring issue. A chafed wire that is grounding out will cause the fuse to pop. Make sure you have a GOOD ground in your circuit. When you re wired it, did you wire all the way to the pump? Or just to the connector? Check for chafing wires past what you've done as well as at your bulkhead pass through. Check the continuity of the wires you're using.

 

When I did the rewire, it was just to the connector. When i bought the car, it had a large external pump and surge tank and that is where the external pump was tied into for power. I started to look for any obvious wiring that was in bad shape but I didn't dig too deep yet. I have the workshop manual but I'm still trying to decipher the wiring diagram. If the fuel pump fuse is blowing, would that mean that any wire issue would be from that fuse panel back, so cockpit and hatch area?

 

Trace all wiring to and from the fuse. Is your car lowered? I've heard of chafing harnesses in the fender wells. A multimeter is going to be your friend here.

Matt

 

Check your normal current draw by putting the amp meter section of a multimeter that goes up to 20 amps DC in series with the pump, 20 amps at 13 Volts is a lot of power, so it sounds like an intermittent problem with wiring, but coiuld be a defective pump too. You can also check with the pump mfg what the normal power draw is supposed to be. If it happens again check to see if the wire is hot as close to the gas tank as you can get. If it's hot there then the pump is bad or your problem is in wiring at the connector or in the tank, If it's shorting out on the chassis somewhere in front of the tank then the section of wire going into the tank would not be hot.