Fuel Pump Re-Wire Question.

[Mist3r Spool]

OK, I have the main parts required to rewire my fuel pump and am ready to go. I was thinking, instead of running the wire all the way from the battery in the engine bay, could I just run the power wire from the distribution block for my amps which is mounted in my trunk? I also have a 1-farad capacitor that ensures consistent power output of anything from that distribution block. Is this OK? It'll be a lot easier to run the wire. IMO, shorter wiring routes, especially for thinner wires, is usually better.

 

[Masochist]

Yes that will work. I would make sure you don't get noise in your audio system after you wire it that way though. Good luck

 

[Mist3r Spool]

Thanks for the response. Why would I get feedback in my audio system? I'm just using one of the many ports of my distribution block. If I split the audio system off the fuel pump wire, I could understand the noise but not in this case.

 

[ChvyKc]

I would be cautious doing that, even with a capacitor you still might have a voltage drop. Capacitors don't always garauntee constant voltage behind it. The only way to do that is with an auxillary batter, something like a yellow top Optima. It is something that you could try for sure, but I would try to test the voltage with a multi-meter to make sure that you are not getting a voltage drop. I did car audio work for two years and I am MECP certified and I have seen plenty of problems caused by that.

As far as shorter wire being better, that is not exactly the case. It is true to a certain extent, espeically when ground anything electrical, but not for feeding the fuel pump with enough voltage. As long as there is not a lot of resistance in the wire (which can really only be caused my corrosion or an butt load of connectors) then there should be no problem getting plenty of voltage to the fuel pump from the battery itself. I think that running it directly from the battery would be the best bet. That way you don't have to worry about other things pulling voltage from the fuel pump.

Just my two cents, you can try it from the distribution block, but I would keep a close eye on it for a while to make sure that it does work properly. Let me know how it works.

 

[ChvyKc]

Thanks for the response. Why would I get feedback in my audio system? I'm just using one of the many ports of my distribution block. If I split the audio system off the fuel pump wire, I could understand the noise but not in this case.

You shouldn't get noise from the fuel pump, it is possible but you shouldn't since the current is not actually running from it. Most of the time when someone has whine in their system, it is from the alternator and really can only be remedied by a noise filter either in the RCA's or in the power cable (I haven't seen one of those types in forever).

 

[Mist3r Spool]

Thank you for the technical response. I totally agree with you 100% and thought that all through before posing the question. The reason why I believe it will work just fine is because I have removed my 1000+ watt PPI amp and JL W-7 (my car has had enough of a beating), you installed car audio, so you know what kind of power I was dealing with. Even with that monstrous equipment, I had no voltage problems whatsoever.

 

[ChvyKc]

Thank you for the technical response. I totally agree with you 100% and thought that all through before posing the question. The reason why I believe it will work just fine is because I have removed my 1000+ watt PPI amp and JL W-7 (my car has had enough of a beating), you installed car audio, so you know what kind of power I was dealing with. Even with that monstrous equipment, I had no voltage problems whatsoever.

Yeah, I understand completely. The shop that I use to work for didn't sell JL, but our biggest competitor did and I had to know all the specs on that sub. That is one hell of a sub. I saw an Extera that had five of them in a custom fiberglass enclosure with a 1500 watt amp on each one and I'm suprised he didn't crack the back glass in that thing. It was just crazy loud.

Glad to hear that you are taking your stuff out though, I'm not into that stuff anymore. To much weight and it just beats the hell out of your hatch.

 

[Mist3r Spool]

I saw an Extera that had five of them in a custom fiberglass enclosure with a 1500 watt amp on each one and I'm suprised he didn't crack the back glass in that thing. It was just crazy loud.

That's a hell of a setup, I see similar setups out here in the Bay Area, CA every day.

OK, so I just finished my re-wire from the distribution block and it didn't work out too well. I'm thinking I have something wrong with my alternator at this point. I turned on the car and the fuel pump seemed fine. Then I hit the hazard button and it was running strong at first, until 5 seconds later, it started fluctuating with the lights...again! I'm thinking I need a better ground because I am just using the distribution block as a converter (if you will) from a 4-g monster cable to the 10-g fuel pump re-wire line.

 

[Mist3r Spool]

Update: I just re-wired the power cable to the fuel pump from the battery...same results!

So, do I need:

A) A new battery (I have a 2.5 year old piece of crap ProStart battery from PepBoys)
B) A new alternator (My headlights seem to dim a tiny bit when I press the brake @ idle)
C) A new battery + alternator

I've recently changed my alternator belt so I know it's not that.

I did a voltage check and was getting ~12.9-13.6 volts with all accessories on at idle and ~13.6-14.0 volts with the accessories off at idle.

 

[ChvyKc]

Update: I just re-wired the power cable to the fuel pump from the battery...same results!

So, do I need:

A) A new battery (I have a 2.5 year old piece of crap ProStart battery from PepBoys)
B) A new alternator (My headlights seem to dim a tiny bit when I press the brake @ idle)
C) A new battery + alternator

I've recently changed my alternator belt so I know it's not that.

I did a voltage check and was getting ~12.9-13.6 volts with all accessories on at idle and ~13.6-14.0 volts with the accessories off at idle.

Sounds like an alternator problem, but it is probably both. I would at least change the alternator depending on your budget, but you might as well get ready to change both. If you think about it, if the alternator is going bad then it is probably not feeding the battery enough voltage to stay charged, thus making it have to work harder to supply the electrical system with juice. So, like I said before, you are probably looking at having to replace both.

 

[Masochist]

Would also be a good idea to check the condition of the cables, clamps, and grounding conditions of your car. Have Autozone or someone do a free battery/charging system check and if it checks out ok, look specifically at your connections from the negative clamp to the body of the vehicle. I have fixed several light flicker/noise/operation problems by simply adding a braided ground strap to a battery.

As far as noise goes, anytime your sharing a common ground with a device such as an electrical motor (fan blower, fuel pump, etc.) you have potential for noise. Even the MECP study guides will recommend not using a factory ground bolt to ground something like a deck for the same reason. A fuel pump probably won't give you any issues with noise, but easy to check for and worth doing before finishing the job.