servion

So, I'm pushing back my fuel sump installation because its getting expensive. Last year, I maxed out my walbro 255hp intank pump at 524WHP (the pressure would drop off up top). This is weird because I have a 12gauge power wire running from the battery to the in-tank pump plate cover (the metal cover over the stock gas tank). I fixed that problem by adding a inline pump to supplement the walbro. I used one off of an old dragIII kit.

Now, I'm rewiring my pumps to use a relay instead of the ghetto way I'm doing it now. Here's the plan:

battery -> intank pump -> hidden switch (theft deterrent) -> relay (triggerred by stock fuel pump power wire) -> intank pump -> ground.

So, I have to have my switch flipped on, and then whenever the main relay triggers the fuel pump to come on, both my walbro and dragIII inline pump will kick on.

Here's my fear: It looks like the walbro intank will draw about 12amps at 80psi (50 base pressure + 30psi of boost /w a 1:1 regulator). If I assume the inline will draw the same amount of amperage, these bad boys wired in series like this will together draw 24amps of current. If I use a 10gauge wire to hook it all up, look at this page:
http://www.powerstream.com/Wire_Size.htm

Using the calculator on that page, if I start with 12 volts (I'll really start with 14v but the calculator on that page only lets you choose 12), and 15 feet of 10 gauge wiring I'll get a 1.4v drop inbetween the battery and the pump!?!? That's horrible... am I missing something here? I'd like to get a full 13.5-14V to the pumps.

Would it be better to run a separate power wire for each pump from the battery? Would it be better to run the power source from something like the underhood fuse box or alternator? Its hard to find connectors for the bigger gauge wires...

Also, should I run the power wire all the way to the actual pump INSIDE the gas tank, or just to the metal plate on top of the tank?

Kwuaymaikrup

This is how I did it. I ran a wire straight off of the fuse box with an inline relay to the pump. Wired the ecu to the relay so that it would turn the pump on like stock. I am however running an external pump but the wiring shouldn't be any different from yours. If I were keeping the intank I would do it just the same. As far as the metal cap question, I would think you will be OK as long as the wire from the cap to the pump is the same size as the wire from the battery to the cap. Does that make sense?

servion

That does make sense and that's the plan... the fear I'm having is the voltage drop over 15 feet of wire... its massive.

What gauge wire did you run?

dustin

Just run some of that huge car audio wire...

http://www.amplepower.com/primer/gauge/

dennis

I'd just run an a 8 gauge fused (or circuit breaker) wire from the battery. Once you got the 8 gauge to the pumps, you'll need to distribute it to some 10 or 12 gauge to wire up the pumps. The standard bosch relay is rated for 30amps I believe. Throw one in front of each pump and feed the ECU/fuel pump signal to the relays. You're golden. I wouldn't worry about the voltage drop, you're going to get all the power you need assuming your electrical system (alternator, etc...) is up to par.

servion

In the spirit of getting parts locally, I could use a pair of 10-gauge wires from the battery one to each pump, right? Even though they're attached to the same power source, they'll basically split the load between themselves, if I understand correctly.

Its a biatch to find anything bigger than 10-gauge connectors here locally (and they're a lot more expensive if youc an find them).

A pair of 30 amp rleays triggered by the same stock fuel pump power wire. So now, I either have to wire in 2 separate kill switches, or just don't run a kill switch at all. That a bummer, but proper fuel pump power delivery is more important than kill siwtches.

dennis

Put the kill switch on the ecu/fuel pump wire that feeds the relays. Just be careful you don't flip that bastard off whilst boosting.

2 10's would work if you couldn't find 8. You have a wal-mart there? I've gotten cheap *** amplifier wire kits from them. Most come with 10 gauge I think, but there may be a "high power" one with 8 or larger. Check there.

You could try a car stereo store, but chances are they're gonna rape you on wire prices.

I'd definitely focus on the proper power requirements before the kill switch.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by servion &raquo;</TD></TR><TR><TD CLASS="quote">In the spirit of getting parts locally, I could use a pair of 10-gauge wires from the battery one to each pump, right? Even though they're attached to the same power source, they'll basically split the load between themselves, if I understand correctly.

Its a biatch to find anything bigger than 10-gauge connectors here locally (and they're a lot more expensive if youc an find them).

A pair of 30 amp rleays triggered by the same stock fuel pump power wire. So now, I either have to wire in 2 separate kill switches, or just don't run a kill switch at all. That a bummer, but proper fuel pump power delivery is more important than kill siwtches.</TD></TR></TABLE>

V8MeatHead

If you hook everything up in series your going to still draw 12 amps of current total, not 24. Someone double check me, but i know im right. I think you want to hook them up in parallel rather than series.


Modified by V8MeatHead at 1:23 PM 4/28/2005





Modified by V8MeatHead at 1:27 PM 4/28/2005

dennis

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by V8MeatHead &raquo;</TD></TR><TR><TD CLASS="quote">If you hook everything up in series your going to still draw 12 amps of current total, not 24. Someone double check me but i know im right.</TD></TR></TABLE>

I don't think he was literally talking about wiring them up in a series circuit, if he did that, he'd be limiting the voltage across each pump to the tune of about 6-7v

dustin

Sure at half voltage hehe. The pumps probably wouldn't pump much of anything if they actually were in "series".

V8MeatHead

cool just double checking, not trying to be a *****

V8MeatHead

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by servion &raquo;</TD></TR><TR><TD CLASS="quote"> If I assume the inline will draw the same amount of amperage, these bad boys wired in series like this will together draw 24amps of current.
</TD></TR></TABLE>

Sorry your right, i was a little worried when he said this

servion

Correct me if I'm wrong...

by "in series", what I meant (in my original post) is that I will have 1 10-gauge wire that runs from the battery to the inline pump, to the relay, to the intan pump to a ground. This means that there is one wire from the battery feeding power to both units.... I thought that the amerage would be cumulative when in series like this.... 12 amps + 12 amps = 24.... perhaps this is wrong though.

What it looks like I'll do now:

Have 2 10-gauge wires... both connected to a + source in the fusebox. They will both run to separate relays, then to their separate fuel pumps and then to separate grounds. Both relays will be triggered by the stock fuel pump power wire. That way, even though they're both drawing from the same idential power source, they each have their own 10-gauge wire for recieving power. Does this sound reasonable? Should I fuse each of these power wires?

Will it be safe for me to actually run a wire with a ring terminal past the fuel pump accesss panel and into the tank to physically attach directly to the intank fuel pump?

V8MeatHead

You need to make sure you have the two postive leads of the fuel pump connected together and the the two grouds of the fuel pump connected together.
Wrong: |positive battery| (wire) +|fuelpump|- (wire) +|fuel pump|- (wire) |ground|

dustin

http://www.electronics-lab.com...s.htm

http://www.electronics-lab.com...l.htm

V8MeatHead

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dustin &raquo;</TD></TR><TR><TD CLASS="quote">http://www.electronics-lab.com...s.htm

http://www.electronics-lab.com...l.htm</TD></TR></TABLE>

Thanks I can't draw crap through here


Modified by V8MeatHead at 2:23 PM 4/28/2005

V8MeatHead

Ill stick with my conventional current direction

Edit: They've got some cool articles in there. Bookmarked!


Modified by V8MeatHead at 3:34 PM 4/28/2005


Modified by V8MeatHead at 7:06 PM 4/30/2005

V8MeatHead

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by servion &raquo;</TD></TR><TR><TD CLASS="quote"> Should I fuse each of these power wires?

pump?</TD></TR></TABLE>

Yes you should.

dustin

Hmm fuse them... but it might be a good idea to get some hobbs switches or something that ... eh.. cut ignition if fuel pressure drops below a certain point...

Or something. I'd just be afraid if one of the pumps crapped out but the other was still pumping away... hehe.

servion

Yeah, that would suck... but this is a temporary fix until I can $$$ to sump it

V8MeatHead

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dustin &raquo;</TD></TR><TR><TD CLASS="quote">Hmm fuse them... but it might be a good idea to get some hobbs switches or something that ... eh.. cut ignition if fuel pressure drops below a certain point...

Or something. I'd just be afraid if one of the pumps crapped out but the other was still pumping away... hehe.</TD></TR></TABLE>

Isn't fusing them a good idea? Something shorts and he may be fucked. Or too much current and melt the insulation on the wires, then eventually short.

Good point on that.

Kwuaymaikrup

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by servion &raquo;</TD></TR><TR><TD CLASS="quote">That does make sense and that's the plan... the fear I'm having is the voltage drop over 15 feet of wire... its massive.

What gauge wire did you run?</TD></TR></TABLE>

I am running 12ga. Tony1 uses it on all of his Aeromotive installs and recommended it to me.


Modified by Kwuaymaikrup at 2:03 AM 4/30/2005

SFWD 1934

Servion: Just out of curiosity how much do you think it will cost you to do the sump, as opposed to all of this headache you are causing yourself now? I would just keep boost/fuel managable for now, and then do the sump. Much better in the long run man, and less things to have to worry about going out on you under a full boost run. If not that, then you can always go with the Aeromotive fule pump voltage booster, or the MSD fuel booster via MAP pressure. But then thats another $200 bucks or so. Just sump it man.

Jason

*Boostwerks*

I thought you already had that aeromotive pump?

But Heres my "final" plan on the fuel pump delema...

I am going to tune the car with just the walbro HP255lph, and if it drops pressure up top, I'll add in a second inline pump. Since I have the 6an stainless line to the aeromotive filter, I can just add on a second pump straight to the filter. Easy install, and it takes care of the problem. I already have a relay wired in but the power wire is not connected. That way If I need the second pump, I'll just hook it up and have the relay power just this second pump.

servion

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SFWD 1934 &raquo;</TD></TR><TR><TD CLASS="quote">Servion: Just out of curiosity how much do you think it will cost you to do the sump, as opposed to all of this headache you are causing yourself now? I would just keep boost/fuel managable for now, and then do the sump. Much better in the long run man, and less things to have to worry about going out on you under a full boost run. If not that, then you can always go with the Aeromotive fule pump voltage booster, or the MSD fuel booster via MAP pressure. But then thats another $200 bucks or so. Just sump it man.

Jason</TD></TR></TABLE>

You're absolutely right... I's definitely prefer to sump it. I will sump it... the only issue right now is that it already has the 2 fuel pumps installed and I think I'm going to have to cough up the cash for a twin disc any day now. I'd like to be able to race my car before the season's over

With all these cars popping up with 600_whp with only walbro intank pumps, I figure I should be able to pull off 600whp corrected (I'm at 6000 feet altitude) safely until I can sump it. The inline pump is for that extra insurance. Once I get the cash to sump it, then I'll turn it up to shoot for 600whp uncorrected.

I figure that since the pumps are already there... I might as well wire them up correctly. LAst night I ran 2 separate 10-gauge wires like this:

alternator -&gt; 30A fuse -&gt; 30A automotive relay -&gt; fuel pump -&gt; ground.

I have 2 entire separate circuits like this (one for each pump). The relays are both triggered by the stock fuel pump power wire (i.e., main relay). This is also switched so that I have a kill switch as well. So as long as my kill switch is enabled, then I'll get full power to both pump directly from the alternator whenever the ECU tells the pumps to be on