Gadd

Yup

The way rxcited2 and I did the mod is the same. In one post he mentions that I ran a wire to the battery, but I did not. I used the spare fuse holder with the existing powered bus bar. It appears that rxcited2 extended the Blue wire with a butt connector and a bit of red wire, to reach the spare fuse holder slot. but that's the only difference I can see.


Paul

tt7hvn

iTrader: (5)

i have a quick question:

by the stock system, if you smack into a tree and wreck the car a fire breaks out and the ignition is still on, the fuel pump will still be pumping right?----huge safety hazard

by this wiring it doesn't seem to correct that issue; it seems the main concern with this project is voltage and performance opposed to also having safety in mind.

so, does the ignition still power the pump?

theorie

iTrader: (31)

if you use the stock fuel pump power wire from the harness as the signal wire for the relay, YES.

tt7hvn

iTrader: (5)

so even with this mod, the power from the ignition energizes the coil on the relay instead of the fuel pump itself as in stock form. but considering we have a direct line from the battery to the relay, which the ignition is energizing, the fuel pump will keep fuel pressure all the time when the ignition is on, the car doesn't necessarily have to be running

this could very bad when the fuel pulsation damper fails

just my .02

i'll see if i can figure a way to get around this guy...NEW PROJECT

AchillesGr

iTrader: (1)

hi,
where can i find info about this mod?
the link in the first page does not work!
thanks!!

tt7hvn

iTrader: (5)

^on the 8th page of this thread there is a wiring diagram on how to do it.

BlinD26

iTrader: (27)

For those of you that have seen my build thread, I had some erradic fueling issues on the dyno so I'm getting ready to rewire my fuel pump to rule out voltage issues. Only problem is I'm on the fence as to which method to go with...

The 'stock fuse' method seems the easiest by utilizing existing power feed with a empty fuse slot, but even though you are triggering the fuel pump relay with a direct 10 gauge feed from the battery, the long haul wire run to the pump is still the same stock gauge.


The other school of thought is run a 10 gauge wire straight from the battery to the back of the car have another relay in place triggered by the stock fuel pump trigger wire, which seems a bit redundant.


Has anyone meshed the two rewire methods? Maybe run another thick 10 gauge wire off the existing relay to eliminate the stock wireing and still add the additional ground @ the pump?

Any thoughts/ideas would be great since I'm looking at doing this in the next week or so.

BlinD26

iTrader: (27)

bump for input...

Macen

+1

rxcited2

I only did the first part of the mod which provides power to the relay contacts - when the relay closes, it delivers this power to the FP. This is the new +12v fuse installed in the empty slot in the main fuse box (shown in that photo, my photo BTW). It's not true that this power "triggers" the relay. The ignition switch triggers the relay and when it closes, this hot power wire is "delivered" to the FP. This is the most important part because otherwise the FP hot power is going through the ignition switch. Ignition switches are notorious for getting flaky over time, causing resistance and intermittence to anything going through them.

It's true the wiring from the relay back to the FP "might" be inadequate. I'd say it is actually fine, provided it is in good condition and all connections are sound. So the easiest/most effective method is to do the simple short new fuse power modification and check and clean all connector contacts between there and the FP.

If I were going to bother running any new wires, I would run a pair of beefy red/black wires directly from the FP relay under the hood, all the way back to the FP. There is no point tapping into any existing wiring or using the chassis ground if you are trying to minimize resistance.

One caution on running new wires is to read and understand the electrical diagram carefully before doing this. There is a high/low power relay that the ECU uses to deliver less voltage to the FP when you are not boosting. Delivering full voltage all the time would make the FP more noticeably noisy when idling or quietly cruising and possibly lower the FP lifetime. But I guess if you are a fanatic, you still might want this and would bypass even that.

mefarri

iTrader: (2)

Ok so let me ask a couple questions based off this design.

First, what amp fuse?

I'm going to use a Bosch 044 Fuel pump for the record. Now, I'm looking at this and am noticing that although there's 10 ga wire up to the connector, the connector down to the fuel pump is still the small factory wire. So I'm trying to figure out how to wire it all with 10 Ga wire.

I understand the big red wire powering the relay at terminal #30, the factory red/white wire turning the relay on at terminal #86 (doesn't matter wire size here as it's just a signal wire), and the ground off the relay at terminal #85.

Now, I had the idea to use these bulkhead connectors shown here:
http://www.summitracing.com/parts/MOR-74145/

So, if I was to do that, I can run a new 10 ga wire from the pump, to the bulkhead, then from the bulkhead to the #87 terminal on the relay. (pink wire in the pic) That would make the power side all 10 Ga. Good.

The questions I have are about the ground side.

Since I'm not using the factory connector, instead of just running an additional ground wire off the factory ground wire (which ins't being used) , could I just run a 10 ga wire from the pump to the bulkhead, then from the bulkhead to the battery? (relocated in passenger bin) And for guys who don't have their battery relocated, could they just ground it to the car like the relay ground off terminal #85?

Doing it this way would allow for ALL 10ga wire powering and grounding the pump plus it would leave the ability to trace back issues through the factory turn on wire. You'd still have to connect the factory connector so the fuel level gauge would work though, so don't forget that and go lopping off the connector.

rxcited2

Dudemaanownsanrx7 will have to explain his figure.

As for the fuse size, I took the one that is used for the FP already, pulled it from it's stock location (from the driver's side kick panel fuse box), and used it in the main fuse box under the hood. I forget what size it was, but I think it was yellow (15 Amp?) If your aftermarket pump uses significantly more amps, you might change that. 15 Amps should be overkill and only blow if your FP shorts out.

Dudemaaanownsanrx7

iTrader: (23)

Yeah pretty much any size fuse between 15-30 amp will work. 10g is pretty stout wire, and the fuse just protects the wire.

Bulk head connectors are a good way to bring 10g all the way to the pump. I used grommets and fuel safe sealant which works for me, others have had fuel push up through the wire doing it this way, the bulk heads would be cleaner and prevent this issue.

For most aftermarket pumps there is probably minimal gain running 10g all the way. The small factory wire is last in line and is pretty short, so resistance loss is much lower in comparison to the stock wiring that goes the length of the car. Large aftermarket pumps and dual pump setups definitely need the larger wire all the way to the pump(s).

arghx

iTrader: (3)

On my fuel pump rewire I used Brent's style of wiring and actually ran 8 gauge all the way into the tank for a Supra pump. I guess I'm just hardcore like that. The factory power wire triggers the relay and the factory ground wire has been completely replaced.



I didn't bother with bulkhead connectors, I just drilled 1/4" holes for the power and ground, and stuck some RTV around it. I guess it's a little ghetto looking but it's been working for over two years. I cranked my old T04S up to 21psi and the fuel pump seemed to be flowing enough.

My buddy who originally helped me with this install had to one-up me so he ran 4 gauge to the Walbro pump in his GMC Syclone setup.

mefarri

iTrader: (2)

arghx,

Not being a dick but someone needs to tell you that's uber unsafe and lazy. And in no way will any fuel pump EVER need 4ga wire. That's ridiculous. What did he use, Stinger terminals for connecting?

NOW,

Dudeman, can you confirm my questions about the ground? I'm pretty much positive I'm right but just wanna make sure.

Macen

My JDM car from 1995 has one slot free.

rxcited2

These are good idea if you plan to run heavy wire all the way to the pump. The ones that mefarri listed are kind of large (they're used for battery connections), but Summit also has a smaller one:

http://www.summitracing.com/parts/SUM-G1431

Looks a little more reasonably sized and is cheaper too.

I take it back the hole size is the same - a huge 1-1/4 inch hole each. Though the smaller ones are cheaper!

Dudemaaanownsanrx7

iTrader: (23)

Yeah you can ground it to the battery or to the frame, doesn't much matter it's not a ground sensitve signal wire it's just completeing the circuit. Just make sure on the frame that it's down to metal and actually a good ground point. There are a few bolts in there that make good ground points if you sand down the paint. I use electric grease too.

Julian

iTrader: (14)

This is not a safe practice; most common cause of electrical fires is chafe through wiring.

A 12 gauge bundled wire loom will support 20 amps continuous and would have a 3% voltage drop over 11 ft length.
Going to a 4 gauge would support 140 amps (starter loads) and would have a 3% voltage drop in 50 ft.
A compromise on size and weight would be a 10 gauge wire good for 27 amps continuous and about 18 ft for a 3% voltage drop.

As to ground wire, it is a waste of money and time to run the wire back to the battery. The chassis is the ground for the car, all that is needed is a cable equal in size to positrive wire and a clean ground connection close to the fuel pump. This is not an electronic device sensitive to noise and ground voltage differentials, its a pump.

Most electrical greases are di-electric, meaning they DO NOT conduct electricity. They are best applied after connection made to seal out moisture.

mefarri

iTrader: (2)

Cool. thanks guys.

staticguitar313

iTrader: (2)

Just sharing, I finished my re-wire today, made a nice and neat harness for mine and located the relay on an existing bracket.

Oscypek1007

iTrader: (1)

ok sorry for bumping this thread, but i have my pump rewired at the moment using this method


should I also rewire it the method that is shown in this thread as well?

again sorry for the bump my head just hurts from reading both rewire threads ten times over.

Gringo Grande

iTrader: (97)

Quoted for great justice! I'm about to double check the (I highly suspect based on the other "wiring" in the car") poor Fuel Pump rewire in my car by the PO.

$lacker

iTrader: (9)

This seems like the best way to do it
Is it possible for rx7club.com to back up photos in important FAQ threads like this? In 5 years it would be nice if these things were still viewable for people

Dudemaaanownsanrx7

iTrader: (23)

You do not need to do both ways, the way you have it is fine and will give full voltage to the pumps.