How To Direct Wire A Fuel Pump? (7 Easy Steps)


How To Direct Wire A Fuel Pump

Do you know how to direct wire a fuel pump? Well, you are at the perfect place to find the answer to such a question.

There are various reasons why a person would want to direct wire a fuel pump to a battery. Perhaps the most common is because a person has tuned their vehicle and they want to ensure that their fuel pump has steady, consistent power.

Here are the steps you need to direct wire a fuel pump which include:

Step 1: Wiring In The Fuse

Step 2: Connecting The Battery To The Fuel Relay

Step 3: Grounding

Step 4: Cut The Wires From The Fuel Pump

Step 5: Attach Trigger Wire to Fuel Pump

Step 6: Attach Power Wire to Fuel Pump

Step 7: Put The Fuse In And Test

How to Direct Wire a Fuel Pump – Step by Step

As we said, direct wiring to a fuel pump isn’t going to be all that difficult. You will be doing most of your work around the relay, and it is just a case of looking at the numbers listed on the relay.

Do bear in mind that we are only able to give you a very general overview of how everything works here.

As you can probably guess, there may be small differences between vehicles and fuel pumps. We will try and give you an idea about what we are doing in each step.

This will allow you to try and match up to the wires that your vehicle has.

Step 1: Wiring In The Fuse

Your first job is to get the first wire connected up to the positive terminal on the battery. You will need to cut a short piece of wire for this.

One end is clipped to the battery. On the other end, you are going to solder your fuse holder.

You will want to place the 30amp fuse into the fuse holder when everything is done. Don’t do it until you have finished soldering.

Step 2: Connecting The Battery To The Fuel Relay 

Once the fuse holder is soldered in, you will want to solder a longer cable onto the end of it. This cable is going to be running all the way to your fuel pump relay.

That wire is going to terminal 30 on the fuel relay. If the relay doesn’t say what the terminal is, then look at the schematics.

Step 3: Grounding

Your ground wire will be attached to terminal 30 on the relay. The other end of the ground wire can be attached to a screw around the fuel pump area. 

Step 4: Cut The Wires From The Fuel Pump

Your wiring harness will be a single wire. You need to cut this into two.

Step 5: Attach Trigger Wire to Fuel Pump

Attach the trigger cable (black and white with blue stripes) coming from the fuel pump to terminal 86 on the fuel pump relay.

Step 6: Attach Power Wire to Fuel Pump

The final step is to get that power wire soldered to your fuel pump. This will be the second wire that you cut. You will want to attach this to terminal 87.

Step 7: Put The Fuse In And Test

Now that everything should be soldered into place, you will want to put that 30amp fuse in (remember the holder by the battery?)

Now turn your vehicle on. If you have soldered everything correctly, the fuel pump should work. If it doesn’t, then you may need to use your multimeter to double-check whether power is flowing through the cables.

If everything works, then you may want to sheath the wires so that there is nothing left exposed.

How To Wire Electric Fuel Pump Relay / Bypass / Rewire / Hardwire Upgrade >> Check out the video below:

Reasons For Direct Wiring a Fuel Pump

To be honest, there isn’t a huge number of reasons why you would need to direct wire a fuel pump.

The main reason is when you have tuned your vehicle. By direct wiring the fuel pump to the battery, you don’t have to worry about power fluctuations in your vehicle. Your fuel pump will be running almost constantly on good, clean power.

This means that you do not have to worry about there being dips in power, something that you would normally find in a tuned vehicle, and, thus, you can ensure that your fuel pump is going to deliver constant performance.

Some people may wire a switch between the fuel pump and the battery. They then use this as a kill switch.

if the kill switch is kept hidden, then it means people won’t be able to start your vehicle. Although do bear in mind that there are probably far better options out there for vehicle kill switches. 

What You Need To Direct Wire a Fuel Pump

You are going to need a fuel pump suitable for direct wiring to your battery. In most cases, you should be fine. Look at the voltage of your fuel pump. It should be 12-volt.

Most vehicle batteries are going to be 12-volt too. If you have a mismatch, then you may need to choose a different fuel pump.

On top of this, you are going to need to have a fuel pump relay. Chances are that you will have one of this inside of your vehicle already. Although, we suggest that you get yourself a new one.

They are fairly cheap, and it means that you won’t have to worry about taking wires off of your old relay, which could risk damaging it.

Just after the battery, you will need to be placing a 30amp fuse. So, pick yourself up an automotive fuse and a fuse holder to hold everything together.

You will need the fuel pump wiring harness for this. You should already have this. It would have come with your fuel pump.

Finally, at least on the hardware front, you will need some automotive wire. 6ga will be fine. Couple this with some automotive solder.

Tool requirements are minimal. You will need a soldering iron capable of dealing with automotive soldering jobs.

You may also want a multimeter, just so that you can do a bit of testing if something ends up not working.

Should You Get Your Fuel Pump Direct Wired By a Professional?

Direct wiring your fuel pump isn’t too difficult. In most cases, it really is just a case of splicing some wires and getting them connected to the battery.

Even if you do not have that much experience working with vehicles, you should be able to do it.

As with most car jobs, it is always worth taking the vehicle to a professional. They will ensure that the job is done properly. Direct wiring a fuel pump isn’t really something that should take too long either, so the price shouldn’t be that high.

This is assuming that you have a fuel pump that can be direct-wired to the battery. As we mentioned before, if your fuel pump works with something other than the voltage of your vehicle’s battery, then you may find yourself running into a couple of problems, but nothing too crazy.

Of course, we would recommend that you go to a professional. We have seen some pretty poor wiring jobs carried out on fuel pumps.

The problem with a poor wiring job is that electrical connections get hot. You really, really do not want to have a hot electrical connection by a fuel pump.

You are just asking for a fire. You will be able to get around this by properly sheathing the fuel pump wires.

Conclusion

If you have tuned your vehicle, then you may want to direct wire your fuel pump to your battery. Although, do bear in mind that it is unlikely to be necessary if your vehicle hasn’t been tuned.

Fuel pumps aren’t really designed for direct wiring.

If you do opt to direct wire, the process should take around 20-30 minutes. You won’t need much equipment beyond a soldering iron, solder, wires, and a fuel pump relay.

If you have all of that, follow the instructions on this page, and everything will be connected in no time at all.

References

https://deatschwerks.com/blogs/news/new-high-current-fuel-pump-hardwire-kits

Steve P.

Steve is an automotive technician, technical writer, and Managing Editor. He has held a lifelong passion for cars, with a particular interest in cars like the Buick Riviera. Steve is based in Boise, Idaho.

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