As much as we love cars, they’re not perfect. Even high-performance, reliable vehicles have their fair share of issues despite years of automotive innovation. For example, modern fuel injection systems may be state-of-the-art technology, but they still malfunction every so often.
A common issue that fuel injection systems suffer from is shoddy fuel pump relays. Relays are integral to your car’s operation, but it is possible – and safe – to bypass them. However, keep in mind that bypassing your relay should only be a temporary fix to get your car running.
Anytime you open up your car hood to make changes is risky, but not if you know what you’re doing. Similarly, bypassing your fuel pump relay isn’t dangerous for your car, so long as you do it correctly. Keep reading to learn more about bypassing fuel pump relays before trying it yourself.
Is it safe to bypass your fuel pump relay switch?
Owners should always replace a fuel pump relay switch rather than bypass it; this is an ideal case. Ensuring that your car’s electrical systems run correctly is a part of good car maintenance, so quickly solving this problem is a top priority. Sometimes, though, you need the car running before you even can get a new relay.
When you need your car running ASAP, it’s safe to bypass your fuel pump relay with a jumper wire. However, using a jumper wire to bypass a relay directs a constant flow to your fuel pump, even when your car is off. This can have adverse outcomes for you and your car’s well-being.
While not common, accidents can happen when bypassing fuel pump relays. You should always be cautious when working with an open electrical current, that’s a given, but accidents can happen even after successfully bypassing fuel pump relays.
Crashing with a Bypassed Fuel Pump Relay
As we mentioned previously, a serious implication of bypassing fuel pump relays is that fuel pressure is manually controlled rather than automatically. You can remove the jumper cable when you turn off your car, but what if you can’t access the fuse box as usual?
In an accident, a relay would typically drop fuel pressure after the ECM detects a crash. But without a relay to communicate with the ECM, fuel pressure remains high after a collision.
Nearly totaling your car can split open a pressurized fuel line that’ll spew out gasoline like a water fountain. And depending on your accident’s severity, a fire may have ignited, and your fuel tank is now pouring out gasoline. You can kiss any hope of salvaging your car away at this point.
Forgetting to Remove the Jumper Wire
While not catastrophic, forgetting to remove the jumper wire from your fuse box is an easy mistake to make. Current constantly flowing through your fuel pump not only wears it out but drains your battery too. Either of these outcomes leaves you with a much bigger problem than a bad relay switch.
The Cost of Bypassing Fuel Pump Relay
Bypassing a fuel pump relay is relatively cheap. Relay jumper cables are simple to make with supplies that cost you less than $30 from an auto shop. Of course, if you happen to find yourself in an accident with a bypassed fuel pump relay, then the costs go up. However, the price of bypassing a relay alone is minimal.
To create a relay jumper cable yourself, you’ll need:
- 16 Gauge Primary Wire (at least 5-6”)
- 16-14 Gauge Male Disconnects (x2)
- Needle-nose Pliers
- Wire strippers or a utility blade
- Electrical tape
Once you have everything you need, check out this video showing how to create a relay jumper cable—
You may question whether it’s worth spending the time looking for these items instead of just buying a new relay. And you’d be right. If you’re already at an auto store, chances are they sell fuel pump relays, and you could buy it there. But if your car calls for a specific model that you have to order, then this is an excellent alternative for the time being.
Depending on what type of relay your fuel pump system calls for, relays can cost anywhere from $4-$50. They’re easy to remove, replace, and install, so you shouldn’t be running your car with a bypassed relay for the long term. And even if you’re worried about getting under your car’s hood yourself, an auto shop mechanic wouldn’t mind ordering and replacing the part for you.
How Older Cars Functioned Without Fuel Pump Relays
Before modern fuel pump systems, cars used carburetors. As a fuel pump system, carburetors helped regulate fuel pressure before electronic systems became standard in automobiles. Carburetor systems used analog technology very different from the fuel systems found in today’s cars.
This is what the best Ford Thunderbirds, best Plymouth Barracudas, and best hatchback Novas used back in the day.
Put briefly, carburetors use basic air pressure engineering to create the correct fuel-to-air ratio in an engine. However, the shift to fuel-injection systems eliminated the need for carburetor systems despite carburetors being cheaper to create.
Fuel-injection systems are electrically based and allow for higher performance. Your car’s ECM, or PCM, controls electrical circuits and components throughout your car— like the fuel pump relay switch. Without this switch, the fuel pump never receives a current, which is why your engine won’t start.
Should you hire to bypass the fuel pump relay?
As we mentioned already, bypassing a fuel pump relay is not difficult at all. It doesn’t take much time or expertise beyond knowing which terminals need a jump connection. Relay switches have this information on them already, but if figuring this out is difficult for you, roadside assistance is your best bet.
If you can hire a tow truck driver to bring your car into the shop for you, and they don’t have your model’s fuel pump relay in stock, then you can ask a mechanic to bypass it for you. It’s always better to have a professional take care of something like this if you don’t have time to research how to do it.
Keep in mind, though, that this process is simple, quick (less than 5 minutes), and doesn’t require extensive automotive knowledge: simple research can bring up several guides to bypass your fuel pump relay.
Here is a video demonstration:
But again, if you don’t feel comfortable, there’s no shame in calling up a trained mechanic.
Once again, it is absolutely safe to bypass your fuel pump relay switch. Anybody with the right tools and access to material can bypass the relay with a simple jumper cable. While we recommend replacing your relay quickly, don’t hesitate to bypass the relay switch if you desperately need your car running again.
Repairs are inevitable. So, it is best if you can identify issues and troubleshoot to minimize stress in your life.
Here are some other issues you may want to read up on to make sure you have some basic understanding before the issue comes up—