So last week something happened that I’ve never had happen before. I was dropping my daughter off at school and I noticed that my dash lights weren’t on. My headlights still worked and the blinkers did to.
When I got home and parked it, I checked out all the fuses. There was a 20 amp fuse that was blown, so I replaced it and then checked the relays under the hood. I turned on the key to check the dash lights and they still didn’t work. The 20 amp fuse blew again, so I replaced it again. Now the dash lights work again.
However, when I tried to start it, it would turn over, but the fuel pump isn’t turning on.
Long story short, I’ve replaced all 4 relays under the hood, installed a new fuel pump and also replaced some bulbs in my taillights and sides over the front tires. It turns over when I try to start it, but the fuel pump still isn’t “kicking” on and it won’t start. I feel like somehow, power isn’t getting to the fuel pump.
Does anybody have any ideas on what I could check next? I’m all out of ideas.
The 20 amp fuse blowing means you have a short. Replacing fuses and breakers isn’t finding and fixing the short circuit. There is a problem with the circuit with the 20 amp fuse. Look for some burnt or melted insulation on the wires for whatever is powered through that fuse.
Remove the gas cap, and listen down the filler tube while someone turns the ignition switch to the run position. You should hear the fuel pump run for a second or two and then shut off.
If you don’t hear anything, check the fuel pump fuse, fuse #1/30 amp.
Finding wiring problems is a pain, my son has a 1998 Wrangler and we lost the headlights a few years ago and the starter recently. In both cases the wiring at the bottom of the fuse/relay box had come loose. The factory crimp was too tight or the wires were nicked and they came apart. You are facing 20+ years of corrosion. You have to find a working spot in the wiring and start tracing back till you find the problem.
There’s a relatively inexpensive test gadget you can buy which helps isolate problems like short circuits. I think this is the one I’ve seen before
If the fuel pump isn’t turning on when you think it should, ask your shop to measure the voltage right at the pump connector. It’s not an uncommon thing for those fuel pump connectors to fry from over-current conditions, so they could take it off and look for signs of burned contacts too. If the contacts looked fried, suspect a clogged fuel filter. That can overload the pump.
Car engineers put in safety stuff to prevent the pump from running in certain conditions to prevent fires, like if it thinks the engine isn’t tuning, or if it has detected a crash. So good idea to check the crank sensor and the inertial safety switch, if you have them.
George, that is apparently a 0-30 amp ammeter with leads designed to clip to fuse contacts. Apparently it has only the one range. I wonder what happens when you use it in a circuit with a real short, where the current can reach above 100 amps? Hopefully it has an internal fuse.
I suspect you have now blown a fuse in the panel under the hood. Make sure all the fuses are good. It is best to use a test light probe to verify power is getting the fuses. Use the slits on top of the small fuses to place the probe tip on to. You should also verify that the fuses in the dash panel are getting power to them with the ignition turned ON.
All the things you replaced were most likely good. You didn’t seem to verify power was getting to the areas you worked on before replacing them. A very common mistake.
George, that is apparently a 0-30 amp ammeter with leads designed to clip to fuse contacts. Apparently it has only the one range. I wonder what happens when you use it in a circuit with a real short, where the current can reach above 100 amps? Hopefully it has an internal fuse.
When I read the description of how it works on the packaging on a visit to HF one time, it seemed like it might be very helpful diagnosing and narrowing down the cause of electrical problems in autos, like phantom draws and shorts. I don’t know if it has an internal fuse or not though.
Circuit testers (should) have a built in automatic resetting circuit breaker. A 30 circuit tester could melt the vehicles wiring when testing a circuit protected by a 20 amp fuse. My circuit tested (old) has a 12.5 amp circuit breaker, it reacts quickly to a shorted circuit however locating the short could take 10 minutes or it could take 2 hours for someone experienced, could be days for someone who is not.
@ThatDigiGuy If the tail light fuse was blown normally I would first look for aftermarket trailer hitch wiring. If the fuel pump fuse is blown now I would suspect damage to the wiring harness to the rear of the vehicle. Inspect the wiring harness on the sides of the front seat foot wells and along the inside edge of the rear quarter panels , the wiring is mostly exposed on this vehicle.
I’ve found short circuit locations before using a magnetic compass. I’ll enable the suspect circuit, maybe put a resistor in series to limit the current to a reasonable number if it is a dead short, then I’ll follow the current path using the compass needle. At the place where the short occurs, the compass needle will no longer align with the wire’s magnetic field. This doesn’t always work, for example the current might come back the way it went so the magnetic fields cancel. Or there’s current in another circuit also causing magnetic fields. But it sometimes is a fast way to find where the short occurs.