99Taco no power to fuel pump

I have a 1999 Tacoma Sr5 4x4 with a 5 speed manual transmission powered by a 2.7l i4 and for some reason I’m not getting power to the fuel pump. I’ve pulled the dash out and removed the fuel pump I’ve checked the fuel pump relay and replaced it and I’ve also replaced the EFI relay just because but I’m still not getting power to the fuel pump. I’ve tested the pump and it is fully functional. Does anyone know what might be causing it. I was thinking either a loose connector or a broken wire and maybe even the ecu

 

The only time you will get power to the fuel pump is when you are cranking it or it’s running.FYI

 

Does the tach move when cracking?

 

I know about the cranking part, I had my brother crank it when I was testing it. I don’t think the tach was moving at all if I remember correctly

 

The ECM will not ground the FC side of the relay if there is no crank signal.

 

So are the crankshaft and camshaft sensors good then and or the wires or connections,
Also all your ground straps are good?

 

I haven’t tried to check my grounds but the only ground that I’ve touched was the battery ground which I’ve upgraded to a starter wire

 

And I haven’t touched any of the cam sensors but I’m not getting a check engine light at all, I’ve scanned it and I’m not getting any codes

 

Are you saying you never see a CEL?
With the key ON, and engine OFF/(Not Cranking), does the CEL come on?

 

Check to see if you have a crank signal then.

 

How do I check for a crank signal, I do have the CEL on when I put the key to the on position but whenever I run my obd2 reader I don’t get any codes at all.

 

Look at live data on the scanner.
Look for the RPM data PID, and see if it reads any RPM while cranking.

 

If the above checks dont bear fruit the connector that sends power for fuel pump and tail lights is under the drivers seat beneath the carpet. Remove the drivers seat its just 4 bolts, pull back the carpet you will see a white (i think 20 pin connector) the white wire with black stripe is the ground and iirc the pump hot wire is solid blue or solid purple you’ll be able to tell cuz its one gage heavier than the others.
Disconnect it and inspect for corrosion and arcing, you can also check for voltage while cranking.
good luck
R/

 

Thanks I didn’t know about the connector under the carpet. I do know what it randomly works since I got it working for about 20 mins but then it died while I tried to drive it around the block it’s stalled out since it was starved of gas and now it’s not working again. I’ll take a look at both of the things that y’all told me to, I also noticed that now the gas gauge doesn’t work so I’m thinking maybe my cluster is going out causing the pump to shut off maybe? I have an extra cluster I can swap out if needed. But I’ll test the rpm and look at that connection under the carpet.

 

The fuel gauge doesn’t have the ability to shut off the fuel.
Are you sure you have enough fuel?

You could jump the relay and test the pump.
If jumping the relay causes the pump to come on. It is not a connection issue under the seat.

 

I’ve pulled the pump out and tested it outside the car and I know what the tank is half full but when I test to see if I’ve got power at the connector for the pump I’ve got nothing but randomly I’ll get some power for a bit then it just dies completely

 

The relay for the pump is under the dash.
I’d see if you have power to the White/Red wire with the key ON.

 

I have replaced that relay but it didn’t end up changing anything, I’ll check if I have power coming from that though.

 

Power comes in on the Red/White wire and out on the Blue wire.

 

Does your truck have an aftermarket alarm system? If so remove that and solder the wires back to factory. How did you determine your fuel pump isn’t getting power? Continuity, OHMs, Voltage? Did you bench test the fuel pump? Things I would inspect after that; fuel pressure, fuel pressure regulator, fuel injectors, fuel filter, fuel lines, IAC, TPS, Mass air flow sensor, igniter, ignition coil, distributor, distributor cap and rotor, and any shorts in the ignition system. It’s rare the ECM took a dump, but it does happen.