Electrical No fuel pump prime or start

[General karthief]

If you have power to that wire at the back by the tank you're dropping the tank.
Original fuel pump? Change it. Sometimes the plug at the top of the tank is fubar.
Either way you're dropping it.
Figuratively speaking of course

 

[AnthonyA1234]

It’s a pretty unused walbro pump i replaced about a year ago. I ordered a new pump and I’ll throw it in there and hopefully it works!

 

[Jarhead67]

I took my car to get painted and it ran great. Now I got it back and the fuel pump is not working… Any tips on how I can trouble shoot my way to finding the problem? I did a wire tuck so the pump relay and all those wires are all pretty hard to get to now. However I took the front bumper off and reached inside the fender where I hid the relay and I feel and hear it clicking. What else can I check?

Inertia switch is also good

Are you getting power at the inertia switch?

Are you getting power from the inertial switch?

You just need to figure out where you’re losing power.

If you have power to the wire going to the pump and it’s not running, then you probably have a bad pump.

 

[AnthonyA1234]

Bad news… I changed the pump and still no prime or start. Now when I check the power at the plug I am only getting 7 volts when before I was getting 12?? The battery has 12 volts so I don’t understand why now I’m getting 7 volts at the plug.

What do you guys think? Change the relay?

 

[AeroCoupe]

Work your way from the tank back to the fuel pump relay and see what the voltage drops.

 

[AnthonyA1234]

So where do I put the multimeter probes on the relay?

 

[AeroCoupe]

Wiring diagram:

Orange / Lt Blue wire will be the 12V+ from the fusible link at the starter solenoid to the fuel pump relay. The Pink / Black wire is 12V+ from the relay to the pump. The Red \ Black wire is 12V+ from PCM power relay and it also goes to Pin 33 on the ECU. The Tan / Light Green wire is ground from Pin 22 on the ECU. The ECU controls the fuel pump through this wire. It provides ground when you first turn the key to prime the pump and then provides ground when it “sees” that the motor is turning over i.e. when cranking or running.

Note that the Tan / Light Green wire goes to the test port and then to the relay. You can ground it at the test port with the key in the run position and see if the pump runs. If not does then I would suspect the ECU or the wire from the ECU to the Test port being bad.

 

[AeroCoupe]

Also, check this ground and make sure it’s in good shape.

This is the ECU ground.

 

[AnthonyA1234]

Wiring diagram:

Orange / Lt Blue wire will be the 12V+ from the EEC power relay to the fuel pump relay. The Pink / Black wire is 12V+ from the relay to the pump. The Red \ Black wire is 12V+ from Pin 33 on the ECU. The Tan / Light Green wire is ground from Pin 22 on the ECU. The ECU controls the fuel pump through this wire. It provides ground when you first turn the key to prime the pump and then provides ground when it “sees” that the motor is turning over i.e. when cranking or running.

Note that the Tan / Light Green wire goes to the test port and then to the relay. You can ground it at the test port with the key in the run position and see if the pump runs. If not does then I would suspect the ECU or the wire from the ECU to the Test port being bad.

Ok I will try that today. I tried grounding the test port before and nothing happened but I was probably doing it wrong. See my post 12. All I had was some wire so I just stuck it in there. Should it have worked this way or was I doing something wrong?

 

[AnthonyA1234]

Wiring diagram:

Orange / Lt Blue wire will be the 12V+ from the EEC power relay to the fuel pump relay. The Pink / Black wire is 12V+ from the relay to the pump. The Red \ Black wire is 12V+ from Pin 33 on the ECU. The Tan / Light Green wire is ground from Pin 22 on the ECU. The ECU controls the fuel pump through this wire. It provides ground when you first turn the key to prime the pump and then provides ground when it “sees” that the motor is turning over i.e. when cranking or running.

Note that the Tan / Light Green wire goes to the test port and then to the relay. You can ground it at the test port with the key in the run position and see if the pump runs. If not does then I would suspect the ECU or the wire from the ECU to the Test port being bad.

Alright so I took the fender off bc of my wire tuck and checked out the relay. First off I feel it click when I turn the key.

My wire colors are different than the ones in your diagram but these were my multimeter results…
With the key turned I had
Orange and black wire (I assume this is black and pink on diagram)- 12v
Red wire- 12v
Green/yellow wire- 0.04v
Light blue/orange wire- .3v

So is my problem the light blue orange wire? What does that mean is broken? The fuse link?

I’ve attached pics below of my relay and the wires going into it so you can see the color differences in the wires i mentioned.

 

[AnthonyA1234]

So I’m pretty stumped here guys I could use some help. So like I mentioned before only two out of four of the wires had power at my fuel pump relay. The ones that did not have power were the green one which is ground and the orange and blue wire which should have power. The diagram sent by aerocoupe says that the orange and blue wire has a fusible link so I started to track the yellow wire on the starter solenoid and find the link which connects to the orange and blue wire.

The problem is as you can see in my pic there are only 3 wires that come off the yellow wire and none of them are the blue and orange wire I’m looking for. So then I started tracking were the wire goes from the fuel pump relay from the passenger side. I did this and as you can see in the last pic it ends up in the testing port.

This is totally different from the diagram I have been looking at. If anyone could help me out I’d really appreciate it.

As you can see my yellow wire only turns into 3 wires unlike the diagram.

Then the orange and blue wire is no where to be found.

Then I found that the blue and orange wire doesn’t even connect to those starter solenoid area fusible links, it goes into the test port…

My car is a 1992 I’m not sure if the diagram you sent me is for a different year?

 

[AeroCoupe]

I pulled out the wiring diagrams for my 93. If your 92 had the fuel pump relay (FPR) next to the mass air then the wiring and colors are the same.

Dark Green / Yellow - starts at the FPR

then goes to Connector 12A581. From here is goes to two places. One wire goes back to the ECU on PIN 19 which is the “Fuel Pump Relay to Safety SW”.

The other wire heads to the Fuel Pump Inertia Switch. Then from the switch it changes color to Brown / Pink and goes to the fuel pump.

Red wire comes from your PCM power relay. See first picture.

Light / Blue Orange wire goes from the PIN 22 on the ECU

to the data connector

and then from there to FPR. See first picture.

Pink / Black wire goes from the FPR (see first picture) to an 18 ga Brown fusible link at the starter solenoid.

Hope this helps.

 

[AnthonyA1234]

I pulled out the wiring diagrams for my 93. If your 92 had the fuel pump relay (FPR) next to the mass air then the wiring and colors are the same.

Dark Green / Yellow - starts at the FPR

then goes to Connector 12A581. From here is goes to two places. One wire goes back to the ECU on PIN 19 which is the “Fuel Pump Relay to Safety SW”.

The other wire heads to the Fuel Pump Inertia Switch. Then from the switch it changes color to Brown / Pink and goes to the fuel pump.

Red wire comes from your PCM power relay. See first picture.

Light / Blue Orange wire goes from the PIN 22 on the ECU

to the data connector

and then from there to FPR. See first picture.

Pink / Black wire goes from the FPR (see first picture) to an 18 ga Brown fusible link at the starter solenoid.

Hope this helps.

Thank you

Ok that checks out with everything my car has then besides how the wire in my relay is orange and black instead of black and pink.

Does that diagram mention which wires should have 12v and which should not at the relay? I’ve seen some people say the dark green should be 12v and the light blue orange should be 0v and vice versa…

My car had 12v at the black and orange, and the red. So I’m trying to see if it’s the light blue or the dark green wire that’s the problem

 

[AeroCoupe]

Think about it. The light blue / orange wire is ground coming from the ECU. This is the trigger wire that activates the relay and is on the coil side of the relay. The other side of the coil have to have 12V+ which is should have from the red wire which is from the PCM relay. The pink black wire should have 12V+ at all times being it gets its power from the battery side of the starter solenoid via the battery. The black pink wire has 12V+ only if the coil is energized and this is what powers the fuel pump via the inertia switch. Make sense?

 

[AnthonyA1234]

Think about it. The light blue / orange wire is ground coming from the ECU. This is the trigger wire that activates the relay and is on the coil side of the relay. The other side of the coil have to have 12V+ which is should have from the red wire which is from the PCM relay. The pink black wire should have 12V+ at all times being it gets its power from the battery side of the starter solenoid via the battery. The black pink wire has 12V+ only if the coil is energized and this is what powers the fuel pump via the inertia switch. Make sense?

Ok I gotcha. Sorry this is my first time doing any kind of electrical work on a car so I need everything explained to me like I’m a child lol.

I believe you got the orange and blue wire and the green/tan wire descriptions mixed up in your post 27

 

[AeroCoupe]

Good catch and corrected. Chasing wiring can be tedious. Hang in there.

 

[90sickfox]

How'd your testing turn out ? We had a previous member with a similar issue. It ended up being a corroded wire at this connector behind drivers kick panel.