Help! Fuel pump not turning on.

Steezin636 · Dec 13, 2024

Hey everyone!

First time post here. I inherited a 1989 foxbody 5.0 with 72k original miles a couple of years ago. Admittedly life has been busy and have not touched it since I parked it in the driveway. Did a fresh oil change, charged the battery, and went to go start it up and it’ll crank all day long but won’t fire up.

So I started doing some research and started trying to diagnose my issue. It’ll start for a split second with a spray of starter fluid so I know I’m getting spark.

I began going down the rabbit hole of figuring out fuel delivery issues. The relay under the driver seat clicks, inertia switch passed its test. I’m getting 12v at orange/blue wire, 12v at red/black, 12v at tan/green, and 1.46v at pink/black.

I know pink/black is the wire to supply power to the fuel pump. I tried to bypass the relay and connect the red/black to pink/black but had no luck.

Any ideas or help would be much appreciated.

LILCBRA · Dec 13, 2024

Is it getting fuel pressure? If it is, I'd say that the fuel in the tank is bad. Your best bet would be to siphon the old fuel out and replace it with fresh. You'll also want to clear the lines when you do that. The easiest way that I've found was to disconnect the lines at the engine and cycle the key a bunch of times until fresh fuel starts spitting out. You'll obviously need a couple tools to get this all accomplished, these are my recommendations:

Multi-Use Transfer Pump

Amazing deals on this Multi-Use Transfer Pump at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Amazon.com

LILCBRA · Dec 13, 2024

Now, if you're not getting pressure and it sounds like everything else is checking out, you may need to drop the tank and replace the pump. If that's the case, you'll probably still want that siphon pump but I've been able to do everything else with basic hand tools.

Steezin636 · Dec 13, 2024

I tried to siphons the fuel out last night because I was anticipating it being a bad fuel pump but decided to do a deeper diagnosis first. The fuel gauge says full so I bought a similar pump to what you posted and put the hose in there to start siphoning and got nothing. So I grabbed a 5gallon fuel tank and added 5 gallons and it didn’t overflow… so obviously the fuel gauge is off.

As for checking fuel pressure I will do that… but I’m not hearing the fuel pump priming at all and I’m not getting correct voltage to the power wire for the fuel pump…

LILCBRA · Dec 13, 2024

Sounds like a new pump is in order from what I can gather. Maybe someone else will chime in and give you a different idea on what to look at.

I let my 87 sit for a couple years and had to siphon the fuel to get it running again, but I can hear the pump prime.

Steezin636 · Dec 13, 2024

I just rigged together something to hotwire the pink/black wire. Will update with the result on that.

Steezin636 · Dec 13, 2024

Well that did nothing. I don’t want to drop the money on a fuel pump if I don’t have to. If anyone has any other suggestions I’m open to try anything.

Even with 12v to the pink/black wire still didn’t hear the fuel pump. Everything that I can think of is pointing towards that being the issue.

Mcmahst · Dec 13, 2024

If you remove the tank and pump, you might find the pump full of crud and may be able to clean it. Just a thought. I always try to fix things before I buy the replacement, even if it unlikely. Good luck.

Steezin636 · Dec 13, 2024

Thank you for the advice. I will give it a shot. I wonder if the pump would still make priming noise if it was clogged like that?

Rdub6 · Dec 13, 2024

LILCBRA said:
Is it getting fuel pressure? If it is, I'd say that the fuel in the tank is bad. Your best bet would be to siphon the old fuel out and replace it with fresh. You'll also want to clear the lines when you do that. The easiest way that I've found was to disconnect the lines at the engine and cycle the key a bunch of times until fresh fuel starts spitting out. You'll obviously need a couple tools to get this all accomplished, these are my recommendations:

Multi-Use Transfer Pump

Amazing deals on this Multi-Use Transfer Pump at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Amazon.com

I’ve always had trouble with the hose on those pumps curling up, and then they’re not getting to the bottom of the tank. Anybody have any tricks that worked to get that hose all the way to the bottom?

AeroCoupe · Dec 13, 2024

Have you checked the wiring harness connection just above the fuel tank?

Engine Post in thread 'Intermittent CEL with loss of power'

Sep 13, 2024

There is a connector between the body harness and the fuel tank harness. This connection is located under the car and behind the bumper. The fuel tank harness has a clip that hold it to the fuel tank on the fuel tank seam and just beyond this is the connector. This is a picture of the connector separated:

This is a picture of it connected. You can see the clip holding it to the tank in the top left and the connectors are top center.

This connector can corrode and cause loss of connection for the fuel pump and/or the fuel gauge sending unit.

The other thing...

If that checks out then drop the tank. Nothing else to do but that to further figuring this out. While you have the tank dropped you should probably install a new fuel neck seal and look the vent over as the seal around them tend to leak as they age.

Steezin636 · Dec 13, 2024

Yes , I separated that connection and am getting the same voltage on there that I’m getting at the fuel pump relay… unless the post you referenced is talking about deterioration at the connection where it makes its way to the pump. I’ll have to drop the tank and check the wires at the pump to see if it’s making it that far I guess.

Steezin636 · Dec 13, 2024

Rdub I believe mine was twisting in the tank also. I tried to siphon out the 5 gallons I added last night and nothing came out. I will just use a piece of 2x4 and a jack to assist in lowering the tank I suppose.

Steezin636 · Dec 13, 2024

AeroCoupe said:
Have you checked the wiring harness connection just above the fuel tank?

Engine Post in thread 'Intermittent CEL with loss of power'

Sep 13, 2024

There is a connector between the body harness and the fuel tank harness. This connection is located under the car and behind the bumper. The fuel tank harness has a clip that hold it to the fuel tank on the fuel tank seam and just beyond this is the connector. This is a picture of the connector separated:

This is a picture of it connected. You can see the clip holding it to the tank in the top left and the connectors are top center.

This connector can corrode and cause loss of connection for the fuel pump and/or the fuel gauge sending unit.

The other thing...

AeroCoupe

If that checks out then drop the tank. Nothing else to do but that to further figuring this out. While you have the tank dropped you should probably install a new fuel neck seal and look the vent over as the seal around them tend to leak as they age.

I got codes 95 and 96 on my CEL, from my research it seems like those codes reference a failure for the voltage for the circuitry for the fuel pump

Mcmahst · Dec 13, 2024

I’m not 100% sure, but I suspect these pump have a low torque capacity. So, any particle could jam or clog the pump vanes. And the priming noise is just the pump building pressure, so it’s running. If it’s clogged or jammed, it can’t do that. But as others have said, it all starts with dropping the tank. Good luck.

Steezin636 · Dec 13, 2024

Will drop the tank tomorrow, and report back here. Thanks everyone.

AeroCoupe · Dec 13, 2024

Code 95, Post #2:

R

Thread 'Code 95. What is considered the Secondary fuel pump circuit'

Jul 24, 2020

So I have the legendary stumble, hiccup, misfire... what ever you wanna call it issue. Comes up with code 95. So what is considered the "secondary fuel pump circuit" vs primary. The only other codes are egr.
93 LX 5.0 T5

Code 96, Post #4:

Thread 'Code 96 Repair:'

Apr 1, 2011

Got a code 96 on a 1990 Mustang GT. Replaced the fuel pump relay and got the pump from running on continuously. But, for some reason, I keep getting the Code 96 after wiping the memory. Checked wires on secondary circuit. In the process of replacing the EEC relay. All wires on relay read battery/alternator voltage as they should and Pin 19 reads the same so I am unsure what is causing the problem. The tan/green wire that goes to Pin 22 is reading 1.40 volts at the fuel pump relay and 1.15 volts at ECU Pin number 22 ... this doesn't seem right from what I have read. Also, the car...

Referenced these as jrichker always had the goods on this stuff.

LILCBRA · Dec 13, 2024

Rdub6 said:
I’ve always had trouble with the hose on those pumps curling up, and then they’re not getting to the bottom of the tank. Anybody have any tricks that worked to get that hose all the way to the bottom?

Not really - I just tried to make sure that the natural curl of the hose ended up pointing down as best I could before I tried using the pump.

General karthief · Dec 13, 2024

Lay the hose in the sun for a while, I zip tie a big bolt to the end of the hose and hang it in the sun, usually gets them straight enough to work with.

gkomo · Dec 13, 2024

Could it be the switch got triggered like if you got rear ended? The one on the inside up behind the taillights? I remember I was parallel parked overnight once and tried to start my mustang the next morning and it just kept cranking and cranking, finally figured out the car behind me must’ve bumped me trying to get out and triggered that switch.

Help! Fuel pump not turning on.

New Member

I wish I didn't have all of these balls in the air

I wish I didn't have all of these balls in the air

New Member

I wish I didn't have all of these balls in the air

New Member

New Member

New Member

So while I wait to figure out my rear end issues

lube between the nut and the face. I know my lubes

Engine Post in thread 'Intermittent CEL with loss of power'

New Member

New Member

New Member

Engine Post in thread 'Intermittent CEL with loss of power'

New Member

lube between the nut and the face. I know my lubes

I wish I didn't have all of these balls in the air

wonder how much it would cost to ship you a pair

now i can hopefully expect to receive the shaft

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