Is my fuel pump dead?

[Austin96]

93 Mazda Navajo
237,000 miles. Always engine runs like a sewing machine. Smoothly. In south Fl it's been hot where the real feel the past 2 months is between 100* - 110* F each day. So after a 2 hour drive on errands yesterday I am at a light and engine shuts off like I ran out of gas. (I was low but about little above an 1/8th of a tank.)
Truck would not start back up. I thought maybe cat was clogged as this once happened to me with an old Celica and after like 20 minute rest it started back up, but it has not started at all. Just cranks like out of gas still. Will not start.
Checked the fuel pump fuses and relay and it's neither. Wires and plugs are fairly new. I put the ignition on accessory and listened with my ear to the open fuel door and did not hear any humm or clicks so I figure my fuel pump died. Is there any other way to diagnose if it's my pump other than what I've done so far?

I am considering doing the "Burns" fuel pump surgery from above http://www.explorerforum.com/forums...t-gen-gas-tank-fuel-pump-access-panel.182160/
but I don't want to go through this and find my pump was still good.

Thanks.....

 

[92exp4x4]

There is a port on the fuel rail for checking pressure. It's on the pass side of the upper intake. It looks like a tire valve. Push it in and if you have pressure, chances are something else is going on. If not, verify the electrical side. After that, you gonna need a pump.

The computer turns on the pump by grounding the fuel pump relay. The relay in turn, supplies the pump with power. The ground for the pump ties into the harness and goes to the frame eventually.

Male sure your relay is good.

 

[Austin96]

There is a port on the fuel rail for checking pressure. It's on the pass side of the upper intake. It looks like a tire valve. Push it in and if you have pressure, chances are something else is going on. If not, verify the electrical side. After that, you gonna need a pump.

The computer turns on the pump by grounding the fuel pump relay. The relay in turn, supplies the pump with power. The ground for the pump ties into the harness and goes to the frame eventually.

Male sure your relay is good.

I found this website link http://troubleshootmyvehicle.com/ford/4.0L/how-to-test-the-fuel-pump-2
going by what you suggested. I do not have a fuel pressure gauge but will try parts store asap.
Thanks. Austin

 

[92exp4x4]

You dont have too, but it's not a bad idea to hook up a gauge. Normal fuel pressure should be about 35-40 psi.

 

[2stroke]

First things first, did you add some gas? Trusting your fuel gauge that much is the last thing I would do. Next up is the fuel pump inertia switch. The things are notoriously touchy. Many good fuel pumps were replaced because Ford was stupid enough to put them where they did. Then swap relays around and see if you have fuel pressure to the fuel rail. You don't need a gauge, you can just push the pin in after turning the key on. You will know right away if it has fuel pressure or not.

 

[Austin96]

There is a port on the fuel rail for checking pressure. It's on the pass side of the upper intake. It looks like a tire valve. Push it in and if you have pressure, chances are something else is going on. If not, verify the electrical side. After that, you gonna need a pump.

The computer turns on the pump by grounding the fuel pump relay. The relay in turn, supplies the pump with power. The ground for the pump ties into the harness and goes to the frame eventually.

Male sure your relay is good.

Does the ignition need to be on as in trying to start the truck while the pin inside the valve is being pushed in at the same time?
Also I have the cap off and there's not much room to use a screwdriver head or even a tire prissure gauge to push that pin in.
Tried both and there is a thick harness blocking the front of this pin like an inch and a half in front of it.

 

[natenkiki2004]

Cycle the key on, wait a few seconds, off, then on again for a few seconds then off. That will attempt to build pressure. From there, I like to use the short end of a small allen wrench to push the pin in on the schrader valve on the fuel rail. You should have a short, quick spray come out. It won't last long because there's not much volume, just a bit of pressure.

 

[Austin96]

Cycle the key on, wait a few seconds, off, then on again for a few seconds then off. That will attempt to build pressure. From there, I like to use the short end of a small allen wrench to push the pin in on the schrader valve on the fuel rail. You should have a short, quick spray come out. It won't last long because there's not much volume, just a bit of pressure.

Good tool to use. OK so I push in the pin prior to ignition and did get a little squirt of fuel spit out. Then I try again with cycling the key a few times and nothing came out. I tried this a few times. Nothing.
Two Advance stores near me neither one has a fuel pressure gauge to loan & wasnt going to buy one for $50. I ran into a mobile mechanic who will come out and test things for free. If it's the pump he does cut the hole which I was not keen on doing in my garage or driveway myself. So maybe save a few $$

 

[2stroke]

Have you checked the inertia switch, swapped relays, and added a few gallons of gas?

 

[malohnes]

Cutting the panel is much easier than dropping the tank.
2stroke's suggestions are very logical and simple.

 

[trashtruck]

at the rear of the vehicle, on the driver side frame rail is the electrical connection for the pump. it has 4 wires. 2 for the pump and 2 for the sending unit. the 2 wires for the pump should be thicker than the other 2. connect the pump wires directly to a battery with jumper wires and listen for the pump. if you can't hear it, it's probably time to replace it.

 

[Austin96]

Have you checked the inertia switch, swapped relays, and added a few gallons of gas?

Yes both. and the relay swap and fuse.

 

[Austin96]

at the rear of the vehicle, on the driver side frame rail is the electrical connection for the pump. it has 4 wires. 2 for the pump and 2 for the sending unit. the 2 wires for the pump should be thicker than the other 2. connect the pump wires directly to a battery with jumper wires and listen for the pump. if you can't hear it, it's probably time to replace it.

Cannot see that on my Nav. Any particular spot or a reference picture?

 

[92exp4x4]

Cannot see that on my Nav. Any particular spot or a reference picture?

It may be hidden behind the tank. Do you have a meter or test light?

 

[2stroke]

The connector is stuffed up on the drivers side in the frame rail. It should be pinned near the brake line. You can use a test light or multi meter. The only way to test is to jumper the relay so its always on with the fuel pump plug un-plugged. Then test for voltage. If you have over 12 volts, then pull the relay jumper and test the ground. You need a multi meter, and switch to ohms. From the thick black wire to a clean spot on the frame (use sandpaper to clean the rust off) you should see something really low like 0.2 ohms. If the ground is good and you have voltage (but no fuel pump) Then either you have a bad fuel pump, or a bad electrical plug (very small chance the wires from the plug to the fuel pump are bad). There are 2 ways to test the electrical plug itself, and the best in your situation is to actually stab the wires with a sharpened nail on the pump side of the plug. If you measure from the pump power to a clean frame and get a low voltage, you have a bad plug. You can verify by checking from the ground wire to the same spot on the frame. Alternatively you can check ohms across the plug by using 2 nails both in the same wire, but on opposite sides of the plug. If you have good power and ground on both sides of the plug, your pump is most likely bad.

 

[Austin96]

Will look for that box witht he 4 connections again Saturday. I looked and the mobile mechanic also looked. Neither of us saw it.
Got the seat out and pretty much know where to cut metal for pump access. I can get my hand along the 2 fuel lines actually on to the top of the tank and touch the top of the fuel pump with my hand so I know where it is underneath. Has anyone mentioned how lame it was for Ford to not put in an access cover to the pump??

 

[2stroke]

Its not a box, its a round plug. Its black, 4 wires, about 3" long, and pinned right to the frame. The brake line and ABS wires are by it, but its the only plug back there. It is in the frame rail right by the gas tank.

I blame Ford for a lot of things, but you can't really blame them for not adding a fuel pump door. Very few cars ever had them, and I doubt any had them in over 30 years. I think the location of the fuel pump is fantastic. Its not hard to cut your own door, and its nice and hidden under the rear seats.

 

[PVTJames]

I replaced my whole sending unit and I didn't think dropping the tank was that bad. I removed the shielding an had the job done in an hour or less. (this was in my driveway not on a lift)... 94 explorer 4x4 xlt

 

[92exp4x4]

They aren't bad to drop, it's just when they fail with a full tank that it's more difficult. The skid plate makes a great place to support it with a jack.

Just jack up the truck as high as you can, support with stands and drop the tank. I think there is like 5 bolts? Its not bad. The worst part is separating the lines from the pump.

 

[Austin96]

Update for my '93 Navajo. ( OP) removed the back seats on both sides. pulled back carpet and removed the black plastic seat support. ( 2 screws) In my Nav there is already a rubber plug in the center of the floor so I pulled it out to get an idea of the thickness of the floor metal. Not thick at all. I estimated the pump location but to get it exact I slowly drilled a 1/4" hole in the vicinity, then slowly drilled it larger with a wider Wing-It's bit I had for doing tile. From there I could see with my phone flashlight the whole top of the fuel pump. This was good because my estimate was off by the size of the pump.
Home Depot sells Aviation Snips for $14. which cut the steel pretty easily. Not totally clean like a sawzall but to me safer. I can clean up the edges with the Snips and a flat plier.

Next up is figure out what I need to remove the fuel hoses and the pump housing.
AA