'93 Exploerer XLT - Fuel Line Problems

This all began a week ago.

I was in a parking lot about to drive home when my '93 XLT acted like it was out of gas. The gas gauge has never worked since I got her so my mileage available is usually a matter of odometer reading and math. According to that, I still had at least 50 miles left...

I got a can and added roughly a gallon and a half. After some engine spinning, she cranked and took me home, which was about a block away. The next morning however, she did the same thing... and so did I by adding more gas. I also injected the throttle body with gas directly and she cranked but would not stay running.

A few days ago, I installed a new fuel filter. She started right up and ran great for three days and then... she went down again and had to be wreckered home.

On a sidenote, the old filter contained some really dark, goopy stuff. More than one article I've read suggested that my older Explorer has a tank with some kind of rubber coating within and that the ethanol in gas today can cause that to dissolve and cause major problems.

Of course, there's also memories of how kids used to drop M&Ms in gas tanks as a very unfunny joke ('60s and '70s), which almost immediately shut 'em down. Living in a college town today... wondering if this is still practiced, lol.

So, this is where I am now, trying to figure what to do next...
- I can buy a used gas tank w/fuel pump from a very respectable Ford wrecking yard for about $80. (With another $130, it can be installed in about 90 minutes.)
-I can acquire a new fuel pump full assembly for roughly $135
-I can buy just a fuel pump by itself for about $70.

I'm open to ideas and suggestions... would sure appreciate any at all.

Thanks,

Mike
aka OldChrome

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Rent a fuel pressure gauge from Advanced or NAPA (you get all your money back when you return it).

Check fuel pressure at idle and 2500 RPM. They have a push button and a plastic hose that relieves the fuel pressure and drains the gas in the gauge lines before you disconnect the gauge.

You can see the color of the gas in the clear drain line when you relieve the pressure. Check to see if it's clear, rusty looking, dark, etc. That will tell you if your injectors (and engine) are getting clean gas as it's post fuel pump strainer and fuel filter.

You might have water in the tank. If it's not too much you can buy a bottle of HEET and throw it in the tank.

I wouldn't go buying new fuel tanks and fuel pumps until you've done more troubleshooting.

mekelly - Thanks for the reply.

I'm getting zero gas pressure in the line coming up to the engine.
I'm going to cycle back now to the filter and see if the incoming line there is getting any.

Thanks for the reply

Mike

Is the pump priming when you turn the key on (engine off)?

Also, make sure it's not your fuel pump relay OR your EEC relay. With a bad fuel pump relay, you'll get no fuel, with a bad EEC relay you get no spark and no fuel!

When you first turn your key on (engine off), your 'check engine' light should come on (assuming no burned out bulb). If it doesn't you probably have an EEC relay that isn't energizing.

I went through 2 weeks of troubleshooting a crank-no start condition and after replacing the fuel pump, fuel pump relay and fuel filter, what I needed was a new EEC relay!

However, given the pump was 21 years old, I didn't mind changing it.

Just went to AZ and got a $12 Fuel Pump Relay Switch... basically a 5-prong plug that goes in the fuse panel under the hood. I turned the key to ON, could actually hear the fuel pump as it pressurized the line and it turned right over.

New problem - I don't know now whether to be happy or worried.
Oh well... only one way to find out. Time to take her out for a spin...

EDIT:
Was typing this as you were noting the exact same item.

It seems to have worked. Going to take her out for a run a little later so that if she goes down again, I can get a tow home from my neighbor and not have to call a wrecker.

EDIT 2:

What's the EEC?

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Those relays can fail intermittently over time. Mine would fail after getting heated up by driving 5-10 minutes.

All those relays are the same (at least in my 1994) so you can switch them around for testing.

I went ahead and replaced both the fuel pump and EEC relays for good measure. Haven't had a problem since!

What's the EEC?

Electronic Engine Control module (some people call it the PCM, Powertrain Control Module). Basically the 'brains' of the car that takes all of the sensor readings and adjusts fuel/air mixture, timing, spark, etc.

Without that, the car obviously won't run. That's why the relay that supply's power to the EEC (it's next to the fuel pump relay) can be tricky. The car will crank (turn over) as the starter still works, but the EEC won't command any spark to be produced and won't energize the fuel pump (among other things). So you get a car that cranks and cranks but will never start.

Thanks... getting to know even an older model with all the electronics is something of a pain at times.

My first car was a 1968 Ford Fairliane 500 3-speed (column) 2dr with a 289cid. I got it when I was in the Army stationed at Fort Gordon in Augusta in the early '70s. Had just under 60,000 miles... loved that thing.

After my first wife and I split, I cut a whole in the hump and installed a Fenton 500 shifter. Someday, I'm gonna find one and restore it to cherry condition.

Thanks again for all the help and advice!

PS - My brother was a cop in Marietta back in the late '60s.

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No problem, thanks!

I once had an interemittent fault in the fuel pump circuit. It was kind of frustrating (as most intermittents are). I was finally able to trace the fault to a break somewhere in between the fuel pump fuse and the fuel pump relay. Cut that wire out and spliced in a new wire and that problem was solved.

How good are you with DC circuits? I know we talk about "all the electronics" in cars, but the fuel pump circuit (outside of the PCM) is a fairly straightforward DC circuit. I found mine by 1) getting a wiring diagram out of Chiltons (even that one was good enough) and a voltmeter. 2) Then, starting at the battery, measure the voltage at key points in the fuel pump circuit (battery, fuse, relay, inertia switch, tank). 3) To test points downstream from the relay, you will need to manually close the relay using the "fuel pump test lead" in the self-test connector.

Your fault lies between the last point where you have 12 V and the first point where you don't (The PCM generates a 6-7 V "ghost" voltage that shows up in the fuel pump circuit. Don't let that confuse you).

The frustrating part -- being intermittent, you have to wait until the fault manifests before you can do this. If it fixes itself while you are testing, you have to wait again.

It was mentioned but what am I looking for if the fuel pump primes and engine starts but dies out after running a few seconds?

What are you getting for fuel pressure?

Fuel Pressure

That is a very good question. Because it started several times then starved out in around the same time frame I have been looking for something that indicated to the fuel system the engine was not starting and the fuel pump was not reactivated. Thank you for a starting point. I'll get on it in the morning. It may make no difference but when this started it had been running around 15 to twenty minutes then just died.

FF/EMT
Larry

15-20 is WAY too low no matter what. Off the top of my head, I think you want 35-40.

Sorry, last time started it was running fine for 15 to 20 minutes then just died. Sense then it starts but runs out of fuel after burning through what is primed when the ignition is turned on. I'm working on getting the fuel pressure readings today. Thank you for the reply.

Larry

I had to buy a tester but you were right. I'm not getting a reading at all. I checked power at the inertia switch and got 6 volts on both sides. I have replaced both relays a while back and it started and ran fine until this last time when it started and ran for a while then died.
Thank you for your help this far
Larry

What kind of relays did you use? The cheap ones may not last under a duty cycle like the fuel pump requires.

Didn't think they were cheap. Carquest over the counter from a good parts house. Thank you for the idea as a bad relay kinda makes sense. Someone mentioned a ghost voltage of 6 to 7 amps generated from the ECU. That would not make sense unless the normal circuit was dead. I'll replace them again with heavy duty and hope for the best.
Larry

Buy the best you can, I'd be tempted to even get some from a Ford dealer. It's hard to beat the OEM relays and you definitely don't want to be stuck on the side of the road because your computer isn't getting power.