2001 Ranger, 108,000 miles, good regular maintenance per the Ford Schedule. 4.0L manual trans.

I changed the fuel filter 20,000 miles ago. This has been a recurring issue anytime my fuel level was low, about 1/4 tank or less, and when the truck was warmed up, hot. The fix in the past was to add fuel and let the truck sit for awhile. Now, today I drove home for lunch and when I tried to start the truck to return to work, it wouldn't start. Same conditions, low fuel level and it was warmed up. The engine will turn over and start to run with ether in the air box, so it's definitely fuel related. A fuel pressure gauge on the Schrader valve got a zero reading, not even a flicker, and no residual pressure after shut off.

Could this be only a fuel pressure regulator issue? Or should I prepare to replace the fuel pump? Is there a fuse that might be blown?

Please don't suggest the inertia button.

Any ideas welcome, any similar issues and their solution would be the best response.

 

I hate to say it, but an uncooperative fuel pump when warm/hot is usually a sign that it's on the way out. But there are still things you can do that won't cost you anything but a little time.

I assume from your comment that you checked the inertia switch. If so, how did you check it?

If you had a fuse that was blown, the problem wouldn't be intermittent. A bad relay could be intermittent. If you don't have the owner's manual, download it and find where the relays are. The fuel pump relay should be the same as another relay in the relay panel. Try swapping the fuel pump relay with another relay that you know works. If the problem follows the relay, you have your answer, but being an intermittent problem, it might take some time to show up. If the fuel pump relay isn't the same as another in the relay panel, give the fuel pump relay a tap while trying to start. That would help if the relay were sticky. If the contact is bad, it might not help.

Another check would be to smack the bottom of the fuel tank with a hammer while trying to start it. It's not uncommon for electric motors to get a bad spot and they need a little help to get started.

Since this happens when the fuel is low, I'm wondering if the nose is pointed downhill when you park it. My '98 Explorer will not start if I point the nose downhill when there's a little more than 1/4 tank. This is a common feature with Explorers and your Ranger might have the same feature. The way to confirm this is to turn the key to RUN (not START) and listen for the fuel pump. If it's turning, then the low fuel is the issue. You might need two people for this - one to turn the key and one to listen near the fuel tank. You shouldn't run the pump dry too many times, it's not good for it.

Do you have a wiring diagram? If so, locate the ground for the fuel pump. Remove the ground and clean it, even if it looks OK. Don't just look at it.

You could also try disconnecting and reconnecting any connectors in the circuit. Take a look at both of the connectors and look for anything unusual. Corrosion builds up on the pins and sockets over time and taking the connector apart will help to remove the corrosion. I haven't fixed a fuel pump with this, but I have gotten the A/C working on two different Fords by doing this.

 

A word of advice when whacking the bottom of the fuel tank. Hold a short piece of wood, 1 x 6 board about 10" long would work fine, against the bottom of the tank and strike that with your hammer. A acquaintance of mine poked a hole in the bottom of his tank with the head of the hammer. That all being said, the trick often time does work for the reasons pointed out by Mikeman.

 

^+2, I like the above ideas & yes don't strike the fuel tank directly with a hammer, you could use the heel of your hand, or heel side of your balled up fist, to thump the bottom of the tank to see if you can wake the fuel pump up if you find its not running when hot.

We only have 12 volts to work with, so I agree the whole fuel pump electrical system, including the fuel pump, belong on your suspect list.

Our power relays are a known problem part & heat often plays a part in their acting out, as Mikeman has suggested, so maybe also consider changing out the fuel pump power relay for a like known good one, not needed to run the engine, like the AC power relay & see if it'll make a difference.

I agree, with it starting if you added gas to the tank in the past, suggests a pump problem that was maybe fixed by cooling it down some with the added gas, but you may also have a voltage drop problem to the pump & if so, that needs to be found & fixed before replacing the pump, lest the new one fail prematurely because of voltage drop to it, as that voltage drop causes the pump to pull more current when running & that'll make it overheat, all a vicious circle. So, perform some voltage drop tests on the fuel pump circuit & the in cabin inertia switch location is an easy to get at spot to begin your test, as it gets most of the pump circuit electrical feed components & wiring tested when the pump runs. If voltage drop looks ok at the inertia switch, put the wiring between the inertia switch & the fuel tank, the tank electrical connector contacts, the fuel pump itself & its ground connection as Mikeman has suggested, higher up on your suspect list.
Here is a link to voltage drop testing with your multimeter if your not familiar with doing it. http://aa1car.com/library/voltage_dr...op_testing.htm

We are cautioned not to run the tank below 1/4 remaining, because the fuel pump is immersed in the gas to keep it cool in hot weather, so we should refill at the 1/4 remaining level, to keep our fuel pump cool & happy.

Seeing as how this seems to be aggravated by less than 1/4 tank of fuel remaining, maybe the fuel sender isn't indicating correctly & you really have less in the tank than indicated. So, if you suspect that, seeing as how Techron says it can clean corrosion off our fuel tank sender to wake it up & indicate correctly, maybe consider adding one 20oz container of Techron Concentrate Plus to the tank at the pump before filling, to get good mixing & fill with Chevron, Texaco, CalTex, or now Shell, all of which also have PEA in their fuel ad pack, so it'll raise the treat rate 10X above pump gas alone & can tidy up the fuel tank sender electrical connection corrosion & also tidy up the fuel injectors, intake valves, piston crowns & combustion chamber, so you can get other benefits for your Techron investment, even if sender corrosion isn't a problem.

More thoughts for consideration. Let us know how your trouble shoot goes.

 

Thanks Dan and pawpaw for the advice about exercising care when hitting the tank with the hammer. I sometimes forget that things are open to interpretation. Just a little bump is usually all it takes.

Regarding the comment about Techron, it's been known to help alleviate fuel indication problems with Corvettes. Forgive me for talking about that other brand.

 

Yup, Techron Concentrate Plus cleaned the combustion chamber & stopped my 4.0L CCDI marble noise.

 

If you look up the price for a fuel pump, 9H307, it runs around 500.00.
So if you have to replace one every 108,000 miles it works out to around
a half penny per mile. That's how I justify it in my mind, but it still hurts all at once.

Service advisor allowed me to point out that the fuel filter didn't need to be replaced at 81.00 because I had replaced the fuel filter just 20,000 miles ago. He then said that they change them every 15,000 miles. My response was the vulgar form of cow flop!
Because if the interval was 15,000 miles I would have changed it already so I knew he was wrong. I looked it up when I got home and the interval is 60,000 miles. So that 81 dollar job should be good until 140,000 miles.

 

I got the used fuel pump replaced today.
Brought the old one home in the bed of the truck.
I put 12V to it on the bench and it was locked up tight.
Tapped on it a couple of times and it spins like a top now.
Now I've got a spare fuel pump.
Interesting info was found out, my 2001 4.0L manual trans regular cab was produced on 3-29-01, and put into service on 4-12-01.
I think it went to a NAPA dealer in CO. That's who I bought it from anyway.

 

OK, good feedback that replacing the fuel pump seems to have put the fix on things.
Good call on the fuel pump belonging at the top of the suspect list Mikeman.

 

g_k50 said: "Brought the old one home in the bed of the truck.
I put 12V to it on the bench and it was locked up tight.
Tapped on it a couple of times and it spins like a top now.
Now I've got a spare fuel pump."

You have a spare fuel pump ... that you cannot trust. I guess it would work in an emergency, but the same thing will likely happen again, as in it won't pump when you need it. If you take it apart, check the brushes and bearings, I think you'll find they are most likely worn out. When the brushes get worn, they have less spring pressure to hold them against the armature, so will have poorer conductivity and may not pass enough juice to get the pump moving from rest.
tom

 

I don't have to trust it, the person who buys it on Ebay has to trust it.

No, but seriously, (thanks for your thoughts tomw) a motor works until it doesn't. I haven't taken this Ford fuel pump motor apart but it looks similar to a Mercedes fuel pump that I did take apart. It's a precision made pump with close tolerances, I'm assuming that a piece of debris got thru the in tank strainer and lodged between the pump parts preventing the motor from spinning, tapping the motor dislodged the debris allowing the motor to spin. It's not the motor that's worn out it's the in tank strainer.

Obviously Ford likes to replace the whole assembly rather than call for an in tank strainer maintenance item.

 

If you do not have holes in the in-tank strainer, I'd bet the pump brushes are worn out. It runs the whole time the engine is running, and is cooled by 'return gas' (which just came from under the hood so 'cool' is questionable) unless it is a returnless system.
When they fail, they do just what yours is doing. Thump the bottom of the tank, and the brushes may jostle enough to make enough contact to power up the motor.
If the bearings are going bad, the armature can get a bit cocked, and difficult to spin unless whacked to again move the parts so they are free.
In all my time twisting wrenches, I have seen only one 'sock' that was plugged, and that was on a Pinto that could not climb the hill to the Caldecott Tunnel in the SF Bay Area. It would run fine and slowly start to lose power. I dropped the tank in my driveway, pulled the pickup (pump was on the side of the engine) and the sock was plugged with ???. Pulled the sock, and put a large semi-transparent filter under the hood, and off she went. My sister gave me the 5-gallon can I used to hold the fuel and I had it until a year or so ago.
tom

 

Thanks tomw, I think we can both agree that the motor for the fuel pump is a DC motor. In other words it's a direct current motor and doesn't need alternating current to make it rotate. So I think that the brushes have been eliminated because there's only need for one contact. The fuel is returned to the tank but it doesn't run back thru the pump to cool it, it drains back into the tank after going thru a check valve, which also looks like it's easily replaceable. If the bearings were bad it's possible that there would be radial movement in the motor axle, which I don't find. But again I haven't taken it apart.

 

Ummh, there are two brushes. Many if not most AC motors are brushless induction motors. The motor in my heat pump is induction as is the blower motor in the air handler, and the motors in the washer & the dryer. The motor in my electric drill & saw both have two brushes as they are not induction motors. So, I still vote for brush failure. One brush passes current through the commutator into a winding and back out through the commutator on the opposite side. Said current sets up a magnetic field opposite to the field in the surrounding permanent magnets. That makes the armature rotate. If the bearings are worn, or the brush springs extended as far as they go due to brush wear (or overheated springs that have lost their tension) you have two places where the current flow can be interrupted or impeded. Worn bearings can allow the armature to be offset such that one brush makes poor contact, or allows the armature to contact the inner side of the surrounding magnets. Regularly running the tank low on fuel, and I have no idea what regularly means, will deny any cooling from the pump being immersed in fuel. I likely mentioned returnless systems denying fuel flow over the pump, but after more brain neurons doing something, it seems a returnless system would only deny flowing possibly heated fuel over the pump, and only when the fuel level was below pump level.
Not sure what this all means, but if you do an 'amp draw' test, you may be able to determine the condition of an in-tank pump without having to go through the process of dropping the tank and removing the pump/sending unit.
tom

 

Ok, I stand corrected.
So if I replace the suspect used motor with a new motor, Bosch 69134, for example,
I should have a fuel pump assembly that is trustworthy.