I know how the title sounds.

I've been running into an issue for the past few weeks where I've stopped off at a gas station for a pack of smokes or something on my way home from work and the truck will not start back up. The truck will be running fine but will not start after I get back in it just doesn't turn on. In two of the three or so times this has happened a few guys have helped me push it to a gas pump, I'll put gas in it, and it will fire right back up no problem. Last Wednesday night, for instance, it died at the gas station by my house, I walked home, got my gas can, walked back, put in even less than a gallon, maybe like a 1/4 and it fired right back up; it didn't take a lot of cranking or anything, just poured gas in and it fired right up.

Backing up a bit, this mobile mechanic replaced the fuel pump a few months ago and the level has never read correctly since, it will not go over a half a tank regardless of how much gas I put in it. Given that, I put gas daily and more than enough for the trip to and from work but this whole deal of not starting without pouring gas in there is definitely a new thing.

Does anyone with any understanding of the fuel system of this vehicle know what might be going on? It just seems weird that it'll crank and crank and crank and then I put a splash of gas in there and it turns right on like nothing happened; it doesn't take a deal of cranking or anything like as if it had no fuel in the lines, just fires right up after a splash of gas. Today I tried to turn it on on my lunch break and nothing; I put gas in it from a can we had here and it fired right up.

 

When you open the gas cap do you hear a rush of air into the tank?
Maybe your EVAP vent system is bad so you are building up too much negative pressure in the tank when driving
Next time don't add gas just open the gas cap and see if it starts OK

Watch the CEL(check engine light)
CEL comes on with key on, means computer has booted up OK
CEL should go OFF as soon as engine starts to spin from starter motor, that means computer is getting a good timing signal from crank sensor so will start spark and then 1 second later the fuel injectors will start opening
Engine will never start if CEL stays on while cranking

 

The CEL has been on ever since the guy replaced the fuel pump. The filler hose he described as "falling apart" and it is to the point of where if I set the fuel hose at the pump to fill I'll wind up with a puddle under the tank and you can see and smell fumes coming out near the fuel door so that triggered it I'm sure. As I'm not a rich man, I've just been driving it like this and just not filling it up too far and it's been working out fine barring it being a little fumey, but this has only recently started happening in the past few weeks.

 

Yes, CEL can be on when driving if there are codes set

But CEL will go off when cranking watch for that when it starts OK........... and then when it doesn't start

 

I see what you mean now. I will keep an eye out for that.

If the CEL stays on while cranking, I mean, any ideas there? The crank sensor? That kind of crossed my mind as well but it's just been a weird thing. I've asked mechanics here at work - we don't really work on Fords and not of this era, but they don't seem to have much of a direction to point me to other than it just being a problem with the fuel pump but dropping the tank or removing the bed isn't like small time stuff unfortunately so I guess I'd hope it'd be the crank sensor or something like that over a fuel pump problem.

 

Well adding gas to a tank that already has gas doesn't really change anything in the fuel system, so mechanics are right there is no "sense" in that part

Only changes are releasing pressure in the tank when cap is removed, or the TIME it takes to get and add the gas

Could be the new pump is overheating while its on, when you turn the engine off, it gets "heat soaked", too hot to restart until it cools down a bit
When you are driving the gas sloshes around the pump drawing away excess heat
When you stop and shut off engine, hot pump warms up the fuel around it so no cooling effect, "heat soak"
Add fresh "cooler" gas.........pump can start
Long SHOT

Fuel pumps are NOT quiet
When you turn the key on Listen
Should HEAR the pump in the tank run for 2 seconds, then it shuts off
Repeat key off and then on and listen
Do this until you KNOW what it sounds like when its working
When there is a No Start.............listen, key off/key on..........listen

 

So I tried starting it without adding gas and with just opening the cap and even after some time it didn't make much difference.

I've had the vehicle looked at by our shop foreman now and he couldn't replicate the condition and it started every time he tried cranking it; he had put a pressure gauge on the fuel rail and it looked fine. That was Wednesday, he was off yesterday so I attempted to start it while it was in the lot and it started just fine a number of times once again.

I then let it run for like 30 minute out in the parking lot, turned it off, and then it would not turn back on. The pressure gauge read about 15psi and dropped further and further as I tried cranking it a little more. Just for the sake of it I tried the 50/50 test I'd seen you mention in other forum posts and it did start with the starting fluid - obviously did not run, but it did try to start on the ether.

I also pulled the check engine codes which are P0118 and P0340. I read elsewhere online that the coolant temp sensor can cause a no start condition, but considering there is no fuel pressure at the rail I don't think that either of these would be the culprit here.

Fuel pressure regulator possible? I am toying with the idea of even just checking the fuel filter. I replaced that last year in September, but I'm just hoping it's something other than the fuel pump and the fact that it only happens in the heat really has me wondering.

Any help is appreciated

 

Do you HEAR the fuel pump run, for the 2 seconds with key on?

15psi was enough for engine to start, and means Fuel Pressure Regulator is holding pressure
Yes, if you don't turn the key off and back on between cranking the fuel pressure will just continue to drop each time you crank the engine

Key on/off = fuel pump on for 2 seconds which gets about 10psi fuel pressure, each time, so 3 key on and off = 30psi
Cranking = no fuel pump on
Engine RPMs above 400 = fuel pump on full time
Cranking speed is 200rpm


Fuel tank-Fuel pump-->>--filter--------->>----------fuel rail/injectors----->>-----fuel pressure regulator-------->>-------Fuel Tank

 

Yeah I'm hearing the fuel pump engage but turning the key after it's run out of fuel pressure doesn't seem to do anything.

From the last point you make there "fuel tank-fuel pump etc" I guess I can infer that it's likely not the regulator if that comes after the fuel rail in the system.

Just don't know where else to turn with this other than the pump itself

 

Try pushing gas pedal down to the floor when there is a no start
Hold it down all the way and crank engine over, this is called "Clear Flooded Engine" mode, all engine computers have this, not a Ford thing

At 0 RPMs and throttle at Wide Open Throttle(pedal to the floor) the computer will turn OFF fuel injectors, so you can crank the engine and the in coming air will "dry out" the intake and cylinders
You can release the gas pedal at anytime, even while cranking, and computer will start opening injectors again

I use this every morning on my 400+k 4.0l to pump oil thru the engine BEFORE starting
You are doing it to see if hot engine may be flooding out