So here is the deal my truck won't start. It's acting like shes not getting enough fuel. The motor turns over but will not fire. I drove it to school and back no problem. Then while at home I couldn't get it to start. Its done this 3-4 times before and has started after half an hour or so, until today where it will not start 5 hours later. I changed the fuel filter today and there was no pressure in the lines which makes me think its a fuel pump or the relay switch.

My truck is a 1999 F-150 5.4L, 139" wheel base, and the vin number is 2FTR18L8XCA16828 with close to 100,000 miles.

When I turned the key to the point just before the truck usually starts, I hear the fuel pump make some noise but still doesn't start.

I pulled the wiring harness to see if any juice was going to the tank and the only thing that had current was a single wire, just for a second.

I'm going to buy the relay switch for $15 tomorrow and see if that fixes the problem. If not, I have to spend $250 for a fuel pump that won't come in until Wed.

If anyone knows where this switch is located, please let me know. I am assuming that this is different than the fuel pump shut off switch which is located on the passengers side, up by where my right foot would rest.

Any help would be appreciated.

And yes, I have a full tank of gas.

 

Before buying a fuel pump you might check out the IAC valve. I just had the same problem you described with my 2000 5.4L F150. It would turn over, but would not start. There are lots of posts about the IAC valve and this problem, check some of them out to see if it sounds familiar.

Scott

 

The IAC valve seems more of a problem after the truck is running, am I correct?

I found a pretty good article which will guide me tomorrow when I run through my truck again.

 

Based on that VIN #, the problem is obvious....just kidding

The first thing you should test is the fuel pressure at the fuel rail during various conditions.

 

Check the fuel pressure at the fuel rail. If you don't have a fuel pressure gauge, turn the key to the position just before start. The fuel pump should come on for a few seconds and then shut off. All the above suggestions are good things to check.

Without a fuel pressure gauge it'll be hard to trouble shoot.

I would replace the fuel filter while you're looking for the problem.

 

I knew the VIN number was a dead giveaway.

I replaced the fuel filter after trying to start the truck a few times. There was no pressure in the lines. I can try pulling off one of the lines then turing the truck over to see if any fuel comes out.

I hear the pump turn on for a fraction of a second. I never paid any attention to the noise before this started to happen so I can't really tell what the deal is.

 

Buy a fuel pressure gauge. It's safer than having an open line with fuel coming out and will tell you more about where the problem is. I can't remember what I paid for mine, but I believe it was under $20.

When you turn the key to the on position, you should hear the pump run for a few seconds then shutoff. If not, on the fuel rail is a relief to bleed off the pressure. Relief the pressure and turn the key on. If the pump comes on and then shuts off, then the fuel pump is making the required pressure. If it never comes on, then check the relay.

 

Fuel pressure guages run about $40.

The pump should run for about two seconds when the ignition is first switched from OFF to RUN. You can listen for it to see if it is audible.

Steve

 

The bad IAC valve on my truck caused the truck to not start. I know some trucks will start and run rough with a bad one, but in my case it would not even start. I did not even get any warning signs, it just would not start one day. It would turn over and get very close, but would not run.

If your fuel system checks out ok, this would be another possibility.

 

To test for an IAC fault causing a "no start" condition, just press the throttle 1/4 way while attempting to start.

If it then starts, the IAC is stuck closed.

Steve

 

I put a new fuel pump in yesterday and it still wouldn't start. The truck was doing the exact same thing. So I pushed it out of our shop so a tow truck could pick it up today but low and behold, went out to start her just for the hell of it, and she ran like a champ.

I don't think its the IAC because I tried giving it a little gas when it wouldn't start. I will most likely end up buying a fuel pressure test kit and a new relay switch tomorrow just for the hell of it.

If anyone knows where the fuel pump relay switch is located, please let me know.

Thanks

 

Interesting. Take a look at my message "Starting Problem", from Logman. Have you tried turning on the key to see how long your pump runs? On mine, the truck will not start and there is no spark until the pump shuts off, which could be anywhere from 2 sec to 5 min. Once the pump shuts off, away she goes.

 

I would definitely try a new relay. Reason being that the pump is turning on for a fraction of a second, as in the relay is switching, but not holding. You should have tried that first since it's a 10 dollar part. It could be a couple different relays actually, if the ecm relay is bad, it would do the same thing. You can test the relay by using jumper wires and your battery by making a complete circuit on the primary side of the relay.

I have not had to mess with the ones in my f-150, so I don't know exactly where they are, but I'm guessing it's similar to my ranger which has a black box on the drivers side. Pop the top off and there they are. Your owners manual will tell you which one is which if the top of the box doesn't.

Has it ever quit while already running? My ranger was doing this for a while, 'till it wouldn't start at all. After 3 days of f'ing with it, I ended up finding a loose fuse. By accident I left the key on and pushed on the fuse box and heard the pump fire up.

 

I checked all my fuses and they are still intact and tight. I figured it wasn't the relay because the pump was getting power. I figured either the pump would get power, or it wouldn't. I didn't know there was a middle ground.

I got the truck started this moring and drove it to the local automotive repare shop. Little bastards got it to start EVERY SINGLE TIME today. The owner said they started it around 20 times or so. I even started it myself twice after work.

And no, the truck has never cut out on me while running. Drives like a champ once shes started.

 

Today I tried swapping the relays around and still no luck. The truck started fine for the past week or so but Christmas Eve Day the truck would not start. I finally got it started late on Christmas Day and it ran fine but will not start today. Does anyone have an idea what it could be?