1998 Ford F-150, 4x4XLT, V-8, extended cab

Every few months, my F-150 refuses to start. Amazingly, the truck decides to start several hours later.
- At first, I thought my 8 year old battery was weak and not energizing a relay, so I replaced the battery. The problem persists.
- A couple months ago, I checked all the fuses and checked the electrical connections. No open circuits or corroded wires.
- I've tried switching the ignition on/off several times, in case the fuel pump is weak and needs a little prime.
The problem seems to occur after wet weather, whether it's rain or ice. I suspect it starts after something dries out.
I am contemplating taking it to the dealer...
Is something on this truck notorious for causing these symptoms, as I would prefer to avoid a dealer charge?
Thanks.

 

Have you tried giving the starter a solid wack? If it's original it may be time.

 

Nope, I have not tried hitting the starter. The engine turns over fine...it just won't fire, so would you suspect the starter? The battery has plenty of juice. I tried jump starting it tonight with no success...that is until I walked away for 30 minutes. When I returned, it started fine, and this was without a jump start.

Tonight was probably the 3rd time that it started after walking away for ~30 minutes. The air was still very damp, so I'm struggling now to believe something dried out this quick.

The truck runs fine for months, then decides to stop starting near a major wet weather event.

 

I'd start by checking the spark when it won't start. I'm not all that familiar with these years, but ignition is often the case generally.

If you have little or no spark, you could go backwards from there. The wet weather could be affecting either the high voltage or wiring/modules.

Maybe you can simulate things with a hose. Spray it up from underneath and onto the hood etc. You don't want to spray it directly into the engine compartment. Be careful when checking the spark if you do this.

BTW the reason somebody suggested the starter was that your original message wasn't clear as to what was happening. I also assumed that it wasn't cranking. Not trying to criticize, just my thought.

 

"Won't start" is not a specific enough description.

You need to specify more clearly:

1) No crank
2) Cranks but does not start.

or whatever.

 

Thanks for the feedback on my description, and I agree with the input. I hastily posted the message Friday night, while sitting at work waiting for a ride home, since my truck would not start. My frustration led to a hastily posted message.

Update:
- Friday morning, the symptoms changed to one click when I turned the ignition key. The engine would not crank and thus not start. Friday night, I traced the voltage from the battery to the starter and determined the fuse was okay, start relay was okay, battery was okay, wiring was okay, but the starter was bad. While unhooking the wires on the starter, I noticed the metal wire running from the solenoid to the starter was broken (wire had arced over time and welded itself in half). Replaced the starter, and the truck started fine over the holiday weekend and Tuesday. Thought I had my starting problem fixed...
- This morning, I went to start the truck, and the starter cranked the engine fine, but she won't start. Same symptoms as my previous post. It rained most of the day yesterday, and the humidity was 100% over night. I will try starting her again over lunch. If the previous symptoms hold, then the truck will start later today.

I'm contemplating installing a fuel pressure gauge on the engine, so I will know with certainty whether the engine is receiving fuel. If the problem would occur other than at a time when I need to go to work, then I would check for spark, too. (Typically, by the time I return home to check spark, the engine starts fine)

Any other ideas?

 

Another chapter...
Well, my prediction was wrong. The truck did not start after trying ~10 times from Wednesday AM to Thursday evening. Prior to replacing the defective starter over Labor Day weekend, the truck would successfully start approximately 30 minutes after an unsuccessful start. Since the symptoms changed this week, I checked the following again, and no problems were found:
- fuel pump fuses
- fuel pump relay
- emergency fuel cut-off switch
- battery voltage (roughly 12.5V at this point in time)

By depressing the schrader valve on the fuel rail with the key on, I determined no fuel was pumped to the engine. This led to numerous smacks of the fuel tank with a rubber mallet (as suggested in another post) with the key on...but no luck. Then, I disconnected the fuel line from the filter on the tank side, turned the key on, smacked the tank some more, but no fuel.

I was nearly convinced the fuel pump was my problem, but I really wanted to start the truck one time, so I could pull it into the garage to change the pump (I have a significant hill to climb when entering my garage, so pushing the truck is not an option).

My last resort was to charge the battery, as this worked when I had an 8 year old battery installed in the truck last year. After my battery reached ~14.55V (this battery was new, as of this spring), I tried the shrader valve again with the key on, and fuel sprayed from the valve!! I cranked the motor and it started immediately.

After letting the engine run for ~10 minutes, the voltage dropped to 14.22V.
Increased rpm to 2K, and the voltage increased to 14.3V.
Another 10 minutes of idle, and the voltage dropped to 14.17V.
Turned the key off, and voltage dropped to 13.30V.

Based on this result, I'm wondering if my problem is due to an electrical component which requires ~14V or more (fuel relay, fuel pump??), my new battery, my 11 year old alternator, or some other source? I hesitate to change the pump now, since it works with ~14V.

Any suggestions on further diagnosis?

 

Have you treid changing the fuel filter?

you no them things can be bad , some times it lets fuel through other times it dont , maby its old and gummed up , so hit bumps and sometimes it works some times not.

i would start thier, as that can act like a bad fuel pump as well , also check the safty fuel shut off switch, make sure its not off.

 

I have the same symptoms approximately once every two years. Damp weather, 4.6L engine cranks fine but won't start. Get a ride and return with tools but it then starts without touching a thing.

Did you ever figure it out?

 

Yes, I eventually stopped the problem by replacing the fuel pump. You can read the saga at:

https://www.ford-trucks.com/forums/8...ermittent.html

Maybe this will help you.

 

I have the same issue. On days where the humidity is near 100%, no fire. Starter cranks.
New fuel pump
new plugs and wires


Does the fuel pump have some sort of controller? is that getting damp or wet?


thanks


1998 4.6 auto

 

I had same problem , replaced fuel pump$140ish ,fuel pressure regulator$55 then cam position sensor $30 but came down to cranck shaft position sensor, $30 part 10 seconds to change if you didn't have to remove ac, around $250 of throwing parts at the problem sounds cheaper than mechanic n u get your hands dirty, wish I started at the cheaper end n wouldntv spent $ on fuel pump

 

thanks. found one for forty bucks.