Intermittent Fuel Pump Issue?

[kythri]

Trying to chase down a gremlin in my '99 XLT (4.0 SOHC).

About every other time I go to start it, it won't start, because the fuel pump won't turn on (the initial key-on prime where it runs for a second or two).

I basically have to sit there and Key-On/Key-Off for a couple minutes before it'll finally fire, and then I can get it started.

Once it starts, there's no issue - it continues to run until I turn it off.

My initial inclination was to replace the fuel pump, but then I started thinking, that if the fuel pump itself was going bad, it'd cut-out while running.

Where should I focus my attention to resolve this?

 

[donalds]

Start with the fuel filter

 

[German Engineer]

- Check the inertia switch.
- Check the power supply to the pump, and also check for bad ground.

Before you move on to replace the pump (if those or the fuel filter are not the issues) check the fuel pressure first as well.

 

[RickOTR]

Depending on the miles, it could be the fuel injectors leaking down

 

[fast_dave]

About every other time I go to start it, it won't start, because the fuel pump won't turn on (the initial key-on prime where it runs for a second or two).

I basically have to sit there and Key-On/Key-Off for a couple minutes before it'll finally fire, and then I can get it started.

Where should I focus my attention to resolve this?

The easiest thing to check is the 22 year old fuel pump relay, in fuse box in engine compartment.

Pull it and look at the color of the plug-in pins; they're probably brown/blue from all the electricity going through them (all the time) while your engine is running. BUT the pins aren't the problem - it's the contacts INSIDE the relay.

To test the theory - swap it around with another relay - I think the A/C uses the same one.

 

[J_C]

I agree with trying other things first, but disagree with the premise that it would as likely stop working once it is already spinning. Initial failure on a motor like that is often that it ends up at bad spots on the commutator or worn bearings and has more trouble starting to spin than to keep doing it. In other words, I think the fuel pump going bad is most likely.