[MagmaJct]

Originally Posted by Hennyhog

First off...thanks for all the feedback! Ok...so I put on a new set of plug wires Thursday evening. Truck ran great to and from work Friday and even work and errands Saturday morning. Then as my wife and I were out for a spin in the afternoon it happened again. Yeah....it's a bummer but have to keep at it so what am I going to try?

1. Some have mentioned that fuel lines near exhaust and even leaning against radiator hose may be vaporizing due to heat. The truck has had this happen to it 3 miles from home after having only been running for 5-8 minutes or 40 minutes after running it. So I kinda want to rule that out.

2. I'm pretty sure my fuel cap has a pressure relief doohicky in the center (little blue plastic piece) and when I fill it up I've never had that "whoosh" of air escaping while undoing the cap.

3. Still haven't read too many posts about intermittent mechanical fuel pump issues that act the way my truck is suffering from.

So with the crappy weather up here in MA I'm going to wait till later in the week to pull line off fuel tank sending unit, inlet side of pump, blow it out, and put a new pump in. They are cheap and it'll be another thing to rule out.

I still can't wrap my head around how it can be the pump (my brain tells me it works like a light switch. it's either off/on or pumps fuel or doesn't. I surely will keep you posted!

Thanks,
Henny

I told you my story. Perhaps my story doesn't sound like yours to you, but your story sounds like mine to me.

I too wouldn't have thought a mechanical fuel pump would be intermittent until it died completely forcing me to see that it was indeed bad. Once replaced, years later the truck has never died from lack of fuel.

That "whoosh" from the gas cap does have me a bit concerned. It is my understanding the cap is supposed to let air in to prevent a vacuum, but block vapors from escaping, instead allowing them to vent into the charcoal canister. If the tank developed a vacuum this can cause fuel vaporization ahead of the pump.

Regards,
Mike