My truck is an instant-start old girl and has never left me on the side of the road. Except, when I let her sit for a month or two as I sometimes have to do. She will then still start instantly but will only run about 45 seconds before dying - I can then crank her a few times and she will start and run another 30 seconds or so before dying again - then after a little more cranking she will start and run fine. It never does this if I'm using the truck on a regular basis - I can even let her sit a week or so with no problem. Could this be a weak fuel shutoff that's sticking when I let it set a month or so? I did change the fuel filter today and it was pretty gunked up so was thinking this might have been part of the problem as well. What do you reckon?

 

I would say it sounds like you are getting air in the lines possible.

 

While I don't know the answer, 45 seconds until it dies? that's a long time, plenty of time for a "good" lift pump to feed the entire system air or not, but air is about the only thing that will stop a 12v so its getting in somewhere. The shutoff switch would stop it cold just after you left off the key. I will keep this thread in my fav list to see what everyone else thinks.

 

it is air and most likely entering beside the filter

 

As the others have said, air leak.

Try this, after setting for a long period, use the primer to refill the system, go until you hear a hissing sound like forcing air thru your front teeth.

Then see if she fires right up and stays running.

 

The problem I see with this is if it fires up right away, it has fuel at the pump already, so it may just squeal like it should right away. I'm betting the leak is before the lift pump.

The other thing to check is to see how much fuel is in the fuel filter once it dies. Sounds like its a big bubble that its getting hit with. Give you an idea how much air there actually is.

 

I think you've got it pinpointed - I will do the diagnostics and let you know - it may be a while til it happens again.