1991 F250 300ci MT Help!!!! After not starting for over 24Hrs the truck will not start, until I turn key switch to ON and the fuel pump, front or rear tank, runs about 3+ minutes and turns off, then it starts right up as it should. At any time before that point it will not start. Once it starts it will start any time within about 24 hrs. And the fuel pump shuts off within the normal 2 seconds as it should. I am mystified, just bought this truck and previous owner had the same problem, I am afraid it may get worse or lead to something else failing. The tanks switch to each other when they should, truck runs great otherwise.
Any Ideas?????

My other truck is a 1996 F150 4x4 offroad 300ci MT ex USFS
This my first post on any forum of any kind Any help will be greatly appreciated. I love my Truck, my wife I tolerate.

 

sounds like a fuse slowly going bad to me

 

subscribed

 

I would try replacing both the ECM and fuel pump relays. The ECM is what controls the pumps so it's more than likely a problem with a sticking relay or the ECM is not timing out when you first turn on the key, although it's kind of strange that it happens only after the truck has been sitting for a while.
By the way welcome to the forum.

 

I am kinda having the same problem. Not as bad tho. My truck will randomly not want to start. And I mean RANDOMLY. I can be driving it all day. Turning it on and off randomly throughout the day and without warning one time it will just not start. But When it switches from front to back tank it turns over fine.

 

Thanks for the info so far. A couple questions... Where is the fuel pump relay located? And if someone replys 'subscribed' what does that mean?

 

Subscribed just means they're interested in the result, and want to be notified by e-mail whenever someone else posts. If you reply to a post the website automatically subscribes you to the thread, and you get notifications whenever someone replies.

 

My '94 with dual fuel tanks is doing the same thing. It was not as bad before I burnt the ecm (or pcm as I think it's called on mine) and replaced it. It ran fine for awhile, then became very picky about when it was willing to start. After a good rain it might take 1/2 hr to fire up. I replaced the fuel filter and still no dice. When I turn the key forward the pump (both front and back) engage and stay running (no cutoff) until I turn the key off. If I do this repeatedly, eventually the pump sound will stop promptly, and the truck fires right up. I have good pressure at the schrader valve behind engine (not measured, but strong spray) and I have good spark. Very rarely I will get a bump like the engine wants to fire up, but usually NOTHING. Any suggestions would be appreciated.

 

Hi everybody.
to me personally it looks like if there's a leak under the bonnet. If an injector stays open due to dirt between the seat and needle and the non-retour valve in the pump, your gas runs slowly back to the tank.
maybe an idea?

best regards Ton

 

A strong spray isn't an accurate pressure reading.