need help i have a 1994 f250 that drove yesterday today the truck will not start it has spark and u can here the fuel pump but will not start unless i spray fuel in plenum then i can drive the truck runs ok but if i shut it it will not start than thanks don

 

if it runs on gas.check your fuel filters first. then check to see if you are getting enough fuel pressure at the injecters. on your fuel rail there is a spot to put a pressure gauge , just because the fuel pump making noise don't mean it giving out enough fuel psi.

if it diesel. the check your glow plugs first,then check the glow plug timer to make sure it working.. then check filter and fuel psi.

 

hey thanks it is a 5.8 if i spray fuel in the plunum i can start n drive the fine i am thinking if the fuel filter was bad the truck would not run it all

 

Do you hear the fuel pump run when you first turn the key on?

 

not alwise. some filters slowly plug up over time. like some one slowly turnoff the water. when it get to the point and it not letting enough fuel get by, that when you start to have problems. like week fuel pressure. most EFI'S run high at 30psi to 35 psi but if your only get say 20 psi .then you don't have enough fuel for the peak demand. like when starting or when the foot on the gas.

 

You might try turning the key to "run" position for a few sceonds, then "off" again, then "run" again for several seconds a few times before trying to crank it.

I doubt it's a fuel filter problem, they usually affect your high speed performance before normal running or starting.

 

yes i do here the fuel pump come on an it will start and drive if i spray fuel in plenum thanks don 4 your help

 

fuel filters effects any time you want fuel to go throught the it!!.

some times it effects it all at once and no fuel get through it.

some times it effect it at high demand for fuel like at high rpms or when you have you foot in to past some.

some times it effect it at low speed when your pulling a loooooong hill .

its called a filter and it effect your fuel PSI by not having enough out-put flow to keep up with what the injectors are need at that time. if you have low fuel pressure and cause it not to run or start!
at starting your fuel mixure is very rich (most are 18 through 21 to 1)compared to the 12or13 to 1 mixture while it running.
easy check for fuel filter or fuel pump problems is by just putting on a fuel psi gauge at on the fuel rail port and see what psi you got at any rpm.

turning the key on and off and on again ,then it starts . shows you have weak fuel fuel flow or pressure..

 

We are dealing with both pressure and volume,....before the filter and after.
Assuming a constant pressure before the filter, enough to supply the necessary volume and pressure after the filter for the engine to operate for normal driving once started, there will be plenty of volume getting past the filter to supply enough pressure to start the vehicle.
Although the mixture is richer, the volume of gas used at closed throttle startup is lower than that of driving at normal highway conditions.

Pressure no,..........flow yes.
That's why I asked the question.

 

I would clean and tighten any/all ground wires on top of the engine. If that fails I would think of replacing the temperature sensor.

 

Bottom line is check fuel pressure when the key is turned on, if it doesnt build and hold at least 35psi after 2 cycles you have fuel pump problems.

 

don here i 1st changer the fuel filters to see if it would start.nope if i cycled the 8/9 times then it would start so i borrowed fuel pussure gage it had 2 psi at the shrader valve. so i put a new pump still the same had 2 put gas in plunum to start is so my next step would the hardess to get 2 fuel regulator fun and games still no luck had 2 spray in plunum2 start B/T/W this is my 1st 4 letter word truck allways had bowties b4

 

don here i 1st changer the fuel filters to see if it would start.nope if i cycled the 8/9 times then it would start so i borrowed fuel pussure gage it had 2 psi at the shrader valve. so i put a new pump still the same had 2 put gas in plunum to start is so my next step would the hardess to get 2 fuel regulator fun and games still no luck had 2 spray in plunum2 start B/T/W this is my 1st 4 letter word truck allways had bowties b4