<HR style="BACKGROUND-COLOR: #d1d1e1; COLOR: #d1d1e1" SIZE=1 itxtvisited="1"> <!-- / icon and title --><!-- message -->
<!-- BEGIN TEMPLATE: ad_showthread_firstpost_start --><!-- END TEMPLATE: ad_showthread_firstpost_start --><!-- In 1st Post Ad --><TABLE border=0 width="100%" itxtvisited="1"><TBODY itxtvisited="1"><TR itxtvisited="1"><TD vAlign=top width="100%" itxtvisited="1">Hello all
a couple quick questions ( 1998 f 250 4 wheel drive 5.0
what controls the <NOBR style="COLOR: darkgreen; FONT-SIZE: 100%; FONT-WEIGHT: normal" id=itxt_nobr_2_0>fuel</NOBR> pump, Im not getting any pressure at the rail. The filter is clean and the fuel pump turns on for a second and then turns right off .
Is there a fuel pump in the tanks (Its a duel tank <NOBR style="COLOR: darkgreen; FONT-SIZE: 100%; FONT-WEIGHT: normal" id=itxt_nobr_3_0>truck</NOBR>,but i have the sanme problem on both tanks), so I dont think thats my problem.
I have change the fuel pump relay,fuel filter ,control mod that mounts on the side of the distributor,
Any ideas ???
thanks</TD></TR></TBODY></TABLE>

 

Is this a `88 truck? If so you have three fuel pumps, one in each tank and a high press. one on the frame rail. Sounds like the high press one may have failed.
Hopefully some other opinions soon.

 

I take it this is your 1989 Truck.
It is controlled by the EEC Computer by way of the fuel pump relay. It only runs for one second when the key is first turned on and then runs on a one second timeout each time the EEC Computer see a PIP pulse from the distributor.

Yes there is a boost pump inside each tank to prime the fuel system and help the high pressure pump when the tank is low or you are on a hill. But is not needed after the system is primed if the tanks are more than ¼ full and you are not going up a hill or making rabbit jump starts with the truck.
If you turn the key on and off about four times and you still do not have fuel pressure the the Ignition System PIP is not the problem.

As Lazy K said above check to see if the High Pressure pump on the frame is running for one second when you turn on the key. If it does then lessen at the selected tank to see if the boost pump also runs for one second when the key is turned on. If it does then remove the pressure line from the selected tank going into the fuel selector valve, aim it into a bucket and turn the key on and off and see if you get about 7 PSI fuel pressure and a flow from the fuel line.





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