No Fuel at Rail on 87 5.0 bronco

[Wolfpacsrevenge]

okay heres the deal I have an 87 bronco with a 5.0 and i can not get it to run properly. the truck sat for a few months and then i needed it when i went to start it the truck fired right up and idled for about 30 mins. Then died out tried to start it again but would start and then die out finally figured it was out of gas put about 2 1/2 gals in it and still nothing messed around with it for awhile making sure fuel was comeing from the low pressure pump in the tank to the high pressure pump on the rail and to the filter and just after the filter and it was then checked the sracheder valve on the rail....no fuel....continued to try and start it but nothing happened...went inside for about 2 hrs came back out and it started on the first try and i let it run for about 20 mins seemed fine.....noticed a leak at the sracheder valve and figured id fix it the next day.......went out to start it again and the same problem no fuel at the valve after about 10 mins it started to leak at the valve and it would start but acted like there was not enough pressure.....put a pressure gauge on it and it didnt even register.... now heres the million dollar question... im pretty sure its a pump issue but without throwing parts at her how do i figure out whats wrong..... please help ( [-o<

 

[BroncoJoe19]

messed around with it for awhile making sure fuel was comeing from the low pressure pump in the tank to the high pressure pump on the rail and to the filter and just after the filter and it was then checked the sracheder valve on the rail....no fuel....

I'm not clear... at which point is it that you have no fuel?

OK.. obviously not at the rail, but after the filter?

 

[Wolfpacsrevenge]

i have fuel after the filter and there is occasionally fuel in the rail but not enough to keep it running i have little to no pressure in the rail not even enough pressure to get anything more then a dribble out of the valve and no where near enough to register on the pressure gauge

 

[BroncoJoe19]

I think the only thing between the filter and the fuel rail is the fuel pressure regulator.

 

[Krafty]

sorry to say it stevet83 but your are mistaken, it is mostly right except

the fuel filter is after the HP fuel pump

so it goes

HP pump

External inline filter

then Fuel rail

then FPR

then so on

 

[BroncoJoe19]

Since you stated that you have fuel AFTER the filter; regardless if the fpr is at the beginning (as I thought) or at the end of the rail, that is my guess for a low/no pressure at the schraeder valve, unless the valve itself is clogged, or the lines are crushed/clogged between the filter, and the shraeder valve.

Another thought, did you use a fuel pressure guage to test for pressure? Are you sure that the spindle in the valve was depressed? Do you have a valve insert removal tool?

My real guess is that you may have some fuel flow, but no pressure after the filter.

 

[Krafty]

ie change the filter, or if the pressure is not building up to the filter then the pump. easy way to test it..

first with everything together turn the key to on (not start) with someone opening the Schroeder valve ( ONLY open the valve briefly when the pump is running) to prime the pump and get the air out of the line, turn the key off then back on to re prime the pump. if fuel sprays out then all is well from pump to rail. if it does not spray then continue test

one remove the clip and fitting from the hp pump that goes to the filter, then remove the clip and fitting that goes from the filter to the fuel rail. connect the line to the fuel rail to the hp pump, now turn the key to on and off then on as before, and check pressure to the fuel rail with the Schroeder valve open when the pump is running.

if fuel does spray this time and didn't before then the filter is clogged and needs replacing.

if fuel doesn't spray then the pump needs to be replaced.

also to check fuel reaching the hp pump pull the clip off the back of the pump from the reservoir and with the key on have someone observe a healthy flow of fuel.

if the pump does not run for 2 sec when the key is turned to on then wiring , pump or fuel pump relay is malfunctioning

 

[Wolfpacsrevenge]

if fuel doesn't spray then the pump needs to be replaced.
also to check fuel reaching the hp pump pull the clip off the back of the pump from the reservoir and with the key on have someone observe a healthy flow of fuel.

i have fuel at each pump and after the filter but what should i consider a healthy flow???? some one told me that if i was to remove the top line off the filter (the line that goes from the filter to the FPR) that it should come out fairly powerfull..........and the other question is ....Is it possible for the HP pump to PULL enough gas through the low pressure pump...... or is there enough pressure for the low pressure pump to PUSH fuel through the high pressure pump?????

 

[Krafty]

you could have jumped straight to the answer, breaking down every part to put in your info was not necessary.

also the removing the air was simply for the purposes of doing the test so that if there was air that comes out then he would not get confused by the lack of fuel flow.

so long post short.

swap the lines so that the line coming from the filter goes directly to the fuel rail, and the line off the FPR is the return line that goes back to the reservoir.

then try again.

 

[Krafty]

whatever dude just chill, we're not here to argue ,( like alot of people do on my other thread) its about helping people.

 

[Krafty]

Steve83. .. grow up man.

Wolfpacsrevenge keep us updated on your bronco and let us know if you get that fuel problem figured out.

cheers.

Krafty

 

[Wolfpacsrevenge]

hey guys first i want to say thank you for all the help you have giving me. but i think i might have misled you guys on some of the info that i have given you and for that i am sorry so let me see if i can clear up some of the stuff.....the fuel system is the same way as it came from the factory it has not been removed or altered in anyway ( other then fuel filter changes and i have replaced the HP pump about 3-4 yrs ago) the truck has been parked for about 6 mo and when i put her away she ran fine but now she will not run i will tell you all that i know about my fuel system stating first that to my knowledge that the LP pump is original and that the Fuel level gauge stopped working ( probably from varnish build up)....now i have checked the following there is fuel GOING to the HP pump there is fuel AFTER the HP pump and there is fuel AFTER the filter... however there is little to no fuel at the schrader valve on the rail and there is no pressure reading from my fuel pressure gauge attached to the valve.... now in my opinion i think its the HP pump but i am short on cash and would like a majority vote before i spend the money on my guess ......i think that should clarify some misconceptions there might have been and if there are any questions please ask as this is my first question i have ever posted on a forum and am sorry if i have misled anyone on my problem

Thanks

 

[BroncoJoe19]

According to Haynes,

The low pressure pump should deliver 6 ounces or more in five seconds.

They recommend raising the front end higher than the rear to reduce the likelihood of gas siphoning out of the tank once the hoses are disconnected.

To activate the pump one can jumper the fuel pump in the Self test connector to ground.

There is a picture of the connector and its location in this link

How to scan FORD on board Diagnostic Trouble Codes (DTCs) in your driveway

Howto Pull Codes 1983-1995 Broncos, Mustang, F series Trucks, Econolines, 302, 351 and more

 

[Wolfpacsrevenge]

Thanks to all who took time to help me with my problem I have replace the HP pump and Filter and she purrs like a kitten on steroids again /