Bronco Fuel Delivery Issue

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Travisfab

Moderator
Staff member
Aug 21, 2003
19,964
188
63
San Diego
#1
I'll preface, by saying my truck has sat for 4 years without being started. Issue is that I am not getting pressure to the rail.

Obviously (likely not important) issues - 5 warning beeps when the key goes in (air bag related I believe), and I am having to manually jump the solenoid (should not be related).

I am hearing the pump prime when the key is turned. With both lines disconnected from the pump, I am getting fuel spraying out of the smaller, grey line.

The blue line goes directly from the tank, to the fuel filter. The arrow on the fuel filter is pointing towards the front of the truck. I cannot understand why the fuel pump is not pushing fuel through this line. Am I correct in thinking that fuel should exit the tank via the blue line, go through the filter, and then into the engine? Excess gas would then be returned via the grey line?

If this is the case, why would I be getting fuel shooting out of the smaller grey line?

 

Tchajagos

Senior Member
Feb 12, 2010
1,597
5
38
Riverside
#2
I believe the fuel line fittings are different sizes so you wouldn’t be able to switch them on accident. But I believe you had them extended right? Maybe they mixed up the ends. You can pull out the fuel pump to see which one actually is fed by the pump and which is the return. The 3rd one in there is just a reinforcement to hold the pump assembly together.
 

84prerunner

2:AM Fabrication
Feb 7, 2008
21,483
54
48
Covina CA
#4
so when the pump primes with both lines off the pump, fuel shoots out of hard line on the right? If thats the case, that lines needs to be going to the filter/rail, not directly to the regulator.
 

ItzEnsign

Senior Member
Jul 24, 2012
703
6
18
Canyone Lake
#5
Two things I can think of. Did you attach the fuel pump wrong? I know on mine it’s just a rubber hose and c clap attached to pump in tank. Did you attach it to the wrong one? I only remember there being one easy to get too. Second which wouldn’t make too much sense, fuel filter clogged? Fuel pressure in tank builds up and pushes out the return?


Sent from my iPhone using Tapatalk
 

04yfzkid

I are smarts
Mar 21, 2007
33,365
230
63
Flagstaff, AZ
#6
You have a supply, return, and a vent it appears in the picture. If the supply isn't getting pressure at the rail / regulator, you have a plumbing (most likely) or a wiring issue (doesn't sound like it). Yes you are correct in the assumption. It should go from the tank, through the lines, fuel filter, and then rails, and return excess pressure / fuel through the return. Some vehicles the fuel pressure regulator is before the fuel rail. In my opinion the best option is to run it to the fuel rail, over to the next, exit after the last injector then into the fuel pressure regulator(FPR). This makes sure all the injectors see the same pressure vs a drop over the injectors as they are fed a certain psi and may drop as each injector opens. If you want, give me a call today or tomorrow and I can try and help. I did quite a bit of fuel related stuff in my street car days.
 

Travisfab

Moderator
Staff member
Aug 21, 2003
19,964
188
63
San Diego
#7
The issue was within the fuel delivery module. It's a big plastic piece that the actual pump plugs in to. Fuel is pushed out of the pump and diverted through a small 1/16" orifice that was blocked. I was able to clear out the clog and immediately get pressure to the rail with just a few key turns. So the Bronco now runs!
 
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