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Fuel Pump !!! No Pressure at Fuel Rail!!!

6K views 2 replies 2 participants last post by  lostboy 
#1 ·
I need Help !

'92 4.0 Wrangler
Changed Fuel filter and fuel pump. Tried to start it and bleed off air at the injector fuel line. I had pressure than the fuel rail had no pressure...
Checked fuel filter direction flow arrow face to front looks ok. Dropped the tank checked hook up, and replace fuel pump with another new one.
Turn key on fuel pump will pump than goes off, still know pressure at the injector fuel rail.....
any areas I'm missing????
I don't think fuel line is blocked. fuel pump does not fill fuel line with fuel ???
 
#2 ·
Fuel pump will shut off when it senses no demand. Tip I got was to turn key,wait for pump to shut off, bleed rail....repeat several times until fuel flows steadily...it may take several tries to bleed the fuel rail
 
#3 ·
Before I get beat up on here,let me clarify.
The fuel pump actually pulses.When fuel is not flowing to the injectors,there is back pressure in the line and the fuel pump will shut down. Same thing with air in the line...too much back pressure and the fuel pump shuts down until the pressure is released.
It's the job of the fuel pressure regulator and the fuel return line to keep the rail at a constant pressure under different demands.
 
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