Fuel pump?

[GeorgiaJeeper93]

So the truck that I've had for exactly one week today broke down. Driving up some mountain roads, I came over the top, shifted into 3rd, and it died. I started it back up and it was idling rough, then dying. Wouldn't make it more than 100 yards before dying again while driving. Had to get it towed home. Where is the best place to start? Fuel pump? Filter? I'm clueless.

[onlyinajeep726]

Year? Motor?

[gogmorgo]

Check your fuel pressure before you start pulling things apart. You can also try bypassing the fuel pump ballast resistor.

 

When my fuel pump went this summer it was more of a slow failure, the pump getting weaker and weaker, not all of a sudden. But there are many potential failure modes.

[GeorgiaJeeper93]

It's an 88 4.0. 180xxx miles. Not really sure where to begin. I've never had a problem like this before.

[Hippie66]

Mine started cutting out, but kept running. Filter was full of rusty water, some got through and plugged the injectors. I ended up replacing my tank, pump, lines, filter, and upgraded the injectors.

 

Pull the filter and see what comes out of it.

[Knucklehead97]

http://comancheclub.com/topic/45860-bosch-aftermarket-fuel-pump-installation/?view=getnewpost

 

For if you change the fuel pump :D

[johnj92131]

Check your fuel pressure before you start pulling things apart. You can also try bypassing the fuel pump ballast resistor.

 

When my fuel pump went this summer it was more of a slow failure, the pump getting weaker and weaker, not all of a sudden. But there are many potential failure modes.

 

X2 on this.  Last Friday, I just had the fuel pump replaced with the Bosch 69302 replacement pump (Got an Amazon Warehouse deal for $31.00 - saved $50)  Shop charged me $130 to replace the pump. If you do have to replace the pump, don't forget a new gasket, lock ring, and pump intake sleeve.

 

First check the fuel pressure in the fuel rail.  Should be about 35-38 and it should hold that pressure when you turn the engine off.  My old pump did not hold the fuel pressure and fuel just leaked back into the tank.  So no fuel at the injectors = engine not running.  This was a slow, intermittent failure. Just as gogmorgo described.

 

The DIY how to Knucklehead referenced is EXCELLENT!

[metrictonner]

Remove your fuel pressure regulator from the front end of the fuel rail.  Stick in a drain hose into a clean bottle.  Turn on the key (no need to crank the engine) and see what comes out.  No fuel.  Dirty fuel.  Low pressure.  High pressure.  Its the regulator that maintains the 39 psi fuel pressure (minus manifold vacuum), not the fuel pump.  Generally a good fuel pump will blast fuel through an unregulated system with enough pressure to clear most obstructions, like a thumb over the end of the open fuel rail.  Be prepared to block spraying fuel.

 

If the fuel pump isn't getting power the engine will fire up and die, not fire up and run 100 yards.  Generally fuel filters don't clog up all of a sudden.

 

My guess is check for crud in the fuel line, input to fuel rail and drain back to fuel tank or a bad pressure regulator.