Fuel flow

gasoline

#1

My son drives a 1997 Jeep Grand Cherokee Orvis 4.2L with 116,00 miles. Every so often when starting from a dead stop, the motor hesitates; it chokes like it’s not getting enough gas. It does this for about a second or two and then runs fine. We’ve had the injectors professionally cleaned, had the gas tank removed and cleaned out, and also replaced the fuel filter. It still does this every once in a while - and it’s more frequent when the gas level is at or below 1/4 tank. Any suggestions?


#2

Correction: The 97 Grand Cherokee has the 5.2L V-8.


#3

[b]Was the fuel pressure ever tested? One thing that can cause this problem is a weak fuel pump.

The level of gas in the tank can assist a weak fuel pump in maintaining the proper fuel pressure. This is done from what is called head pressure. Head pressure is developed anytime there’s a column of liquid and gravity applies a force to it. As the liquid level drops, the head pressure decreases. If the fuel pump is marginal, and the level of gas drops in the tank, the head pressure can drop to a point where it no longer assists the weak fuel pump. And that’s when drivability issues can arise.

Tester[/b]


#4

Yes, the fuel pressure was checked. In fact, it wasn’t the fuel filter that was changed as I indicated, it was the fuel pump.


#5

Also, the computer never shows a code, so this has been a guessing game, but after doing more research, the mechanic now believes the problem may be with the fan clutch. Before I spend another $275, I’d like a second opinion about that.