98 Mountaineer loses power turning Left?

[04mach1]

1998 Mercury Mountaineer, 4x2, 4.0 SOHC, 3.55 regular axle (no limited slip), 125,000 miles

When making left turns from a complete stop, truck loses power and hesitates almost like the transmission is slipping. Only happens on left turns made after a complete stop and only happens randomly. Does not occur every time I make a left turn. Problem started about six months after I replaced a defective fuel pump.

Here is what I have done to correct the problem with no improvement:

1) Ford checked the PCM software to make sure I have the latest flash of the power train control module. Confirmed good.
2) Changed tranny fluid and filter. Old fluid looked perfect and old filter was clean. No metal shavings on magnet.
3) Changed rear differential fluid.
4) Transmission shop checked transmission and did not think problem is transmission related.

Not sure what to do next?

 

[Lube]

Is it related to fuel level in the tank?

 

[04mach1]

Is it related to fuel level in the tank?

Good question. I posted this for a friend I will ask. Thanks.

 

[SoNic67]

Left turns at idle rpm's... to me sounds like an issue with the power steering pump that takes too much power at max left - coupled probably with a marginally bad IAC valve (cannot open completelly to supplement for the power loss).

 

[MrQ]

I have the same problem when the fuel level gets low in my 98. A possible cause is that the sock on the fuel pump came off in the tank. The sock acts like a filter and also helps keep gas in the pump. Without it, when the gas shifts in the tank on a hard turn, the truck loses fuel pressure.

 

[BigPip]

Check your battery cables, make sure nothing is lose.

 

[swetrid]

Fuel pump or the basket that the fuel pumps sits in falls off bottom of tank and disrupts fuel flow. Ford has tsb for this for updated fuel pump. Here is tsb.
Printable View (4 KB)
TSB
00-20-1 HESITATION ON ACCELERATION OR TURNING - LACK OF FUEL PRESSURE - EXPLORER/MOUNTAINEER VEHICLES BUILT THROUGH 8/15/2000 AND EXPEDITION/NAVIGATOR VEHICLES BUILT THROUGH 6/30/2000

Publication Date: SEPTEMBER 21, 2000

FORD: 1997-2000 EXPEDITION
1997-2001 EXPLORER
LINCOLN: 1998-2000 NAVIGATOR
MERCURY: 1997-2001 MOUNTAINEER


ISSUE:
A hesitation on acceleration or while turning may be felt on some vehicles. This may be caused by fuel pump cavitation due to fuel sloshing away from the filter sock in the fuel tank reservoir.

ACTION:
To service, check fuel pressure. Check all fuel pump related electrical circuits. If a fuel pressure concern is verified, refer to the following Service Procedure for details.

SERVICE PROCEDURE

Attempt to verify if fuel pressure drops during the event.
If a fuel pressure drop is verified, check all fuel pump related electrical wiring, connections and related systems.
If all checks OK, replace the fuel pump/sender assembly with a revised fuel pump/sender assembly. Refer to the parts listing for application.
Refer to the appropriate model year Workshop Manual, Section 310-01, for removal and installation instructions.

PART NUMBER PART NAME
F7PZ-9H307-BD Fuel Pump - 1997-1998 Explorer/Mountaineer (All)
XL2Z-9H307-AJ Fuel Pump - 1999-2001 Explorer/Mountaineer (All)
XL1Z-9H307-AB Fuel Pump - 1997-2000 Expedition (4X4)
XL1Z-9H307-BB Fuel Pump - 1997-2000 Expedition (4X2 With Base Suspension)
XL1Z-9H307-CB Fuel Pump - 1997-2000 Expedition (4X2 With Air Suspension)
XL1Z-9H307-DB Fuel Pump - 1998-2000 Navigator (4X4)
XL1Z-9H307-FB Fuel Pump - 1998-2000 Navigator (4X2)


OTHER APPLICABLE ARTICLES:
NONE

WARRANTY STATUS:
Information Only

OASIS CODES:
404000, 609000, 609500, 610000, 610500, 611000, 611500, 614000, 614500


--------------------------------------------------------------------------------

Copyright © 2000 Ford Motor Company

 

[SoNic67]

That TSB applies for "HESITATION ON ACCELERATION OR TURNING".
OP complain was on "TURNING LEFT FROM STOP".
Those are not the same issues in my view.

 

[04mach1]

The problem started six months after the fuel pump was replaced and fuel level has no effect. Do you think that the sock would come off after six months?

 

[keepinitoldskool]

it's called Nascarophobia, it is a recessive gene found in Fords

That TSB applies for "HESITATION ON ACCELERATION OR TURNING".
OP complain was on "TURNING LEFT FROM STOP".
Those are not the same issues in my view.

Turning left from stop involves "acceleration or turning" so I would definately look into that tsb

 

[gavin]

so just turning the steering wheel left, without actually moving, has no effect, correct?

That TSB applies for "HESITATION ON ACCELERATION OR TURNING".
OP complain was on "TURNING LEFT FROM STOP".
Those are not the same issues in my view.

turning left from stop would include both acceleration and turning, no?

 

[04mach1]

so just turning the steering wheel left, without actually moving, has no effect, correct?


Correct.

 

[siddy_52]

Did the TSB solution fix the issue. MY 1998 Explorer XLT 4wd is having the same symptoms.

 

[siddy_52]

Did the TSB solution fix the issue. MY 1998 Explorer XLT 4wd is having the same symptoms.