98 Mountaineer loses power turning left

[Rick Hite]

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?

 

[EddieS'04]

Problem started about six months after I replaced a defective fuel pump.

Sock fell off the fuel pump and loosing suction. Or something to do with the pump.



I had the same problem with a t-bird. Sock strainer came off the pump. When the tank was below half. It would loose suction.

I dont know about the mounty, but. My pump sock sat in the bottom a tray. That channeled the fuel to the pump. when making turns. So it wouldnt loose suction.

 

[brian brown 3]

Dude, easy fix...





Only make RIGHT TURNS...



Haha.. I know that was lame...



Ok.. here's a place to look....



Does Ford products have a kick out switch for when the steering wheel is sharply turned. It switchs off certain power robbing items so the engine will not stall and keep the power steering pump running. Some car lines have this.. and Maybe.... this is it??



Good luck! let us know if you ever figure it out



Brian B

 

[Jeremiah Morgan]

first thing I thought of was power steering cut off switch. I have seen it do some funky stuff before..

 

[A Morrow]

Had a similar problem in my old ford focus, it ended up being dirt in the gas tank, had to drop the tank to get it out.

 

[Richard L]

I don't see any relationship between left turns and a fuel pump problem? If the sock fell off the fuel pump pickup I would suspect that the loss of power would occur occasionally under other circumstances and not just when turning left from a stop. I suspect that it is either a problem with the power steering, or an intermittent electrical short.



The Power Steering rack may have some kind of debris that is clogging up occassionally and that is causing an excessive load on the power steering pump and dragging down the engine rpms? I would test this by simply turning the wheel left and right, from lock to lock without actually moving the vehicle to see if you can duplicate the problem. You may need to do this a number of times since the problem is intermittent. That will eliminate transmission problems, or gas sloshing in the tank and interrupting the flow of gas to the fuel pump as the cause.



The other possibility is that turning the wheel may be pulling on a some wire. Perhaps some sort of wheel sensor, or speed sensor that is causing the ECU to short out momentarily and then reboot and causing a loss of power? Perhaps there is some other wire, harness or connector that has come loose and/or is being moved by some steering part?



I have even heard of people who had a problem like this that was caused by their battery not being properly secured so that it would move and short out a battery terminal when the vehicle turned. This is probably not your problem, but it is always good to just check for those strange or bizzare things...since they do happen.



...Rich

 

[Kevin Lang]

My old buick lesabre (1992 model) had a similar issue, only it was with right turns. Turned out to be the fuel sock had died leaving white gunk in the tank that would temporarily clog the fuel delivery system, something that was fairly common to that model. I guess this backs up what others have said, though my issues only came up under 1/2 tank of gas.