1998 Ford Ranger Engine stalls/hestitates going uphill

SKYGUY

MEMBER
1998 FORD RANGER
6 CYL
4WD
AUTOMATIC
170,000 MILES

Hello,
I have a 98 Ford Ranger 4x4 with the 4 litre engine and auto transmission. The engine stalls or hestitates when going up fairly steep hills. This always happens on the steeply inclined parts of the rough, bumpy, backcountry dirt roads over which I travel most of the time. On paved highways and the grades encountered on highways the engine performs well, even when accelerating up a paved incline at highway speeds. But at slower speeds on inclined backcountry roads there is a problem, and regardless of whether the tank is full, half full or nearly empty. However, the engine only stalls/hesitates when going forward. It works fine in reverse, backing up any hill no matter how slowly, steeply inclined or bumpy. The fuel tank has been removed, inspected and was found to be very clean, the main fuel filter replaced, and the pump appears to be working.

I brought the truck with me from Canada to Nicaragua where I now live. Most mechanics in Nicaragua know very little about fuel injected gasoline engines since most vehicles sold in this country are diesel. A mechanic from a garage I use went out with me for a road test with a fuel pressure guage and the fuel pressure checked out OK for city and highway driving. Unfortunatley the garage is over an hours travel from the type of road conditions on which I am having problems and they didn't want to send a mechanic out for several hours even on my nickel. (And, yes, this is the only garage I come close to trusting) So, any thoughts or help with what the problem could be would be greatly appreciated. Many thanks.

Alan (aka Skyguy)
webaccounts@live. Com

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,740 POSTS

It does sounds like a fuel problem; however, has the check engine light ever come on? Also, when you had the tank out, was the wiring to the sending unit (fuel pump) inspected for corrosion and a good tight fit? Finally, when it dies on you, does it start right back up?

Let me know.

Joe

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Saturday, December 26th, 2009 AT 11:39 PM

SKYGUY

MEMBER
4 POSTS

Thanks for your reply.

The check engine light flashes on (then off) very quickly when the engine stalls/hesitates. After hesitating it does start right back up. The stall/hesitation is more like a "hiccup" rather than completely dieing.

Regarding the wiring, I don't recall anything looking particularly out of sorts (corroded, loose) but then I probably didn't pay very close attention not knowing exactly what I was looking at.

Just to throw out a few thoughts. (Apologies if I'm getting the terms wrong, and please correct me if I'm off-base)

I seem to recall seeing a float mechanism connected to a sensor/switch as part of the in-tank pump assembly. Since the problem only appears on rough roads uphill, could this "sensor" be malfunctioning and behaving erratically due to jarring or gasoline sloshing around more under these conditions?

Also, there is an emergency fuel pump cut-off switch. Could this be malfunctioning due to rough road vibration when the engine is under heavier load going uphill?

And, is fuel pump failure 100%. Despite the test run with a fuel pressure gauge showing good pressure on the highway and around town (and even up a fairly steep paved incline), could a pump be "dieing" and affected by rough road vibration/jarring and higher engine loading at slower speeds going up steeper inclines?

Thank again for helping out.

Alan

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Monday, December 28th, 2009 AT 10:40 AM

SKYGUY

MEMBER
4 POSTS

The consensus from various forums, plus the local Ford dealer in the hometown of some friends in Canada who rallied to help, was that the problem could be with any or all of the coil pack, high tension wiring harness or the plugs. Turns out it was the plugs. I replaced them and the engine runs fine.

As a side note, it appears the problem was specifically with the 3 plugs on the right side of the engine (left side if you are standing in front of the vehicle looking at the engine). The long white ceramic insulator that the cables snap onto all had dozens of small, vertical cracks in the top half. The 3 plugs on the left side of the engine appeared fine. Does anybody know what would cause such cracking/crazing and why it would only happen to the plugs on one side of the engine?