Explorer stalls when hot

[canthony15]

No codes. Before changing the fuel filter and the pump yesterday, the idle was fair. It idled steady but with a couple of "bumps" every second or two. Like small misfires but not enough to throw a code. It seems to be better with the new filter and pump but I don't have enough drive time to say for sure. It had it's better days and worse days as far as idle so maybe I just had a better day yesterday. In any case the idle was not that bad. It wasn't threatening to stall or anything.

However, when it gets really hot out and I drive it for a good long distance, as I said already, the idle will go into the mode where it cycles up and down by a few hundred RPM and the car will try to stall when I take off from a standstill.

The other symptom was what I would call "hard hesitation" when I take off from a standstill. This only happens when it is hot out and it doesn't happen often. When I push the pedal to start accelerating I go a few feet and then it acts like the engine dies for a second. Then it catches and I'm off and running. This is the symptom I am hoping to fix with the fuel pump and filter.

Like I said, earlier, new MAF, new IAC, new PCV. Checked the EGR valve and it is OK. Have not checked DPFE. Did the carb cleaner test for vacuum leaks and found nothing. Now a new fuel pump and filter. Fuel pressure (before changing the pump) was good but I measured it cold.

With the temperature down a little, I drove the car all last week, 50 miles a day, without any events. I kept the AC off though because it seems to increase the odds of failing when I run the AC but I'm not sure about that.

I'm not holding my breath that the pump/filter is going to help with the cycling up and down thing. I am hopeful for fixing the hard hesitation though. That is actually more of a danger because it happens unpredictably when I am taking off from a standstill. There are too many times when I am turning in front of oncoming traffic when the thing hesitates like it's going to die in the turn. Scary.

 

[Midwest Dually]

Very understandable!

A long while back I was having a similiar issue with a Ranger I owned. Many of the same symptoms you are listing is what I was going through, up to the point that when it got really hot out, it vapor locked.

I replaced the MAF several times (expensive part), fuel pump, fuel filter, fuel pressure regulator, injectors, inertia switch, harness... I even upgraded the Rangers Fuel system to the Explorer's (Ranger fuel lines were looped at the filter, which could cause pinching of the line under heat).

Needless to say, I put it out to pasture. Later on I was reading somewhere about the fact the ECU is what determines grounding for the fuel delivery system on a variable fuel system, and under increased outside ambient air temperatures, and AC load, can fail to ground the pump, causing it to shut off, when the ECU is bad.

I am not sure if this is your problem, but if it continues, and you don't get it solved, this may something to check into as a last resort!

 

[Torqueranger]

I would check out the crank and cam position sensor...

 

[canthony15]

Well, it might be a little premature but I think it is fixed. The fuel pump and filter seem to have done the trick. I haven't had a single hiccup in the past 5 days and two of those days were pretty hot. Today, while it was in the low to mid 90's, I drove down to a flea market with the AC on. It was about 35 miles round trip. The temp gauge rose about a needle width above normal, even when sitting in traffic at stoplights. But that was it. No stalls or funny idle behavior. AC was nice. If the problem comes back, I will post. Otherwise, I think that's it! I still need to run it up into the mountains on a hot day but I am feeling lucky .

 

[joe doe]

However, when it gets really hot out and I drive it for a good long distance, as I said already, the idle will go into the mode where it cycles up and down by a few hundred RPM and the car will try to stall when I take off from a standstill.

The other symptom was what I would call "hard hesitation" when I take off from a standstill. This only happens when it is hot out and it doesn't happen often. When I push the pedal to start accelerating I go a few feet and then it acts like the engine dies for a second. Then it catches and I'm off and running.


With the temperature down a little, I drove the car all last week, 50 miles a day, without any events. I kept the AC off though because it seems to increase the odds of failing when I run the AC but I'm not sure about that.

mine still does this ..exactly as you describe. funny you mention the a/c as mine seems to cut out sooner when i run the a/c .or are we just imagining this?
i will continue to check on your progress. my ex has 157,000 on it with the original pump so i guess i cant complain .but i sure have put more money in it then its currently worth .
my mechanic will not just throw a pump in ,he wants me to buy the whole assembly (pump/float together) so with the price of that plus install this could run me 3 bills.
thanks for the update.keep them coming .

 

[Turdle]

When the ecu detects an over temp situation --it will raise the idle and deliver more fuel in attempt to cool. Climbing those mountains is no babywalk.


That being said, have you replaced the ECT sensor?

There are 2 temp sensors on the engine. One is merely a gauge sender, the other is an actual sensor which provides temperature data to the ecu.

Oh, and the IAC could have a dirty plunger and be sticking open --heat might even make this worse. Just some suggestions for you to ponder.