2001 harder to start when cooler/cold

[Veg]

2001 expl EB
V6 4.? Something
4x4.
82,000 original miles
Tuned up In August 2019
(believed to have been original plugs and wires)
Was having this same problem during the cooler months BEFORE the tune up,

Hard to start when cold, no so bad during warmer weather. 50-55 degrees plus slight hesitation below 50 degrees...
1 it’s as if there is a delay with getting fuel to the places it needs to be to make it run.
2 then once it starts, it’s a very delicate dance with the pedal, press to hard. It will die
3 don’t press it at all and it will die.
4 to me it seems like either something maybe building pressure or something is warming up ( some type of cold weather choke)
BUT once it gets to Pressurized and /or warmed up it starts like a champ for the rest of the day.

Would like to have an idea where to start before I take it to the shop... or if there is a history of starting in cooler weather

 

[donalds]

I would start with the coolant temp sensor
You can test it
And it's cheap

 

[koda2000]

If you haven't already done it, replace your fuel pump. Intermittent/hard starting when the weather turns cold is a classic sign of a worn out fuel pump.

 

[XLTrunner]

Try cycling the key 2-3 times (OFF-ON) to build pressure before turning it to START and see if it resolves the cold start problem. That's how I'm dealing with it for the time being. Makes all the difference in the world in how it starts/runs at cold start-up. I'm obviously experiencing a fuel pressure leak-down when truck sits overnight or longer. I suppose that's pump related and a new pump will be installed at some point...but otherwise, pump has continued to perform just fine over the past couple years I've been doing this.

 

[Veg]

Fuel pump it was, had it and the filter replaced, starts like a car should. thanks for the replies back
Mech advised it would only build 1/2 the pressure needed to run... eventually it would get enough pressure to operate, can really tell a difference in the every day driving as well, much more power!!

 

[pcrussell50]

mine is completely temp related. the longer it sits during the winter (Denver) the harder it is to start. priming (cycling the key on/off) helps if it's not too cold. but if it's been at or near freezing all day and still freezing the next morning, even priming the doesn't work. complete no-start. in summer even in scorching Nevada summer heat, it starts every time.

I'm still betting pump...

 

[koda2000]

@pcrussell50
Again, replace your fuel pump.

 

[pcrussell50]

@pcrussell50
Again, replace your fuel pump.

Yeppers. That's the plan.

This morning, 21degF and cloudy at about 0900, it wouldn't start no matter how many times I primed it. Then about 11:30 the sun had come out and it was about 28degF and it started right up. First crank. :/

-Peter

 

[koda2000]

Yeppers. That's the plan.

This morning, 21degF and cloudy at about 0900, it wouldn't start no matter how many times I primed it. Then about 11:30 the sun had come out and it was about 28degF and it started right up. First crank. :/

-Peter

More than likely your not priming anything. Are you hearing the fuel pump hum for about 2 seconds every time you turn the key to ON? My guess is not, not that it really matters. I've had 4-5 Explorer/Mountaineer fuel pumps fail in exactly the same way. As long as the temps were around 60F or above they started fine. If the temps were below 50/60 degrees I'd be lucky to get them to start with multiple attempts. If it was really cold out, there was no way they'd start. It's because the fuel pump motor's brushes are worn, or the springs that push the brushes against the motor's commutator are weak. When it's cold outside the metal springs contract and that's just enough for the fuel pump to not work.

 

[donalds]

We have these fuel pumps down to a science lol

 

[koda2000]

We have these fuel pumps down to a science lol

Yep. If there's a single area of the Gen II Explorer/Mountaineer in which I consider myself an expert (and frankly there are quite a few others) it's in diagnosing and replacing fuel pumps. I can drop a fuel tank and replace a fuel pump in 90 mins or less and that includes putting my tools away.

 

[ducrnd]

Yep. If there's a single area of the Gen II Explorer/Mountaineer in which I consider myself an expert (and frankly there are quite a few others) it's in diagnosing and replacing fuel pumps. I can drop a fuel tank and replace a fuel pump in 90 mins or less and that includes putting my tools away.

I would like to pick your brain for a minute if I could. I have a 01 explorer 4.0sohc. Recently I have been having trouble starting it in the morning or after it sits a few days. sputters and coughs, like it is not getting fuel. but once started ,it runs like a champ. A new fuel filter was installed, same issues. I have noticed that the temp gauge only goes up about a 1/4 of the way.I get great heat, but that has never done that before. It was always middle of the gauge. Any direction you could point me ?

 

[koda2000]

The Job 1 SOHC's tend to develop air leaks between the upper and lower intake manifolds and the lower intake manifold and the heads. This can make them run like crap when first started and, if bad enough, turn on the CEL with ODBII P0171/0174 lean codes. This is exacerbated then it's cool/cold outside as the parts contract with the cold and make the leaks worse. As the engine warms up parts expand and the leaks close up. Then the engine may run fine. Changing the O-ring gaskets on the intake usually solves the problem. With age the O-ring's shrink and become hard and brittle. Most older SOHC engines need to have the intake manifold gaskets replaced for this reason. The Job 2 SOHC engines eliminated the 2 piece intake manifold and used fatter O-rings on the bottom, so they are not so prone to this problem.

How many miles do you have on your fuel pump? I've found that they tend to start having intermittent starting problems between 175K-200K. This typically shows up during cool/colder weather, but they may work great for years during warmer weather. If you have anywhere near 200K on your fuel pump you should replace it, because you're living on borrowed time.

You low temp gauge reading is likely due to a bad thermostat. When's the last time it was changed?

 

[ducrnd]

The Job 1 SOHC's tend to develop air leaks between the upper and lower intake manifolds and the lower intake manifold and the heads. This can make them run like crap when first started and, if bad enough, turn on the CEL with ODBII P0171/0174 lean codes. This is exacerbated then it's cool/cold outside as the parts contract with the cold and make the leaks worse. As the engine warms up parts expand and the leaks close up. Then the engine may run fine. Changing the O-ring gaskets on the intake usually solves the problem. With age the O-ring's shrink and become hard and brittle. Most older SOHC engines need to have the intake manifold gaskets replaced for this reason. The Job 2 SOHC engines eliminated the 2 piece intake manifold and used fatter O-rings on the bottom, so they are not so prone to this problem.

How many miles do you have on your fuel pump? I've found that they tend to start having intermittent starting problems between 175K-200K. This typically shows up during cool/colder weather, but they may work great for years during warmer weather. If you have anywhere near 200K on your fuel pump you should replace it, because you're living on borrowed time.

You low temp gauge reading is likely due to a bad thermostat. When's the last time it was changed?

247k milage. and the thermostat was replaced ?? 2 years ago. but I get great heat out of it, so Im wondering if thats the thermostat or sensor.?

 

[ducrnd]

247k milage. and the thermostat was replaced ?? 2 years ago. but I get great heat out of it, so Im wondering if thats the thermostat or sensor.?

Also , "the JOB1" and the JOB 2.???

 

[donalds]

Also , "the JOB1" and the JOB 2.???

Same engines different intakes and build dates

 

[BTR]

Same engines different intakes and build dates

I have a 2000 Explorer XLT, 4.0L, SOHC, 4-Door, 2WD, 5-Speed Automatic. How do I determine if my engine is a “Job 1” engine, or a “Job 2” engine? Can you provide some specific technical data (build dates, VIN letters, etc.) that I can use to make the determination? Thanks.

 

[donalds]

I can't but @koda2000 May be able to help

Or you could just post a pic

 

[koda2000]

247k milage. and the thermostat was replaced ?? 2 years ago. but I get great heat out of it, so Im wondering if thats the thermostat or sensor.?

Without knowing exactly how hot your coolant is there's no way of knowing whether your t-stat is working properly. The easiest way to tell is by using a laser temp measuring device, or ForScan, but a meat thermometer stuck in an open radiator will also give you an idea. I bought a '00 Mountaineer who's temp gauge barely moved off COLD during February when I bought it, yet it seemed to put out good heat. It turned out the t-stat was stuck open and the gauge reading was accurate. Messing with the temp sender or sensor on the top of the t-stat housing on an old SOHC can cause coolant leaks because the brass inserts break loose of the plastic housing. Best to check out the thermostat performance before changing parts.

At 247K you are way overdue for a new fuel pump (by 100,000 miles). That's likely the cause of your hard starting problems. All of my 6 Explorers/Mountaineers started having starting problems between 175K-200K. I only use Bosch fuel pumps (PN 69128) and have had great results with them. If you just replace the pump yourself it'll only cost you around $50 + the cost of a new strainer sock and fuel filter.

 

[koda2000]

I have a 2000 Explorer XLT, 4.0L, SOHC, 4-Door, 2WD, 5-Speed Automatic. How do I determine if my engine is a “Job 1” engine, or a “Job 2” engine? Can you provide some specific technical data (build dates, VIN letters, etc.) that I can use to make the determination? Thanks.

Aluminum valve covers with the oil fill cap on the driver's side = Job 1. Black plastic valve covers with the oil filler on the passenger side = Job 2. There's no real difference between Job 1 and Job 2 SOHC engines, but the Job 2's use a 1-piece intake with better sealing O-rings and the PCV valve is located in the rear of the driver's side valve cover. The log blocks are interchangeable from 1998-2010.