2001 Explorer stalls has lean codes

[cb75]

Hello, Having issues with my '01 Explorer 4WD, 4.0 V6 automatic. It started stalling a week ago, got off the interstate and made a right turn when it just quit with no warning. I put it in neutral and it started right back up. Drove another couple miles to work, came down a long, gradual hill to my job and it stalled again.It started right back up again. After work I had kinda forgot about it and left for home. Got to a red light where i sat for 6-7 minutes, light turned green and when I went to take off, it started sputtering and died. This time I had to sit there for 40-60 seconds before it would start again. Check engine light had already been on due to the speedometer not working, so when I got home I retrieved the codes.

Had P0171 and P0174 for lean condition left and right banks. So Far I've: Replaced the plugs and wires, replaced the fuel filter, tested fuel pressure- 60psi, cleaned the mass air flow sensor, checked the MAF voltages using 2000 StreetRod's write up. They checked fine, Replaced the IAC, Replaced a couple faulty vacuum hoses, Resealed upper and lower intake manifolds.
After all this it seemed to idle much smoother and lower and for a while I thought I had it fixed. But, next day it started stalling again. My questions are: could the lean codes cause a stalling issue? and what would you all reccomend my next move be?

Also, it was only stalling after sitting at a red light and taking off, or when coming off the throttle when going down a hill, or approaching a stop. Today however it quit while doing around 65mph down the highway. I was cruising along, went to accelerate, when it started acting up and wouldn't respond to throttle. I was able to coast to the shoulder where after 2-3 attempts it restarted and I made it to work.
I'm not gonna drive it again until I figure it out. I borrowed a nice Snap On scanner and will be working on it tonight. Just wondering again about the lean codes causing this.
One more thing, I just checked the codes again and only the P0174 is present.


Thanks for taking the time to read my post, and for any advice you may have.

 

[Turdle]

Aha!
going down hill it stalled.

less than or just over 1/4 tank of fuel?

The lean codes for both banks indicates either too much air or not enough fuel. earlier this year on a long trip through colorado coming down a steep mountain pass, we experienced a similar occurrence with around 3/8 tank of fuel indicated. Climbing previous hill may have caused a artificially high reading though. However, I did not get any check engine lights, she just died. Until I started it again and we went uphill. It ran great. being from Kansas I got confused--



The fuel pickup is toward the rear of the tank. When all the fuel sloshes forward, the fuel pump goes dry.

Edit.
It is common for the v6 engine to develop leaking lower intake manifold gaskets, and or pcv valve system connections. These will also trigger the codes you posted.

An intermittent fuel pump might also be the issue.

 

[410Fortune]

I agree with Jon 110%!!!

However they said they re sealed the intake plenum gaskets, upper and lower
Lean on both banks indicates like Jon said, too much air in the exhaust.
This means that the computer has opened the fuel injectors as much as it can and still there is too much air in the exhaust. So you have either air entering the system after the MAS (mass air flow meter) or you have a weak fuel pump.
Check intake tube for leaks, check intake manifold itself for leaks or cracks, check fuel rail PSI
Because it is on both banks we can rule out a leaky exhaust manifold or a single cylinder leak/misfire.

171 and 174 = It is almost always leaky intake gaskets or a weak fuel pump / fuel starvation issue (fuel pump relay/low fuel in tank)

 

[cb75]

Thanks for the quick replies!
Originally I had both 0171 and 0174 codes. I deleted them after working on it a few days ago. After 3 days of driving, only the P0174 code came back. Also sometimes when it stalls it's not after coming down a hill. Although now that I think about it, the problem does happen more often after coming down a hill (sometimes a very gradual, long grade) But it has done it at a stop light that's at a very level section of road.
Would the problems that cause a lean code cause the engine to stall? Everything I've read about 0171 and 0174 never mentioned stalling.

I replaced the fuel pump back in March/April when I first started driving the Explorer. I've checked fuel pressure at the shrader valve on the fuel rail and had a steady 60psi. I will have to get a longer hose to check it while driving. It wouldn't surprise me that a several month old pump was weak, as I have seen other newer pumps fail.
I'm gonna get back to it tonight after work. Borrowed a nice Snap On scanner to use. Hope that will help pinpoint the problem. Getting a bit frustrated as this is currently my daily driver.

 

[david4451]

This sounds like split hose inside the fuel tank or a weak fuel pump. Splits in hoses inside the tank can be difficult to see, so examine very carefully. On my ST I had split hose which gave similar effects as you are having. Especially so with lower fuel in tank.

 

[cb75]

This sounds like split hose inside the fuel tank or a weak fuel pump. Splits in hoses inside the tank can be difficult to see, so examine very carefully. On my ST I had split hose which gave similar effects as you are having. Especially so with lower fuel in tank.

That's something I never thought of. I have seen that happen on Bobcat skid steer loaders. The pick up tubes would split or break and once the fuel level got to below a certain level it would act like it ran out of fuel.

Thanks for the suggestion david4451, I'll definitely check that, sucks because I just put $30 worth of gas in it this afternoon.
Thanks again, I'll let you know what I find.

 

[cb75]

Well, you guys nailed it I believe. I mentioned in my last post that I had put $30 worth of gas in it. Since that time I did not have it stall or stumble.
Went ahead and hooked up the scanner on Friday night and checked everything it would check. Drove around while watching different values for fuel trims, O2 sensors, voltages, and temperatures. Admittedly a lot of the numbers were Greek to me, but it all appeared to be normal. That's when I got to thinking about the fuel pump and pick up tube. The last couple times I had it stall, I was below a quarter tank. I was now just at a half tank. So after work Saturday I went and added more gas to around 3/4 tank. Drove it home Saturday evening and this afternoon with no problems.

I plan on ordering a new pump assembly and replacing it next weekend. I will report back with my findings.

Thank you all so much, you guys know your explorers!
I guess all the work I did was needed anyway. The plugs I removed were worn to .100 when they should've been .054! The fuel filter probably hadn't been changed for years if ever. And the intake o-rings were flat and needed replaced. I'm still going to chase the lean code. Bought a new pcv valve, and need a few more new vacuum hoses. Thinking about also doing the timing chains, guides, and tensioner as I noticed what I think may be the beginning of a slight rattle. I had a 96 explorer that had a chain fail and skip time which led to me trading it for a 97 V8 explorer.

Thanks again! You all are an invaluable asset to Explorer and Ranger owners!

 

[Turdle]

in these trucks I would consider 1/4 tank empty. I never run mine below 1/4 tank.

 

[IronCurtain]

^100% agree...My 95 started stalling on me, first was when I went thru a sharp s turn, then when I would stop at a light, then finally died coming off the highway. Fuel pump code. Replaced fuel pump, but started getting those same exact lean codes. Turns out it was a bad *new* fuel pump. Replaced it, and it started dying AGAIN a couple weeks later. I finally learned that I was letting my tank get down to almost empty, and only putting $5 or $10 in it.

Ever since, I've kept it above 1/4 tank, and it hasn't had a problem since. Been almost 2 months. Was extremely aggravating to say the least . Also don't bother with the cheap ones. Get a nice one.

 

[sport40]

If you install all correct factory parts it wont starve below 1/4 tank of fuel, i can run mine till red light comes on and drives just fine, its a 2001 sport.