Low voltage and then stalling out.

[DeeeePIMPact]

Hello, I have a 2003 Ford Expedition, 4x4 5.4.

I have a problem when starting the truck that the voltage starts at 12.3 and continues to drop until the truck stalls out. I am able to start the truck again but it just dies in less than a minute after I do, again with low voltage. I am able to raise the voltage when I get on the gas but that does not stop the truck from eventually stalling out.

I have replaced the fuel filter and the battery. I have tried a different alternator being that my stock one is making a humming noise. Same result with both alternators. I have also preformed the "Big 3" wire upgrade to my truck.

I have been told by a mechanic a week or 2 before this started to happen that my starter is going bad and not engaging the first time. So when I go to start my truck it never starts right up on the first attempt, but as soon it fails at the turn of the key the first time I try again and it always starts the second time.

I do have a check engine light on with codes I just had read yesterday P-0420 & P-430 which I've been told are related to my catalytic converter because I've had all 4 of my o2 sensors replaced...

I also have a viper alarm that has the remote start and that never has a problem starting the truck.

I'm at kind of a loss here... I have read that when the starter is going out that sometimes the solenoid can short and sometimes cause these issues with these trucks. Is there any truth to this?

Does anyone know of any diagnostic tips or what the problem might be?

Thank you in advance!

 

[DeeeePIMPact]

maybe a bad tensioner?

 

[DeeeePIMPact]

Checked Fuse # 2 and #34 thinking it might be fuel pump related and both are fine... But the voltage going up and down I feel like is a flag. If I stay on the gas the car will stay running and the voltage stays up around 13.5 all the way up to 14 BUT before this would have no problem idling around 14.3-14.4 which makes me think the power fluctuation is related to the problem....

Recently when I get on the throttle in park I here the smallest squeak. I have recently replaced the idler pulley on the left side of the engine and like I said as of right now I have a new alternator installed.

 

[DeeeePIMPact]

It almost sounds like it's starving for fuel before it cuts out... but again the voltage dropping makes me think something being belt driven is causing the problem.

 

[DeeeePIMPact]

The screeching is starting to become more pronounced... Seems to happen when I tap on the gas. Leading me to me to believe tensioner.

 

[DeeeePIMPact]

I watched a youtube video that said if you spray the belt with water and the screeching gets worse than it's the tensioner. If it the screeching goes away the belt is misaligned. The screeching got WAY worse! When I sprayed it with water the screeching was nonstop and very loud. I just replaced the belt with a Gates one back in Nov-Dec 2016.

Can someone confirm this? Would a bad tensioner cause the truck to stall out if not pressing on the throttle?

 

[1997SCEBFEX]

could very well be your tensioner.
the vehicle will only run for so long w/o charging to the battery/system if the alternator is not operating properly resultant of a bad tensioner.
easy part to source and replace.

running: you didn't post mileage, thus suspect in the 100K range? has your MAF/Throttle Body been cleaned. How old is your Idle Air controller? Plugs & air cleaner too? Any chance you have bad gas? never hurts to run a good bottle of reputable cleaner through it.

sure others will chime in

 

[stamp11127]

Maybe you are overlooking the true cause of your problem. Low voltage is below 11 volts so your problem is what is causing the engine to die.
Remove the serpentine belt and spin all the pulleys including the ac clutch. A bad bearing in any of them will be noticeable.
Bad tensioners usually have a bouncing movement when the engine is running.

 

[DeeeePIMPact]

Thank you for the help guys. I think, HOPEFULLY I found the problem

After a couple hours of sleep I woke up and decided to unplug the MAF sensor just to see what would happen and the problem has went away. I just got done cleaning the MAF sensor with MAF sensor cleaner and letting it dry now.

I'll put it back in and update you with the results. Thank you again for all your help. Seems as if the squealing from the tensioner was a effect not the cause HOPEFULLY!

 

[docraymund]

You could do a voltage drop test to see if you have a wiring problem.

 

[DeeeePIMPact]

Thanks, the voltage drop test will be something I do today just to double check everything. I got the MAF sensor plugged back in and everything is fine. The voltage is at 14.4-14.3 at idle and the truck is having no problems idling. Again, thank you for the suggestions!

 

[DeeeePIMPact]

It seems as if the rough idle has returned. I tried to clean the sensor and it's still idling rough. The truck doesn't seem to stall out as it did before but the idle is rough and the voltage fluctuates between plus or minus .8 to .4 volts. Again I have the H.O. Alt on right now and the regulator doesn't connect to the alt causing check charging system light to come on.

The problem seem to come back on my drive to the gas station to fill up the tank..... I did take the battery cable off for an hour after I thought I solved the problem by cleaning the MAF sensor this morning...

Back to the drawing board....

 

[Big Brian]

go back to Stamp's post #8

you have a charging problem you need to sort out from what I am reading

 

[Bedrck47]

One thing I have noticed in all of this is That you state "Low voltage and then stalling out."

Now you mention that the "the rough idle has returned" and "The truck doesn't seem to stall out as it did before"

Have you checked for any vacuum leaks?

 

[DeeeePIMPact]

No I haven't checked for vacuum leaks. I did have a vacuum leak in the 4x4 system that was engaging the 4x4 in the front hub bearings. I replaced the 4x4 solenoid by the battery with 1 that had the plastic covering preventing water from getting in and still had the problem. I bypassed that solenoid and haven't had the problem with the 4x4 engaging since. That was about 4 weeks ago.


Other than that I know of no vacuum leaks, to my knowledge. BUT no I have not tested for them either.

 

[DeeeePIMPact]

I determined that the screeching was coming from the ribbed idler pulley on the right side of the engine. Replaced that and screeching is gone. I visually inspected the rest of the pulleys in between the rain we're getting and I don't SEE what I would call bad pulleys. The tensioner is moving a little up and down at idle but doesn't look like anything crazy. The pulley on the tensioner appeared to be spinning fine...

After I cleaned the MAF sensor the voltage has not dropped below 13.0 volts at all. Even though the idle is real rough and the voltage is fluctuating between .8 to .4 volts. it's usually between 14.5 to 13.7 lowest sometimes to 13.3....

I can not remove the belt right now and spin the pulleys because of 1.) the rain and 2.) I have stiches in my back right now and the further down I reach I can feel the stiches straining...

When I went to replace the ribbed idler pulley I had the manager at advance look at the belt system and the only concern he had was that the smooth idler I replaced a couple weeks back on the top left side of the engine can spin freely without relieving any tension from the tensioner.

He squeezed the belt while the car was off watching the tensioner move and it didn't seem to have any problems. BUT he did think it was weird that the smooth idler pulley on the top left side could spin freely with the tensioner not being touched....

 

[DeeeePIMPact]

The truck does not stall out anymore, since I cleaned the MAF sensor. The truck ran fine after I cleaned the MAF sensor, so I disconnected the battery to reset the check engine light . Came back connected it and went to get gas. On my way to getting gas is when I noticed the rough idle had returned. BUT again its just a rough idle and it doesn't stall out like it used too before I cleaned the MAF sensor.

 

[DeeeePIMPact]

during the rough idle the voltage is fluctuating between .8 to .4 volts usually between 14.5 to 13.7 lowest sometimes gets to 13.3.

 

[DeeeePIMPact]

another concern the manager had at advance was the regulator not being plugged in on the H.O alternator. He said when I unplugged the battery, the PCM or computer system might be having a hard time re-learning because of that regulator not being plugged.

I'm in the works of trying to figure out a way to connect the stock regulator wire harness coming from the car to the HO Alternator by having a pig tail custom made for the HO alternator.

 

[DeeeePIMPact]

BUT before I even had a rough idle I had this HO alternator on the truck and there was never a rough idle... BUT then again I never disconnected the battery to reset the check engine light either until now.....


Not trying to confuse anyone, just trying to give all the information I know.