‘06 Dmax charging and fuel issue?

[K85 Octane]

Hey ya’ll, couple questions have come up while trying to deal with my Dad’s truck. (I borrow from time to time, just trying to help but I swear his stuff never fails to fall apart of me)

1) if you leave the truck parked for a week+ it will start, run for 5 seconds, and shut down. Only way to start it again is to pump the fuel primer ~10 times. Runs good after. Been happening a month now. What the what?

2) just yesterday truck hasn’t been charging the batteries. 190k miles
Batteries are fairly new. Yesterday was 90% not charging, 10% charging. So it works when it feels like it. Used for an hour this morning, maybe 40min charging. Pfff
Battery cables are clean and tight. Alternator rear stud good, red junction box clean and tight. Pulled added accessory wires off it. Multimeter confirms batteries and alt are all connected and while running it’s 12v, and less and less over the course of ~7 hours. Good thing there is no ignition. Disconnect small plug from the top of alternator, nothing changes. I will look at chassis ground later today. Where is the ECM ground?
Stupid ass new computer controlled alternators. But that confuses me some. The DR44/AD44 (can’t remember) in my blazer needs the computer to reach 14.x volts. Mine just runs at 13.5v fine without computer input. Why doesn’t the 2006 do that? Please help

 

[eric67camino]

1) Drain back on the fuel system usually indicates an air leak. If it's stock, there's no lift pump in the tank to feed the fuel forward, so you have to pump it up with the primer. I had my '01 do that and it was the fuel filter head. Did a rebuild kit and that fixed it on mine.

2) I would pull the alternator and have it tested. Could be failing intermittently. When checking connections, also check the starter end of the cables. I had that come loose and cause issues.

 

[fastazz81]

My alternator did that when it started going out.

 

[Fordum]

FWIW, my 2019 Honda Passport seems to have the computer controlled alternator. The car starts and runs fine. Even has the engine stop mode where is shuts off and recranks at stop lights and things.
I keep that turned off, but its on there.
So, it would seem having a well charged battery is very important. In stop and go traffic, the battery could easily fail to get topped off between starts.
I plugged in a USB charger module into the power socket to charge my tablet while I was driving, or phone if needs be. It has a readout on it that tells the input voltage, and the output current. I can tell when my tablet is charged due to the current being very low.

However, the other day, I glanced down and the readout said 12.5 volts. I was doing about 60, so it should have been around 14.5.
later, I saw 11.9.
Then, 13.7 and later 14.5. I had the car in the dealership for maintenance, and I asked them to check the charging system. I told them that the alternator was not putting out all the time.
They checked anyway, but told me about the computerized charging program.
Supposedly its programmed to slightly "cycle" the battery to lengthen its life.
Its an AGM battery, and I know they use different charging procedures than wetted plate ones, but this looks weird.

If yours has a similar system, you are going to see some strange voltages from time to time. Unless I can find some information that says intermittent charging either results in an improperly charged battery, or damage to it, I'm not going to squawk.
But, the first time it fails to crank, we are going to have another discussion.

 

[K85 Octane]

Well, couple nights ago I left it running because I was afraid it would start again. Left it for a while. When I got back in, the volt gauge was leaning more left than (enter who you want) I tried to move the truck but wouldn’t go. Trying 4L because it has a trailer full of dirt....that’s when the truck said enough was enough. Didn’t want to do anything, just idle. Shut it down and put it on a charger.
Swapping the alternator today. Hope that’s it.

 

[Russell]

Most likely will be a bad alternator. Not a whole lot else to go wrong with the charging system.

As mentioned above, the loss of vacuum on the fuel system will most likely be the fuel filter head.

 

[Burt4x4]

Hey ya’ll, couple questions have come up while trying to deal with my Dad’s truck. (I borrow from time to time, just trying to help but I swear his stuff never fails to fall apart of me)

1) if you leave the truck parked for a week+ it will start, run for 5 seconds, and shut down. Only way to start it again is to pump the fuel primer ~10 times. Runs good after. Been happening a month now. What the what?

2) just yesterday truck hasn’t been charging the batteries. 190k miles
Batteries are fairly new. Yesterday was 90% not charging, 10% charging. So it works when it feels like it. Used for an hour this morning, maybe 40min charging. Pfff
Battery cables are clean and tight. Alternator rear stud good, red junction box clean and tight. Pulled added accessory wires off it. Multimeter confirms batteries and alt are all connected and while running it’s 12v, and less and less over the course of ~7 hours. Good thing there is no ignition. Disconnect small plug from the top of alternator, nothing changes. I will look at chassis ground later today. Where is the ECM ground?
Stupid ass new computer controlled alternators. But that confuses me some. The DR44/AD44 (can’t remember) in my blazer needs the computer to reach 14.x volts. Mine just runs at 13.5v fine without computer input. Why doesn’t the 2006 do that? Please help

if you leave the truck parked for a week+ it will start, run for 5 seconds, and shut down. Only way to start it again is to pump the fuel primer ~10 times. Runs good after. Been happening a month now. What the what?

Your Fuel head assy is leaking/ letting air into the fuel line. Think of it when you let your finger off the straw end and all the milkshake spills out. Replace the fuel head assy . and your symptoms will disappear ... I have an '05 LLY and am on my third fuel assy. @ 340,000 is mile Original Owner!
DO It!
Burt