LR4 Fuel Issues after alternator fail

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Mitchel3408

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Hello all, my wife’s LR4 is giving P0627 and P018B codes.

Background: The alternator failed the other day while driving and we towed it home and I replaced the alternator. The charging system light stayed on and I saw 13.6v at idle. I ordered another new alternator and told her to drive it until it came in. Before it came in the truck died in the middle of the street and gave the P0627 code. I towed it home and got the new alternator in and saw 14.8 volts. No codes came in while it idled, I took it around the block and as I backed into the drive way it died and would not restart. I got the P0627 and P018B codes.

I’m assuming that the first alternator I put in damaged something electrical in the fuel system, pump perhaps? But the P018B code is throwing me off. I read the fuel pressure at idle after the second alternator change and saw ~420 psi.

My thoughts are the low pressure fuel pump is bad, the controller/relay is bad, or a sensor is bad and shutting off the pump.

Anything thoughts or tests to run would be appreciated! I hate to just start throwing parts at it.
 

itsaguything

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I can’t buy your hypothethis. These are independent, protected systems.
And as I know nothing of your particular vehicle, it is difficult to weigh in.

Does your vehicle incorporate a BMS. Do you have the correct (and healthy) battery for your vehicle?
What complete set of DTCs are thrown, please?
 

Mitchel3408

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I can’t buy your hypothethis. These are independent, protected systems.
And as I know nothing of your particular vehicle, it is difficult to weigh in.

Does your vehicle incorporate a BMS. Do you have the correct (and healthy) battery for your vehicle?
What complete set of DTCs are thrown, please?
Well maybe I’m wrong and the fuel system failure is unrelated to the alternator failing/bad alternator install. But seems unlikely to me to happen right after the alternator issues.

Yes it has a BMS, it has the correct battery (New AGM installed within the last year)

The codes I listed are all that are showing, see attached photos.
 

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MellonRover

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I used a napa rebuilt in a pinch ( 4 hours from home) and mine threw code for secondary pump when alternator spiked. Same as you, stalled and wouldn't start. After about 30 min cool down, it acted normal. Replaced with new JLR alternator and no problems. Wonder if you are seeing similar. Where was the alternator from? New or rebuilt?
 

Mitchel3408

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I used a napa rebuilt in a pinch ( 4 hours from home) and mine threw code for secondary pump when alternator spiked. Same as you, stalled and wouldn't start. After about 30 min cool down, it acted normal. Replaced with new JLR alternator and no problems. Wonder if you are seeing similar. Where was the alternator from? New or rebuilt?


Oh interesting. The first alternator I installed was a Bosch rebuilt. The second one I put in was a new Denso alternator.
 

itsaguything

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Well, the Denso SC2 is the original generator. And compliments of the PCM, the output is variable, by design.
But I still can't buy that affected the fuel charging system.
Insufficient voltage will ill affect most modules. Out of interest, with the vehicle not running nor a battery charger not attached for at least 6 hours, and with everything off, what is the voltage reading of the battery?

Incidentally, have you seen the workshop manual?
 
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Mitchel3408

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Well, the Denso SC2 is the original generator. And compliments of the PCM, the output is variable, by design.
But I still can't buy that affected the fuel charging system.
Insufficient voltage will ill affect most modules. Out of interest, with the vehicle not running nor a battery charger not attached for at least 6 hours, and with everything off, what is the voltage reading of the battery?

Incidentally, have you seen the workshop manual?
I charged the battery before starting it yesterday (first time running after installing the denso) and battery was 12.6 volts. I drove it around the neighborhood yesterday and then cracked it about 30 seconds after it died. Haven’t touched it since then. I just check it after sitting for 24hrs and it’s 12.2v. Which might be from the short drive and cracking but that seems like a pretty good drop.

I have not seen the shop manual.
 

Mitchel3408

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I just tried to start it up again, and even after sitting it still cranked like it had no fuel and refused to fire. I’m going to get a pressure gauge and check the fuel pressure at the low side tomorrow.
 

Mitchel3408

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A reading of 12.2 is a battery at about 30% capacity. Not enough to power up all of the modules of the vehicle.
See https://www.varta-automotive.com/en...icle-details/car-battery-testing-instructions
Gotcha. Well I guess I’ll charge it up and test it at Autozone. My trickle charger said it was good but has no AGM setting like described in the link. Seems like it shouldn’t have dropped so quickly on a fully charged battery. Lucky it’s still under warranty if it is bad.
 

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