Towing after misfueling scenario

capt_slow · 12-01-2022, 12:54 AM

I've been driving diesel cars for over a decade now and never once misfueled. But always wondered: if the car was misfueled and was caught early right at the pump, what would be the procedure to get it to a shop?

In order to put the car on a flatbed, the ZF8HP electronic unlock requires cranking the engine. Can't crank the engine because of gas in the tank and I'd imagine you can't pull the fuel pump fuse as that would run the HPFP dry.

Is the only option to get under the car and release the mechanical unlock?

Watsey · 12-01-2022, 02:17 AM

My understanding is that, yes, going under the car to engage Neutral mechanically is the only way in that scenario.

It's a ridiculous design.

Here in the UK I'd just insist that the recovery vehicle had a crane with specialist wheel cradles, or wheel dollies as a fallback option.

n00bkiller944 · 12-02-2022, 10:48 AM

Why cant you just turn the car to acc and put it in neutral? Guarantee the shop will do that once it gets to them anyway. Understood you dont want FP to run, but I imagine it wont be sucking the misfuel just priming for pressure. But I dont have any data to support that assumption

Enabled · 12-02-2022, 11:58 AM

It seems completely fine per BMW to pull the power supply to the low pressure fuel pump to do the electronic unlock procedure. See attached. It's not convenient, but it does work.

The HPFP will not have time to run completely dry, as its swimming in a lot of diesel.

capt_slow · 12-03-2022, 11:19 AM

Quote:

Originally Posted by Enabled

It seems completely fine per BMW to pull the power supply to the low pressure fuel pump to do the electronic unlock procedure. See attached. It's not convenient, but it does work.

The HPFP will not have time to run completely dry, as its swimming in a lot of diesel.

Do you happen to know where the fuse is on the F31, and which one? I'm hoping its right next to the battery instead of next to the FEM.

Enabled · 12-03-2022, 12:19 PM

Quote:

Originally Posted by capt_slow

Do you happen to know where the fuse is on the F31, and which one? I'm hoping its right next to the battery instead of next to the FEM.

Fuse 165 (20 Amp) on the rear fuse box in the trunk area, or unplug the electronic fuel pump module (EKPS) which is located behind the passenger rear seat side cushion thing.

Eddamoo · 12-06-2022, 05:37 PM

There should be plenty of diesel between the tank and injectors to start the car to pop it in N should you realize before the car dies on you. I think the diesel filter itself holds a good 300ml plus.

Enabled · 12-06-2022, 07:05 PM

The injectors don't spray until there is 200bar of rail pressure, so it may be questionable if it would start.
To be extra safe, disconnect the fuel rail sensor and crank all you wish. It won't start then even with all the fuel.

12-01-2022, 12:54 AM	#1
capt_slow Captain 556 Rep 906 Posts Drives: 2017 F31 328d Join Date: Oct 2013 Location: SoCal iTrader: (1) Garage List 2015 VW Golf SportW ... [0.00] 2017 BMW 328d xDriv ... [10.00] 2020 BMW i3 Rex [0.00]	Towing after misfueling scenario I've been driving diesel cars for over a decade now and never once misfueled. But always wondered: if the car was misfueled and was caught early right at the pump, what would be the procedure to get it to a shop? In order to put the car on a flatbed, the ZF8HP electronic unlock requires cranking the engine. Can't crank the engine because of gas in the tank and I'd imagine you can't pull the fuel pump fuse as that would run the HPFP dry. Is the only option to get under the car and release the mechanical unlock? __________________ 2017 328d xDrive Sports Wagon: Estoril Blue, Black Sensatec, M-Sport Pkg 2020 i3 Rex: Capparis White, Giga World
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12-01-2022, 02:17 AM	#2
Watsey Major General 6404 Rep 8,492 Posts Drives: F31 330D sDrive M Sport Join Date: Jun 2015 Location: On sabbatical. iTrader: (1)	My understanding is that, yes, going under the car to engage Neutral mechanically is the only way in that scenario. It's a ridiculous design. Here in the UK I'd just insist that the recovery vehicle had a crane with specialist wheel cradles, or wheel dollies as a fallback option. __________________ Current : F31 330sD, remapped, Ohlins Road & Track, Millway camber plates, Quaife LSD, Stoptech brakes + Pagid RSL1 pads all round, Weichers front strut brace, Eibach front & rear anti-roll bars, Michelin MP4S.
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12-02-2022, 10:48 AM	#3
n00bkiller944 Lieutenant 126 Rep 424 Posts Drives: '14 328d M Sport Join Date: Mar 2018 Location: Richmond, VA iTrader: (0)	Why cant you just turn the car to acc and put it in neutral? Guarantee the shop will do that once it gets to them anyway. Understood you dont want FP to run, but I imagine it wont be sucking the misfuel just priming for pressure. But I dont have any data to support that assumption
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12-06-2022, 05:37 PM	#7
Eddamoo Captain 390 Rep 808 Posts Drives: BMW 430dX Join Date: Apr 2018 Location: Sheffield, England iTrader: (0)	There should be plenty of diesel between the tank and injectors to start the car to pop it in N should you realize before the car dies on you. I think the diesel filter itself holds a good 300ml plus.
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12-06-2022, 07:05 PM	#8
Enabled Lieutenant Colonel 1406 Rep 1,799 Posts Drives: 328xd Wagon, M2 Competition Join Date: Jun 2018 Location: Houston iTrader: (0)	The injectors don't spray until there is 200bar of rail pressure, so it may be questionable if it would start. To be extra safe, disconnect the fuel rail sensor and crank all you wish. It won't start then even with all the fuel. __________________ -2014 328d Wagon, 8HP. Self-tuned, 270hp/430ft-lbs. -2019 M2 Competition MT, Alpine White. Self-tuned 560hp -2016 Mini Cooper S, MT. Many plans. Others: -E36 328is. 2000 Z3 Roady. 2003 VW Jetta TDI Manual. Estoril Z3M Coupe.
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