[MagnusT]

Has anyone had problems with fuel starvation on track?

It's a classic problem with both M3 E36 and E46, I've experienced both in my own cars. Long right bends on sticky track tyres, where you are on full throttle a long bit can result in fuel starvation as early as just under half a tank in worst case scenarios.

Last week my M2 stopped running after such a bend when at just below quarter of a tank. The big difference was that it didn't go back to running properly after second or two as the earlier cars do. My M2 coughed and ran unevenly for ten seconds and then stopped. Trying to restart it just resulted in it doing exactly that again. It wasn't drivable at all and was towed.

The cars fuel gage showed just under a quarter of tank of gas. The odd thing is that the shop checked the system and the left half of the tank reported 14 liters but the right half where the pickup pump is had 0 liters! The log showed errors on fuel pressure and indicated that the fuel pump should be replaced, so they did. But they did manage to get it started by simply filling it up a bit. I didn't try that myself since the fuel gage said there was a lot of gas left. Stupid me...

Haven't been able to test it yet but I know of another M2 that had this problem that was fixed with a new pump.



The important question is why didn't the pump that pumps the gas from the left half to the right do it's job?

[DanG]

Originally Posted by MagnusT

Has anyone had problems with fuel starvation on track?

It's a classic problem with both M3 E36 and E46, I've experienced both in my own cars. Long right bends on sticky track tyres, where you are on full throttle a long bit can result in fuel starvation as early as just under half a tank in worst case scenarios.

Last week my M2 stopped running after such a bend when at just below quarter of a tank. The big difference was that it didn't go back to running properly after second or two as the earlier cars do. My M2 coughed and ran unevenly for ten seconds and then stopped. Trying to restart it just resulted in it doing exactly that again. It wasn't drivable at all and was towed.

The cars fuel gage showed just under a quarter of tank of gas. The odd thing is that the shop checked the system and the left half of the tank reported 14 liters but the right half where the pickup pump is had 0 liters! The log showed errors on fuel pressure and indicated that the fuel pump should be replaced, so they did. But they did manage to get it started by simply filling it up a bit. I didn't try that myself since the fuel gage said there was a lot of gas left. Stupid me...

Haven't been able to test it yet but I know of another M2 that had this problem that was fixed with a new pump.



The important question is why didn't the pump that pumps the gas from the left half to the right do it's job?

Seems like a simple answer: the fuel pump was broken. Should it had broken: no. But I guess that is what a warranty is for.

[MagnusT]

The thing is that the pump pumping from the left tank half to the right tank half is passive not electric. Can't see how it can break.

The electric pump pumping fuel to the engine was obviously sucking air since it only picks up from the right half which was empty.

[eeyang92]

I've heard stories about this so I always try to keep my fuel above 1/2 (generally enough to do 2 sessions).

[alscks0414]

I believe BMW had LPFP recall on variety kinds of their model through 16-17 production. (I could be wrong but many of 3/4ers and 2ers were affected, my dealer mentioned that some M2s were affected last year as well)

My question is if you have tuned yours.

Dinan suffered the same issue with their S2 (stage 4) tune package, offering LPFP kits to replace the OE to comply the low gas in the tank to supply the demand of their tune fuel requirement.

[MagnusT]

100% stock. Early -16 build.

What's LPFP?

[Ex-MINI]

This has been reported before, cars having issues, going into limp mode, especially on track when the gas level starts to drop and has fuel pickup issues

http://f87.bimmerpost.com/forums/sho...9&postcount=18

[Ex-MINI]

Originally Posted by MagnusT

100% stock. Early -16 build.

What's LPFP?

Low pressure fuel pump

[MagnusT]

Thanks.

I'd like to understand how the system works, mainly the non electric pump pumping from the left tank half to the right half. Anyone have any pointers to info, web page or something?

And also, anyone know how Dinans kit solved the problem?

[alscks0414]

Originally Posted by MagnusT

Thanks.

I'd like to understand how the system works, mainly the non electric pump pumping from the left tank half to the right half. Anyone have any pointers to info, web page or something?

And also, anyone know how Dinans kit solved the problem?

I believe it is explained on their website.
https://www.dinancars.com/product/r4...eries=&mid=M2/

[Tano]

Originally Posted by MagnusT

Thanks.

I'd like to understand how the system works, mainly the non electric pump pumping from the left tank half to the right half. Anyone have any pointers to info, web page or something?

And also, anyone know how Dinans kit solved the problem?

Check the Fuel supply section of this pdf.

[alscks0414]

Furthermore,
If your car is bone stock and keep having this issue, bring her to your dealer.
Report the problem and let them deal with it.
My SA said that he had seen few cars fixed under warranty.

M cars are meant to be enjoyed on track. If vehicle fuel system cannot supply what stock car puts out, they should do something.

I believe this does not apply to all cars.

[ZM2]

The Dinan kit fixed it for me. I can run the tank almost dry now.

[MagnusT]

Thanks for all feedback!

Will check out that PDF fight now!


Sort of surprised looking at the few parts in Dinans upgrade kit that they fix this. Shame on BMW for not making it like that from the start.

[MagnusT]

Great PDF!

It looks like the passive "jet pump" is driven by the fuel flowing by in the T-connection. So if the flow stops, due to the electric pump sucking air, the passive jet pump will stop working. That's stupid...

I really wonder if E46 and E36 have the same design, they didn't behave like that IMHO.

[DrKevM5]

This happens to me every time I track at a long fast track. If you shut the car down and let it sit for 20 to 30 minutes it will reset itself. I have a DINAN stage four with the fuel pump upgrade and it still happens to me. The stock fuel pump cannot handle the demands of a high horsepower application. I've been working on a HPFP solution. Switching to stage III cures the problem at the expense of lower horsepower.

[MagnusT]

My car didn't reset. It sat for two hours and still wouldn't run. Actually, it sat for two days at the shop and didn't even start after that

Bit annoying to have to be towed off the track! This never happened with the E36 or E46, they'd just cut out for a second or two and then continue to run.

[M2guru]

Oddly, but thankfully, I let mine (2018) sit for about 1 minute (2 at the most) and it started right up like normal.

I started a 20-minute session just above half and it started starving at half and then gave the malfunction code at just under half. Went to the pits thinking it was something more significant. Shut it off (hot!). Looked around and didn't see anything glaring, so I started it up and it ran fine. Fortunately that was the last of 3 sessions that day (started with a full tank).

[MagnusT]

I'm very interested in who of you experienced this coming out of a long right turn with a lot of lateral g-forces and who were in som other situation but going full throttle.

Just to see if we have two different problems. One being general trouble supplying enough fuel under heavy load situations. The other one being g-forces moving fuel over to the left tank half in combination with the passive jet pump failing to fill the right half fast enough or at all.

[Tano]

Originally Posted by MagnusT

Great PDF!

It looks like the passive "jet pump" is driven by the fuel flowing by in the T-connection. So if the flow stops, due to the electric pump sucking air, the passive jet pump will stop working. That's stupid...

I really wonder if E46 and E36 have the same design, they didn't behave like that IMHO.

Similar jet pump system worked in the earlier models too.
This method empties the left tank first. So if you have left fluid in the left tank but not in the right then this system is not working in your car. Maybe a blockage in the fuel line or something similar.

[paradoxical3]

Happens to me every single track day. Total bullshit for BMW to market an M car for the track that can't even make it through a complete 30min session with anything except an absolutely full tank.

[MagnusT]

Originally Posted by Tano

Similar jet pump system worked in the earlier models too.
This method empties the left tank first. So if you have left fluid in the left tank but not in the right then this system is not working in your car. Maybe a blockage in the fuel line or something similar.

What I can find is that E36s had a pressure regulator at the engine and a return line to the left tank half. Still missing info on the passive pump on them.