I've got a track day coming up in April, and have recently been reading up on the fuel starvation issues that E36s experience. I'm assuming this is not an issue only experience by M3 drivers (my car is a 325). Is this more common for those running R-compounds, because of the increased cornering forces?

Basically, with my setup (consult sig), on RE01Rs, should I be prepared for fuel starvation, and bring enough fuel to keep the tank above 1/2 throughout the day?

The track is Autobahn Country Club, full course.

It's not just an M3 problem as far as I know, but if your car is early enough build you won't experience it. My 11/92 build 325i can run to the light before I get any hiccups on track, with the stock fuel pumps.

-tammer

I don't think the difference in cornering forces from tires is much of an issue. Tracks with long sweepers will create more of a problem. The more the stock fuel pump tries to move fuel from the non-pump side (left) and sucks air in the process the worse the problem gets. At it's worst I'd get starvation when nearing 1/2 tank (OEM pump was starting to die). Prior to that it wasn't a problem until I was nearing 1/4 tank.

Bimmerworld dual fuel pump kit solves the problem nicely.

Jay

I can confirm that non-m3's have the problem.

If you are going to experience a problem at Autobahn, it will be on the last, long sweeper on the North track,as you enter the start / finish straight. No problem for my e36 race car as it has the dual pickups, but my e46 street / track car will hiccup if it gets down to a 1/4 tank.

Steve E.

If you are going to experience a problem at Autobahn, it will be on the last, long sweeper on the North track,as you enter the start / finish straight. No problem for my e36 race car as it has the dual pickups, but my e46 street / track car will hiccup if it gets down to a 1/4 tank.

Steve E.

Thanks, good to hear with someone with experience at ACC.

Thanks for all the info, everyone! Much appreciated. I'll bring a little more fuel than usual, just in case.

Your 93 MY car is early enough that there should be no problem.

Neil

NeilM,

Good to hear. Was the fuel pump design changed at a certain year?

For what it is worth, my 1993 325is (built in Sept. 1992) will go to empty without a hiccup on track. Stock fuel pump.

If you are going to experience a problem at Autobahn, it will be on the last, long sweeper on the North track,as you enter the start / finish straight. No problem for my e36 race car as it has the dual pickups, but my e46 street / track car will hiccup if it gets down to a 1/4 tank.

Steve E.

+1. Turn 9 on the North course is THE corner that motivated me to get the dual pump setup from bimmerworld. Have not had the starvation issue since. :D

For first track day or first time driving autobahn, I would not worry about it. Keep the tank atleast 1/3 full and no problems.

What group you running with? I'll be there the 28th with AMS.

It'll actually be my third time at Autobahn, second time on full course, first time with my 325, though. I had a Miata previously.

And I'll probably be working tech on the 28th, I work for AMS. When I see your car come through, I'll be sure to say hello!

Sounds good, see you there!!

NeilM,
Good to hear. Was the fuel pump design changed at a certain year?

Sometime in 94 I believe. That may vary between different E36 models though. Technically the issue isn't with the fuel pump itself, but with the siphon system that transfers returned fuel from the driver side of the saddle tank to the pickup/fuel pump on the passenger side. BMW switched from an external transfer line to one inside the tank, which while it simplifies the plumbing, turned out not to work as well under track use conditions.

The effect certainly does vary with both R compound tires and driver skill level. In my early days of track driving I could run down to around the quarter tank level before experiencing fuel starvation in right-hand sweepers. As time went on and my cornering g's increased I could barely go below a half tank. Some cars also seem to be affected more than others.

Since I have a later model year car I installed the Bimmerworld dual pump system. Problem solved: I can run right down into the reserve light zone.

Neil

I guess it depends on the track also. I never had any fuel pickup issues with my 1993 325is except for the toe of the boot at Watkins glen. Had to keep fuel above 1/2 a tank to be able to drive the course. Bought the duel fuel pump setup from Bimmerworld. Now even with the light glowing, I don't have any pickup problems.

my early '94 build had extreme fuel starvation on long right hand corners with R comps before fitting duel pumps

I experienced quite a bit of fuel starvation at Buttonwillow this past weekend. I have been to that track 5 or 6 times before, and never had a problem. However, this was my first time with the S50B32. It started happening slightly at 1/2 talk, and by the time I got down to 1/4 tank, it was ridiculously frustrating. Every single right hand turn gave me problems. As soon as the car would straighten out, the car would take off very quickly. :rofl

When I get some more time, I plan on investigating a pair of Walbro fuel pumps, and possibly a baffle of some sort.

I experienced quite a bit of fuel starvation at Buttonwillow this past weekend. I have been to that track 5 or 6 times before, and never had a problem. However, this was my first time with the S50B32. It started happening slightly at 1/2 talk, and by the time I got down to 1/4 tank, it was ridiculously frustrating. Every single right hand turn gave me problems. As soon as the car would straighten out, the car would take off very quickly. :rofl

When I get some more time, I plan on investigating a pair of Walbro fuel pumps, and possibly a baffle of some sort.

Bimmerworld dual fuel pump kit will do the trick. As your OE fuel pump gets worse it starts happening at a higher level. Same happened to me. Got to a point where I'd have to keep more than 1/2 tank in the car to avoid starvation.

Jay

Same here. NP's at all last year. Now with a faster setup, I can't accelerate out of a long-ish right hander with anything less than 1/2 a tank. And yes, I installed a larger fuel pump not to mention 8an fuel lines.

Dual pumps going in tomorrow night.

Don

Bimmerworld dual fuel pump kit will do the trick. As your OE fuel pump gets worse it starts happening at a higher level. Same happened to me. Got to a point where I'd have to keep more than 1/2 tank in the car to avoid starvation.

Jay
I already have a Walbro high pressure fuel pump, so wouldn't it be a little unnecessary to buy an entire kit when I only need half?

I already have a Walbro high pressure fuel pump, so wouldn't it be a little unnecessary to buy an entire kit when I only need half?

If it's the one in the car now there's a good chance it's toast. If it's on the shelf and you want to add another and can fab up the plumbing it'll probably work.

Jay

If it's the one in the car now there's a good chance it's toast. If it's on the shelf and you want to add another and can fab up the plumbing it'll probably work.

Jay
The one in the car only has 4k miles on it. :help

You need two fuel pickups in an e36 tank to prevent starvation. How you go about doing it is up to you.

Bimmerworld's kit is plug and play and works fantastic, even in turn 2 at Willow Springs with the low fuel light on (lap after lap).

Interesting thread. I had my first track day last month at Road Atlanta and saw no problems with my M3 all the way down to when the light came on. I have a similar setup to the OP with Azenis instead of RE-01Rs. Turn 12 should cause fuel starvation in an M3 from all I've read in the thread...or am I mistaken?

Interesting thread. I had my first track day last month at Road Atlanta and saw no problems with my M3 all the way down to when the light came on. I have a similar setup to the OP with Azenis instead of RE-01Rs. Turn 12 should cause fuel starvation in an M3 from all I've read in the thread...or am I mistaken?

No offense but as a noob you probably aren't pulling as many G's for as long a period of time as someone with more experience, better suspension/alignment and stickier tires.

In the stock configuration the fuel pump will suck air as it's trying to pick up fuel that's not there because of the side loading. The longer the fuel pump has to work this way (I'm talking events, not minutes) the worse it gets until it becomes very apparent. That's why no apparent problems one year and the next you can't get below a half tank.

Jay

The one in the car only has 4k miles on it. :help

How many of those are track miles? The pump sucks air in track conditions. The more it does that the worse it performs.

Jay

No offense taken :) I know I'm a noob and understand what you're saying. I was just thinking that from what some people were saying, I could be at 1/2 a tank and see a problem with the fuel light. I see that you're talking more over time this becomes an issue as the pumps start to wear prematurely. Thanks Jay, that makes more sense!

The one in the car only has 4k miles on it. :help

You sure are having a lot of problems with this car...bad karma?

My '95 M3 starved at 1/2 tank on turn 2 at Roebling on it's maiden run. Called Bimmerworld. Problem solved. As stated, they have a sweet kit that's plug and play.

How many of those are track miles? The pump sucks air in track conditions. The more it does that the worse it performs.

Jay
Only 3, 25 min sessions at Reno-Fernley. I did 4, 25 minute sessions at Buttonwillow this past weekend, and it started doing it on my second session. So I dunno. :dunno

You sure are having a lot of problems with this car...bad karma?
Seriously. Someone backed into it on Monday morning and forgot to leave a note. The nose panel is dead and the cf hood is buckled.

I don't think I have bad karma, especially since I continually go out of my way to help people, and I'm pretty damn courteous while driving. Either way, it sucks. :(

e30s and e36s suffer a lot from fuel starvation, depending on tracks. This weekend at Calabogie, many racers and DE drivers experienced hiccups even with over half tank. Major elevation changes and big sweepers caused the problem. The solution is an anti surge tank, most likely installed where the fuel filter currently resides, or in the engine bay with a supplementary pump. Racers with fuel cells will put it in the trunk. I guess something similar can be done on e36s. Surge tanks with sufficient volume (0.6 to 1.0 litre) will allow the motor to run 100%, even with the primary pump continuously sucking air for over 45 seconds.

but if your car is early enough build you won't experience it

Where is this from? What's the logic or information behind this please...

I'd like to know the specifics... is it merely a fuel return line change or more?

Where is this from? What's the logic or information behind this please...

I'd like to know the specifics... is it merely a fuel return line change or more?

It's a design change that BMW made in the siphon tube arrangement that transfers fuel to the pickup (right) side from the return (left) of the saddle tank. Earlier cars have an external crossover line, later cars (late 94-ish?) an internal one.

It's not apparent to me why this change has the effect that it does — but it does. A friend of mine who is an extremely rapid driver can run his 93/94 (I forget) 325i track car down to very low fuel levels without a hint of starvation. My 96 M3 would have a problem at not much under a half-tank until I installed the BimmerWorld dual pump setup several years ago.

And just to further confuse the picture there's also car-to-car variation even with the same stock setup. Go figure.

Bottom line: if you do experience fuel starvation, the BW kit fixes it completely. If you don't, then sit back and enjoy your good fortune.

Neil

lucky for me I have a '92 then.

thanks for the info!

Other modifications could affect what's happening as well. With the stock M42 in the ti (4/95), I could run down to the light before starving, but after installing the M52, it would starve at a half tank...same fuel pump, same return, same tank.

Still the same answer though - get the BW kit...lose 40lbs of fuel you have to carry. :)

I fixed my fuel starvation issues. I placed a secondary pump in the drivers side and it pumps over to the passenger side. I have a HP pump in the passenger side already so it didn't make sense to me to have 2 pumps going to a "T" and also a "T" in the return. My return goes to the drivers side pod. I'm told this is the BW solutions as well? Dunno. Made sense to me to do it this way....I'm pretty pleased with the results.

Only issue is I have to remove the internal siphon or move it because it interferes with the gauge float on the drivers side...hence my fuel readings are skewed.

Don

I'm told this is the BW solutions as well?

Yes, the BW kit supplies a replacement passenger side pump (early pattern with external return port) plus a new driver side pump that's used to transfer returned fuel to the pickup side. However the in-tank transfer pipe is eliminated in favour of an external version. Some installation finagling is needed to get the driver side level sensor float to travel freely, but once you get it right it does.

Neil