Are the US/Euro E36 fuel pumps different?

**jvit27** · 09-24-2007, 11:49 AM

Showing a lean condition in one of the banks and poor low-mid range power. Plugged in the diagnostic port to watch operating parameters(at idle) and o2 sensors don't like what their seeing. Motor almost feels like it's misfiring under 4500rpm on the road, pulls pretty good over that though.

Thinking the increase from 3.5 bar to 5bar could be straining the fuel pump?

Plugs are brand new, will be pulling them today to check.

**m3s3dave** · 09-24-2007, 01:02 PM

Jonathan

I can tell you they are different...but I can't tell you if that is the problem

**PenguinScotty** · 09-24-2007, 02:13 PM

Not sure what the differences are exactly, but, just to show you,

here is the Euro (Evo) pump assembly

and here is the US specc one.

To be honest, the 'Delviery Unit' seems to be what is holding the pump and on the outside, it doesn't really look different than the EU one

. For some reason though, the one for the Evo is a TON more expensive.

Hmm, maybe someone knows the exact speccs of the pumps.

If there really is a difference in the capacity the pumps can deliver, i can definitely see the car stumbling.
However, what does it feel like? Does it feel like a stumble, or a real misfire? Does it vibrate alot? Also, does it happen while driving or when sitting?

Sorry that i couldn't be more of a help here.

Have fun

**jvit27** · 09-24-2007, 02:19 PM

Originally Posted by PenguinScotty

Not sure what the differences are exactly, but, just to show you,

here is the Euro (Evo) pump assembly

and here is the US specc one.

To be honest, the 'Delviery Unit' seems to be what is holding the pump and on the outside, it doesn't really look different than the EU one

. For some reason though, the one for the Evo is a TON more expensive.

Hmm, maybe someone knows the exact speccs of the pumps.

If there really is a difference in the capacity the pumps can deliver, i can definitely see the car stumbling.
However, what does it feel like? Does it feel like a stumble, or a real misfire? Does it vibrate alot? Also, does it happen while driving or when sitting?

Sorry that i couldn't be more of a help here.

Have fun

Thanks, I couldnt find those on realOEM.

It feels like the car is chugging under 4000rpm. Starts to clear up over that.

It does vibrate a bit under acceleration, as well as deceleration letting off the gas. Doesn't happen during idle, only when driving.

The o2 sensors reported a lean condition at idle. You could hear the engine changing pitch while the ECU was trying to compensate for it.

**PenguinScotty** · 09-24-2007, 02:37 PM

Just throwing this out because i'm not sure, like i said, but the pump was running fine before the swap and all?
If yes, does the carbon-airbox (I think you have one, right?) use the standard MAF? Maybe that could also cause the problems.

Again, sorry, not sure what exactly it might be

**jvit27** · 09-24-2007, 02:54 PM

Originally Posted by PenguinScotty

Just throwing this out because i'm not sure, like i said, but the pump was running fine before the swap and all?
If yes, does the carbon-airbox (I think you have one, right?) use the standard MAF? Maybe that could also cause the problems.

Again, sorry, not sure what exactly it might be

Worked fine before the swap.

I have the stock plenum - no carbon airbox for me.

**jvit27** · 09-24-2007, 02:59 PM

Does anyone know an easy way to check the fuel pressure? IIRC the US motors have a schraeder valve on the front of the fuel rail. Didn't notice one on the Euro..

**JamesM3M5** · 09-24-2007, 03:39 PM

You have to put in a T fitting to check fuel pressure.

I upgraded to a Walbro GSS340, easy install. http://www.apeusa.com sells pumps and install kits (sock, wiring, foam sleeve, etc). I noticed better performance all around, since the 5bar regulator will stress the stock pump a bit, esp once it's old and starts to wear out. Mine had 150k on it when it died this past summer.

**jvit27** · 09-24-2007, 06:13 PM

Thanks James, Alex just confirmed that on the phone before I logged back in.

What's retarded is the S52 has a schraeder valve right on the front of the fuel rail and the euro doesnt even have one!

My pump has 83k on it. I'll probably replace it though since you saw an improvement.

Sigh. The rabbit hole keeps getting deeper..

**M3 Euro LTW** · 09-24-2007, 06:56 PM

I had told you Jon that someone on the list had the solution for pumps...and whallah..it appears.

james beats me to nearly everything!

I'm concerned that you mention in your post, (but I didn't hear this on the phone, or I glossed over it) that its a "bank" issue.

You've probably got a bad 02 sensor....or... some injectors in that bank are bad.

Virtually nothing else will be bank sensitive. You could move coils around as well, but if they were not working, I think you'd find rich, not lean.

Also... given 2 years on the shelf, injectors are LIKELY to be gummed up.

James, thanks for reposting that link.

Alex.

**M Dizzle** · 09-24-2007, 11:22 PM

James installed the Walbro GSS340 in my car after I was having fuel starvation at the track. Car runs great until the last drop of gas now. Dunno if my butt dyno actually noticed a performance increase.

Hope its something small and not a big issue Jon.
Oh, still waiting on those engine bay shots...and more vids.

**morerevsm3** · 09-25-2007, 08:18 AM

S50B30 uses same pump/pressure as 325i, S50B32 runs different pump and 5 bar fuel pressure, I now have 2 walbros in mine

**liquidtension** · 09-25-2007, 08:47 AM

Thought i'd pitch in, I am running stock E30 M3 fuel pumps, with the S50B32 with 5bar of FP, for more than a year with no issues whatsoever. (AFRs around 12:1 at redline), and now i am running 4psi of boost with no issues whatsoever as well..
So there you have it

**synkro** · 09-25-2007, 02:35 PM

I'm running the same pump that I had on the 325i (m50b25) and from what I know it's the same with the pump from s50b30...

**JamesM3M5** · 09-25-2007, 03:05 PM

Originally Posted by synkro

I'm running the same pump that I had on the 325i (m50b25) and from what I know it's the same with the pump from s50b30...

Yes, only the S50B32 runs at 5bar fuel pressure. Its fuel pump is specific to only the E36 M3 with S50B32 engine, hence why the pump is soooo expensive.

**jvit27** · 09-25-2007, 03:48 PM

Thanks James! Alex mentioned the pump on the phone, glad I didn't have to look far

What exactly do I need to order from them, anything besides the actual pump? (sock, wiring, foam sleeve, etc?)

**Maleckis** · 09-28-2007, 01:50 PM

All euro E36 except for S50B32 have the same fuel pump. Those fuel pumps flow 160 liters per hour. Now I have one GSS 340 in mine. It works well.

**morerevsm3** · 09-28-2007, 09:44 PM

got my 2 X GSS341 pumps and install kits from here-
http://forums.bimmerforums.com/forum...d.php?t=799621

**morerevsm3** · 09-30-2007, 03:41 AM

here is walbro with kit installed in housing for RH side of tank with standard unit alongside, note size of wire difference , LH side same except level float turned 90* as per pumpkin racing setup

**jvit27** · 09-30-2007, 12:13 PM

Thanks Alan. I tested the FP yesterday, it was just over 60psi at idle and just under 70psi when I blipped the throttle to ~3k rpm.

Within range, but a hair low.

**jvit27** · 10-14-2007, 07:01 PM

So I just upgraded the stock fuel pump to a Walbro GSS242. Not sure how it is different from the GSS340? I retained the stock sock by using a custom cnc adapter fitting..

Anyways, before the car would hesitate/stumble with a blip of the throttle and that is gone now. Driving around, the tach zings on downshifts when before it would kind of 'choke' and not be able to rev match. Low end and part throttle driving seems better too, and a run to redline also felt a bit smoother. All-in-all im very glad I did it! Thanks to Technique Tuning for selling me the last one he had in stock

Also had the injectors dynoed on the flow bench on friday, they were about as close to a perfect match as you can get. Spray patterns were consistent
Flow In cc/min @ 55psi(3.8bar)
1- 265
2- 270
3- 270
4- 270
5- 274
6- 270

Anyone wanna do the math to convert it to 73psi(5.0bar) feel free...

I'll hook up the FP gauge tommorrow and see what kind of pressure increase we got. Stay tuned

**JamesM3M5** · 10-15-2007, 09:05 AM

Originally Posted by Vitolo

So I just upgraded the stock fuel pump to a Walbro GSS242. Not sure how it is different from the GSS340? I retained the stock sock by using a custom cnc adapter fitting..

Anyways, before the car would hesitate/stumble with a blip of the throttle and that is gone now. Driving around, the tach zings on downshifts when before it would kind of 'choke' and not be able to rev match. Low end and part throttle driving seems better too, and a run to redline also felt a bit smoother. All-in-all im very glad I did it! Thanks to Technique Tuning for selling me the last one he had in stock

Also had the injectors dynoed on the flow bench on friday, they were about as close to a perfect match as you can get. Spray patterns were consistent
Flow In cc/min @ 55psi(3.8bar)
1- 265
2- 270
3- 270
4- 270
5- 274
6- 270

Anyone wanna do the math to convert it to 73psi(5.0bar) feel free...

I'll hook up the FP gauge tommorrow and see what kind of pressure increase we got. Stay tuned

http://forums.bimmerforums.com/forum...13&postcount=7

SQRT(New pressure / old pressure) * old flow rate = new flow rate

**zparker** · 11-20-2007, 01:52 AM

Question then, the s50b32 uses 24lb injectors. Is the rating at 3 bar standard fuel pressure? Has anyone actually tested the fuel pressure on the s50b32 euro m3?

What i mean to ask is; What pressure and duty cycle are injector flow ratings stated for? If they run at 5 bar then 24lb injectors will push out 31lbs. Which works out well for tuning reasons, gives you alittle bit of room for improvments etc...if they are actually 24# injectors seeing 5bar.