E30 325i running poorly (fuel pump?)

[peter1233]

Hi,

Looking for some advice on my 325i E30, the car is from production year 1986. This is not a daily driver it's actually built and spec'd for rally driving.
I've identified that I need to start with the fuel pump and then work my way towards intake leaks etc. I've cleaned the MAF already and it didn't have any effect.

If anyone could help me identify which fuel pump I need to order, that would be much appreciated. I've attached a photo of the fuel pump top part.

Because the pumps that I've seen only have one line and the one in the car has two fuel lines.
https://imgur.com/a/K9go5F7

Little bit of a backstory to how it runs.
It starts, idle is very rough and it stalls right after start if you don't give it gas. When pressing the gas pedal the car response is lagged so if you put the pedal to the floor it takes a good one to two seconds for the car to respond and the response is not a steady incline of RPM's going up, it's more like a roller coaster. You can keep the engine running like this keeping your foot on the gas pedal, but after you release the gas pedal it studders and shuts down.

Any advice is welcome! Thanks!

[95BMWIC]

Hi,

Little bit of a backstory to how it runs.
It starts, idle is very rough and it stalls right after start if you don't give it gas. When pressing the gas pedal the car response is lagged so if you put the pedal to the floor it takes a good one to two seconds for the car to respond and the response is not a steady incline of RPM's going up, it's more like a roller coaster. You can keep the engine running like this keeping your foot on the gas pedal, but after you release the gas pedal it studders and shuts down.

Any advice is welcome! Thanks!

1988 - and on the fuel pump is mounted in the tank.

See this site for identifying part numbers: https://www.realoem.com/bmw/enUS/select (Catalog is Classic - E30)


If you "give it gas" to keep it running (although lagging) - its probably not the fuel pump. There is a simple flow test to check - pull off fuel hose from the pressure regulator and and place it into a container - run the fuel pump for 30 seconds and you should have 30oz of fuel.


Your symptoms are most likely from vacuum leaks - dirty ICV

See Post #12 - https://www.bimmerforums.com/forum/s...0-Jedi-Master)

[mbonder]

That sounds more like a vacuum leak, more air getting into the system than should be there, which is why when you give it more throttle, you are adding more fuel to the mixture, getting it back to a normal range and the car still runs. It wouldn't hurt to check fuel pressure at the regulator, or to replace the pump if it is old/original, but this may not solve your problem.

[peter1233]

Hi,

Thanks for the tips! I found some old documents and checked the VIN, it's actually a -86 production car so MY -87.

[sienayr]

Check fuel pressures before you throw a fuel pump at it. Most parts stores will rent you one for free. Also smoke test the car before throwing parts at it to make sure there are no vacuum leaks.

This guide is very helpful for systematic troubleshooting so you don't have to guess and waste money on parts you don't need. It's not e30 specific but the basic troubleshooting steps are pretty much the same.
https://hpsimotorsports.com/blogs/te...n-tech-article

[82eye]

cleaning the icv and replacing all the rubber solves a lot of stuff if it hasn't been looked at in a while.