E30 struggles to start

[AlexSutherland]

I've had a 1991 E30 325i for a few months now and one of the issues with it is it struggles to start. I have to keep the ignition key on for 3-5 seconds before the engine fires up. What should I replace to help resolve the issue? fuel pressure components? spark plugs? Not really sure what exactly to replace in the ignition/fuel system to help the engine start more easily. Really appreciate input!

[MrBurgundy]

It could be a few different things.

If you search around this forum, you'll find a many threads with answers concerning your problem.

I'll try and point you in the right direction, though, there are many things that can cause this problem.

I'd start off by checking fuel pressure and the blue coolant temp sensor that sits in the thermostat housing.

You can search how to test that sensor with a multi meter.

[MR E30 325is]

^ Agree with Burgundy.

The search function will yield lots of things to try.

[AlexSutherland]

Thanks guys I'll try to check them out. I pretty new to forums

[Ari Ehu]

I've had a 1991 E30 325i for a few months now and one of the issues with it is it struggles to start. I have to keep the ignition key on for 3-5 seconds before the engine fires up. What should I replace to help resolve the issue? fuel pressure components? spark plugs? Not really sure what exactly to replace in the ignition/fuel system to help the engine start more easily. Really appreciate input!

Hey mate!
I had the same kind of issue, and I seem to have fixed it.
Check out my thread and see if you can find a solution on their.

https://www.r3vlimited.com/board/showthread.php?t=413874

The check valve solution worked straight away!

[AlexSutherland]

Hey mate!
I had the same kind of issue, and I seem to have fixed it.
Check out my thread and see if you can find a solution on their.

https://www.r3vlimited.com/board/showthread.php?t=413874

The check valve solution worked straight away!

Thanks mate for the advice. Are you a kiwi? I was thinking the issue with fuel system was the fuel regulator. I'm quite unfamilar with the 325i fuel system or fuel systems in general. Does the 325i have a check valve as well?

[AlexSutherland]

I recently read that the fuel check valve is built in the fuel pump for a 325i e30. Should I first test if I'm losing fuel pressure overtime while the car sits before jumping to conclusions? if it is the issue do you think it's worth replacing the fuel pump? it's about 200$ for OEM one

[e30davie]

Probably. Depends if you want to make it start instantly.

For reference my m20 starts instantly regardless of temperature or how long it's been sitting. Under 1 second of starter motor.

[Ari Ehu]

Thanks mate for the advice. Are you a kiwi? I was thinking the issue with fuel system was the fuel regulator. I'm quite unfamilar with the 325i fuel system or fuel systems in general. Does the 325i have a check valve as well?

Yeah I am how'd you guess? haha
I'm unsure about that, but I believe it does but they malfunction?

[AlexSutherland]

Yeah I am how'd you guess? haha
I'm unsure about that, but I believe it does but they malfunction?

Just curious. My father's also from New Zealand. You're right it does have a check valve but it's built into the fuel pump. From what I've read. I could be wrong but pretty sure. Changing the fuel pump is probably my best bet. Unless you think other wise. Also do you know if it's common for the gas tanks to corrode?

[Ari Ehu]

Just curious. My father's also from New Zealand. You're right it does have a check valve but it's built into the fuel pump. From what I've read. I could be wrong but pretty sure. Changing the fuel pump is probably my best bet. Unless you think other wise. Also do you know if it's common for the gas tanks to corrode?

Oh right, where in NZ is he from?
I have been told that it can be a problem, and allows the fuel in the line to flow back into the tank, instead of staying pressurised in the lines. You could do That, but a check valve may be a cheaper option, it's just a matter of trial and error. Hmm gas tanks rusting, I am unsure about that one. I do know it happens just not sure if it's common.

[AlexSutherland]

Oh right, where in NZ is he from?
I have been told that it can be a problem, and allows the fuel in the line to flow back into the tank, instead of staying pressurised in the lines. You could do That, but a check valve may be a cheaper option, it's just a matter of trial and error. Hmm gas tanks rusting, I am unsure about that one. I do know it happens just not sure if it's common.

He's lived mostly in the north shore of Auckland. How'd I just change the check valve on a 325i?

[Ari Ehu]

He's lived mostly in the north shore of Auckland. How'd I just change the check valve on a 325i?

Oh nice man, I'm from Gisborne, a check valve can be placed in on the in fuel line. But before doing so i'd recommend checking to see if pressure is held in the fuel lines first, you can check at either the engine end or by the fuel tank.

[AlexSutherland]

Oh nice man, I'm from Gisborne, a check valve can be placed in on the in fuel line. But before doing so i'd recommend checking to see if pressure is held in the fuel lines first, you can check at either the engine end or by the fuel tank.

Do I need a device to check the fuel pressure?

[Ari Ehu]

Do I need a device to check the fuel pressure?

You can use a pressure regulator but I didn't have one at the time, so if you can get a rough idea that it is holding pressure than you should see continuity, use eye protection and disconnect the battery when doing so.