E30 starting issue

[2slowE30]

Alright noob here, I’ll take any help I can get. 86 325e, won’t start unless I’m giving it gas and try a few times. If I turn the key on and off auxiliary mode maybe 5 times quickly before starting it does help, sometimes even fires right up.
Replaced the fuel pressure regulator. No help.
Do I splurge on a fuel pump next or try the relay? Any other tests or ideas before I throw money at it?

[Kershaw]

As you probably correctly assumed, you're probably losing fuel pressure at the fuel rail. Instead of turning they key to aux and off several times, how about leaving it in aux for 10 seconds. Does that change anything? The reason is that the fuel pump should be running and recharging fuel pressure. There are several reasons why you could be losing pressure:

1. faulty/leaking FPR
2. leaking injectors
3. fuel line is leaking
4. fuel tank is leaking

I would check those in that order. For the injectors, reassemble the rail out of the head and then turn the key to aux, see if any leak.

[2slowE30]

Turning it in on for 10 secs and waiting actually had about the same effect as the on/off method.
It also has kind of a rough idle at stops but never an issue when driving.
My other e30 runs like a top. This one sounds more like a tractor :/
I think some tlc is in order.

[my1stE30]

fyi ... on an E30 the fuel pump will NOT run until the engine is rotating ... sojust turning the key on will NOT recharge any fuel pressure in the rail (an old chevy vortec engine works totally different)

on an E30 when the starter rotates the engine then the crankshaft position sensor signals the ECU/DME to engage the fuel pump and the spark to the plugs

[2slowE30]

That’s good to know! Thanks!!

- - - Updated - - -

I think we have conflicting statements here.
Is the fuel pump running when the car is in auxiliary mode or does the engine need to be on?
Kershaw said leaving the key on will run the pump.

[e30oe21]

fyi ... on an E30 the fuel pump will NOT run until the engine is rotating ... sojust turning the key on will NOT recharge any fuel pressure in the rail (an old chevy vortec engine works totally different)

on an E30 when the starter rotates the engine then the crankshaft position sensor signals the ECU/DME to engage the fuel pump and the spark to the plugs

^^ not true on my 91 318iS. It primes before the engine is rotating. Since I don't own an e car to test, that may be true.

You can run the pump with a jumper before you try to start it to see if that helps.

[82eye]

yah the pump primes for a few seconds before starting. however it won't run after prime if the engine doesn't rotate.

[323i E30]

The rough idle / tractor thing makes me think that you have a vacuum leak somewhere btw.
Best check if you have unmetered air entering the engine and throwing off your air/fuel mixture.
That big elbow hose between the AFM and throttle body is often a weak spot, so I'd start by checking that thing for cracks.
It probably won't fix your starting issue, but it might help a bit.

[2slowE30]

Doesn’t look too old and didn’t see any cracks in it. But good starting place!

[Gloenser]

My cousins car had this problem, his would also idle rough when cold, it might be your cold start valve