Yet another fuel delivery question

[piman]

I have searched the posts for a similar problem but can't find one.

90 535ia - DOP 04/90

The car is hard starting. Sometimes 6 or 8 tries. After it is going it is fine. Once shut off it could start the next key turn or two. Usually starts best first thing in the morning fine.
The pump has the BMW hiss for quite a while.
The plugs,wires,rotor,cap, etc are not even a year old. The car runs great once it starts.
I bought a new bosch pump to have on hand. Some people say it is the regulator. Where is it located?
Plan on removing old pump today and cleaning induction screen and replacing f-filter.

Just thought someone could shed some light.

Thanks in advance.

[Bill R.]

fuel rail at the engine. It has a vacum line going to it. Your problem is likely to be a back check valve at the fuel pump. There is a check valve available to go in line without replace the pump but if you already have a new pump i'd just replace it. Typical symptoms of a bad check valve are hard starting when warmed up and say you drive somewhere park for 30 minutes and then try to start, it will take some cranking then. But it will usually start fine on a cold start in the morning. This can also be a bad pressure regulator or leaking injectors. If its leaking injectors it will start quicker if you hold the gas pedal to the floor when giving problems on a hot start. This is the clear flood mode and it backs off on the fuel to the engine giving it a chance to dry the cylinders if flooded.

I have searched the posts for a similar problem but can't find one.

90 535ia - DOP 04/90

The car is hard starting. Sometimes 6 or 8 tries. After it is going it is fine. Once shut off it could start the next key turn or two. Usually starts best first thing in the morning fine.
The pump has the BMW hiss for quite a while.
The plugs,wires,rotor,cap, etc are not even a year old. The car runs great once it starts.
I bought a new bosch pump to have on hand. Some people say it is the regulator. Where is it located?
Plan on removing old pump today and cleaning induction screen and replacing f-filter.

Just thought someone could shed some light.

Thanks in advance.

[Martin in Bellevue]

Check the fuel pressure before the rail. Also swap in a new fuel filter & soft fuel lines.
I'd also check for a loose crank position sensor & maybe swap in new main & fuel pump relays in the ebox.

[piman]

old pump out new going in now. thanks guys