Starting problems
Moderator: martauto
I have a 1991 325is and when I go to turn it on almost every time now, it fires up and then rpm comes back down and dies. So when I try again it'll do the same thing, sometimes I have to Rev up a tiny bit and then it's fine and sometimes on the second try it'll idle up and down and eventually it'll calm down. Any ideas on how to get rid of that? I'm getting some new spark plugs today see if itll do thw trick, anyone recommend a certain brand? Thanks!!
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Brianmoooore
- E30 Zone Team Member
- Posts: 49358
- Joined: Mon Jan 10, 2005 11:00 pm
There's a strong possibility you have a failing fuel pump.
It starts pumping initially, but then, as the available voltage falls, as a result of the starter motor's large current , the pump stalls. The engine fires up on the pressure in the fuel rail, but then dies when this fuel is used up. The second time you try, the fuel pump has a much easier time, pumping against no pressure in the fuel rail, and keeps running long enough to get the full battery voltage back again after the starter is released.
Connecting up a cheap £10 ebay fuel pressure gauge is the best way to check, but you may be able to get some info. by disconnecting the plug from the fuel pump, and connecting up a spare 12 volt battery or power supply directly to the pump, so that it isn't subjected to the low cranking voltage.
It starts pumping initially, but then, as the available voltage falls, as a result of the starter motor's large current , the pump stalls. The engine fires up on the pressure in the fuel rail, but then dies when this fuel is used up. The second time you try, the fuel pump has a much easier time, pumping against no pressure in the fuel rail, and keeps running long enough to get the full battery voltage back again after the starter is released.
Connecting up a cheap £10 ebay fuel pressure gauge is the best way to check, but you may be able to get some info. by disconnecting the plug from the fuel pump, and connecting up a spare 12 volt battery or power supply directly to the pump, so that it isn't subjected to the low cranking voltage.