Fuel pump issue

[slo325i]

Hey guys,

I'm having a little issue with my fuel pump here. It starts and drives fine but this has been always bothering me. My fuel pump doesn't prime when I turn the key on (just before starting the car). I thought I was supposed to hear it buzzing or at least some kind of a hum but I get nothing. When I crank the car it takes a quite a few cranks before the car turns over. Maybe some kind of wiring issue? popped fuse? Thanks in advance guys.

[jlevie]

The things that would prevent the pump from running to prime (a very brief run when the key is turned to ignition on) would also prevent the pump from running when the engine is cranked over.

I'm not sure which E30's prime the pump. I do know that my 87 (with either a 152 or 173 DME) doesn't prime the pump. But if the pump (or pumps on early E30's), FPR, and relay are in good condition fuel pressure should reach normal value in about one turn of the engine. If that's not happening some parts replacement is needed.

[slo325i]

It's '89 325i. I replaced the fuel pump about a month ago. It pump is fine but the problem that I found is that the car takes a bit longer for a it to turn over now. My other car (nissan) starts like a 600cc honda cbr. It turns over in like less than a second. But this car take at least 4 to 5 revolutions before it fires. I always thought the problem was that the pump wasn't priming before cranking

[jlevie]

The first thing to find out is what the fuel pressure does as you crank the engine. That's done by tee'ing in a pressure gage at the inlet of the fuel rail. If the pressure immediately goes to 3bar, the fuel system isn't the cause of the slow to fire condition.

[slo325i]

The first thing to find out is what the fuel pressure does as you crank the engine. That's done by tee'ing in a pressure gage at the inlet of the fuel rail. If the pressure immediately goes to 3bar, the fuel system isn't the cause of the slow to fire condition.

Thank you for that advice. Now what if the pressure doesn't go exactly get up to 3bar?

[transatlantic0207]

its old but did you ever figure out your problem? what was it?
mine just started doing this same exact thing