RE: Fuel Pressure Problem?

["David Morales" <davidm@xxxxxxxxx>]

When you measured the fuel pressure, did you disconnect the vaccuum line
that goes to the regulator? In my '85 318i, the differential between
connected and disconnected vaccuum line is about 8 psi, and with it
disconnected, the pressure is normal. My 318i has the same problem of not
starting immediately. I've noticed that a couple of the injectors have a
small leak at the pintle, which accounts for a slow loss in pressure and
flooding of the manifold. I've tried cleaning the injectors with an
intensive Techron treatment, with little change. I've sort of given up, as
the only real problem is the need to crank the engine for a few seconds
before it fires. Short of changing the injectors, I'd be willing to try any
suggestion, though.

David Morales
Nashville, TN
'85 318i
'85 535i

> -----Original Message-----
>
> Date: Sat, 6 Jan 2001 17:42:55 -1000
> From: "Gregory Ott" <ottg001@domain.elided>
> Subject: Fuel Pressure Problem?
>
> Hello all.  I am about to drop some money for a new fuel pump
> for my 89 325i
> and I wanted to bounce my diagnosis off you all before I did.
> Initially, car was difficult to start occasionally.  It
> seemed at first like
> it was only after it sat for some time (1 hour or more), but
> it was not
> consistent.  If I cranked the car over for about 5 seconds a couple of
> times, it would eventually fire up.  I thought it may be a
> fuel problem.  I
> checked the fuel pressure both at the fuel rail, the pump
> with the engine
> off and the pump running and it was OK.  Initially, the
> pressure did not
> hold at the rail when I secured the pump, but I found a small
> leak in my
> test rig and I thought it was causing the loss.  When I
> checked it again, it
> held.  With the engine running, the fuel pressure was 35psi,
> about 8 psi
> low.( I could get it to go up if I pinched off the return
> line) Although I
> did not think this was causing the starting problem, I replaced the
> regulator.  Did not fix the problem.  I have concluded that
> the check valve
> in the fuel pump is probably intermittently sticking open and
> the loss of
> hold pressure I first saw was due to it.  What do you all
> think?  Thanks in
> advance.
>
> Gregg (ottg001@domain.elided)
> 89 325i
> 99 323ic
>
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>
> End of bmw-digest V9 #1689
> **************************

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