308 GTSi blown fuse and warm starting problems connected ??

Discussion in 'Technical Q&A' started by Andythebath, Aug 2, 2020 at 8:05 AM.

  1. Andythebath

    Andythebath Rookie

    Dec 29, 2019
    Problems with warm starting on a 308 led me to upgrade the fuse panels to a Classic Retrofit blade fuse type panel which I highly recommend (windows seem to go up and down a bit faster and lights a bit brighter) it didn’t however cure the warm starting problem that nearly flattens the battery each time and can be quite embarrassing at the petrol station when you turn off for 5 minutes just for fuel !!

    But today I blew the fuse for the fuel injection pump, partly my mistake as I didn’t replace the fuse that came with the new panel for the correct rating fuse, it was supplied with 7.5A and should be 15 (old fuses 16A)

    Anyway although all running fine yesterday WITH the 7.5A fuse but still with the problem of it not starting unless the car has cooled down for a couple of hours, today I go to move the car and about 5 minutes after starting the fuse for the fuel pump blows, I find it should have been the 15A not the 7.5A fuse supplied with the new fuse panel so I replaced it, tried to start again and it blew the new 15A fuse straight away !!!

    I replaced the 15A fuse with another and now seems to start and run ok but I turned it off pretty soon after testing and haven’t run it since.

    My question is that is there a link between previous hot staring problems and possible failure of the fuel pump ? Would that cause the fuse to blow?
    Any feedback much appreciated
  2. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
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    Steve Magnusson
    #2 Steve Magnusson, Aug 2, 2020 at 8:48 AM
    Last edited: Aug 2, 2020 at 8:55 AM
    Don't see how those two problems would be related, but it is important to not use a "fast blow" fuse for the fuel pump as the start-up current is quite high for a brief time, and on later models using the exact same fuel pump, they moved up to a 20A fuse (so using a 15A to substitute for a 16A is a bit in the wrong direction).

    For the hot restart issue, you need to confirm/deny the residual fuel pressure at engine shutoff (it shouldn't quickly drop to zero). What version 308i? On the euro version, an Accumulator failure will obviously leak fuel out the vent nipple at the rear, but, on a US version, such a leak is hidden by the return fuel line going from the vent nipple to the fuel tank. That's the only one of the three possible failure causes that can be checked without using the CIS pressure gauge.
    waymar likes this.

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