Date: Sun, 18 Jul 2010 18:20:04 -0700
Reply-To: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject: Re: stalling and hard restart
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If you are 'sure' that the thing that keeps it from firing up is lack of
fuel pump running ...
you're on the right track with the fuel pump relay ..
though if your used one made the fp be on steadily ...that's sure not right.
IF ...it is simply a matter of fuel pump control...no parts like oxygen
sensor etc are involved..
Listening for the fp to pre-run is a very good habit. I do that every time
I fire up any vanagon.
there are only a few requirements to make that happen ..
power to the ecu, and ecu supplies ground to the fp relay to energize it, to
run the fuel pump.
power for the fuel pump comes from the main relay I believe ....consider
that part.
if nothing else, at least to sort through the weirdness, I'd rig a manual
fuel pump switch temporarily ..
so that you can get 12 V to the fuel pump 'for sure' .
if it's as simple as no power to the fuel pump ...that shouldn't be 'too
hard' to fix.
if it's something else...say pump runs but there's not suffecient fuel
pressure, that's anohter story of course. I like to have a fuel pressure
guage on them while sorting through stuff like this. Currently I have on
between the front seats, but running fuel through the van like that is a bit
scary ..
and the engine cover doesn't close perfectly ....and heat gets in the cabin,
but by golly, I am sure there is fuel pressure on this one van with an
intermittant igntion problem.
it would be nice to have another ecu. I have heard of one that would not
supply ground to energize the fuel pump relay, but only one. Usually they
are very good about that.
if you are sure the pre-run feature is not working ....just work on that and
it shouldn't be that hard to track down.
once past the pre-run feature, , the next time the fuel pump runs is during
starter cranking ..
and ecu knows the engine is cranking due to seeing ignition ..
like if you take another distributor and plug it into your harness, turn on
your key, and turn that distributor with your fingers, you should hear the
fuel pump run then too. That's a nice test to do ..
shows that the entire fuel pump control circuit is working. When I see
fuel pressure also during that test, then I know that whole part of the
system is working like it should.
seems to me that if the fuel pump won't pre-run, and it won't run during
cranking ...
and you are sure it's not pump or electrical connections for it ...
my mind goes to the two relays and the ecu.
I believe in redundency for the sake of not getting stuck anywhere, and so
far I have not had to arrange a back up fuel pump power supply ........but I
sure would for any excuse .
As far as I am concerend they should have two complete redundant and
indepedent fuel pump power supplies, plus manual back up.
the two relays are identical I think.
and it is amazing how many of these 20 year old relays work so reliably.
wouldn't be a waste of money to one or two high quality new ones in hand.
I wouldn't dismiss the igntion switch either, even though it is new.
I just found one the other day ..
great starter cranking ...but no igntion during cranking.
Scott
www.turbovans.com
----- Original Message -----
From: "Mark" <mbrush@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, July 18, 2010 5:54 PM
Subject: stalling and hard restart
> After new fuel tank, pump, filter, lines, ignition switch, temp II switch,
> a
> few ground wire clean ups, and an adjusted throttle switch - things are
> running MUCH better - BUT - I still have a problem. After driving for a
> bit, the bus will eventually stall and then have a really hard time
> restarting. Usually happens after I've driven it, get back in and I'm
> idling to leave a parking lot (STALLS). It's happened often enough that I
> can tell when it's NOT going to restart. The telltale sign is I don't
> hear
> the fuel pump engage for those brief seconds when I turn the key over
> (before I turn it all the way over). If I don't hear the fuel pump, when
> I
> turn it all the way over, it won't start. I keep retrying it until I hear
> the fuel pump cycle on. Once I hear that, the bus fires up. This
> happened
> with the old pump AND the new pump (though the new pump sounds a lot
> better
> when it cycles on - the old one seemed to struggle).
>
> It happened today, and I tried replacing the fuel pump relay with a spare
> I
> have. When I put that relay in, the fuel pump just cycled on continuously
> (not for the 3 or 4 seconds as normal). It didn't start. I put the old
> relay in - a few more tries - I heard the fuel pump cycle for a few secs -
> and it fired up and got me home.
>
> I know all the FI parts are interconnected, so it could be a bunch of
> things
> (O2 sensor, idle stabilizer, ECU??) - just wondering if this sounds
> familiar
> to anyone, or if anything comes to mind.
>
> Having fun learning how this machine works - but my machine is telling me
> that I have A LOT more to learn :-)
>
> Mark
>
> --
> Mark
> 1990 Westy (2.1 - manual)