Re: [DML] Fuel system questions

[Jake Kamphoefner <jakekamp@xxxxxxx>]

The workshop manual (available from all the vendors) already explains each piece.  Start there first.  You don't need an idle adjustment because a correctly functioning system adjusts it for you.

A fuel system pressure tester will tell you the condition of a lot of the components, but when you've been dealing with DeLoreans a long time, you can often diagnose a problem just by the symptoms.  Once it works, it generally works; I haven't replaced a single fuel system component in the last 70,000 miles (other than changing the filter once, preventively).

Jake Kamphoefner
1063





________________________________
From: Michael Conrad <mike@xxxxxxxxxxx>
To: dmcnews@xxxxxxxxxxxxxxx
Sent: Wednesday, September 9, 2009 10:13:27 AM
Subject: [DML] Fuel system questions

  

Hello all.

I've been having some trouble with engine revving while idle, which I
understand is somewhat common.  On advice of some club members, I tried a
different CPR, and it seemed to improve my problems, so I ordered a
rebuild from Hervey and it also worked, but I do still have occasional
revving.  I can't really seem to establish a pattern.  Sometimes it drives
perfect, other times it revs with a 700rpm amplitude (from about 500 to
1200) and loses power when accelerating.  Once I even had a cloud of smoke
coming out the exhaust.  But again, other times it runs perfectly fine.
Sometimes even on the same day.  The problem most often happens when the
car is first started, but sometimes it doesn't happen until I've been
driving for a half hour or so, and once in a great while it will still
happen after hours of driving.  The intermittency is making it really hard
to diagnose.

Rather than the usual "whats my problem" email, does anyone have a nice
write-up of how the fuel system works?  And not just how it works, but why
it was designed the way it was and which components are supposed to solve
which problems?  I'd also like to hack around on it some day, so I figure
I might as well learn to understand it inside-out.

Example fun hack #1: wouldn't it be cool if you had a little servo on your
idle adjustment screw that would raise and lower the idle based on
conditions?  For example, when you're stopped on a hill it would be nice
the car was idling at maybe 1500 so that you didn't need to use gas and
brake and clutch all at the same time.  You could determine this with an
accelerometer and a speed and rpm measurement.

Example fun hack #2: wouldn't it be cool if taking your foot off the gas
while shifting caused the engine to drop rpm to exactly the rpm needed to
drive the next gear ratio?  I know this can be done with manual skill, but
it would get rid of those annoying lurches when you're changing lanes and
don't have time to look at your tach.

Example fun hack #3: put a sensor on every sense-able thing you can
possibly think of, and get real-time monitoring and logging of the
engine.  It would make future diagnosis a snap.

Thanks in advance.
Mike Conrad
vin 5732

   

[Non-text portions of this message have been removed]



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