Date: Wed, 25 Jul 2007 23:08:15 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Is ECU involved in getting power to fuel pump when turning
ignition switch on?
In-Reply-To: <00fd01c7cf2f$d6352c50$6401a8c0@TOSHIBALAP>
Content-Type: text/plain; charset="iso-8859-1"
OK!
I got the terminal # reversed. The point I was trying to make was that
full battery voltage is supplied to the coil. The side with multiple black
wires. The other side is switched by the ECU completing the path to the
chassis.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Scott Daniel - Shazam
Sent: Wednesday, July 25, 2007 10:51 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Is ECU involved in getting power to fuel pump when turning
ignition switch on?
Hi
Coil terminal 15 of course is the 'ignition on' 12volts DC , terminal of
course.
On a coil system terminal # 1 is connected to the points. ( in all this
wiring '1' is always associated with ground - points supply ground )
Whether " Terminal #1 of the coil does get battery voltage " ....
Depends on how you look at it.
I'm sure there is voltage there during the process, but I wouldn't say it
'gets battery voltage." I wouldn't say that at all.
The purpose of ballast resistors as I understand them.....
( a small embellishment to somewhat reduce one inherit weakness of points
)
is to reduce the voltage flowing in the points to help them last longer,
arc
less, etc.
during cranking to start, the resistor is bypassed so the points get the
full 12 volts , to perk things up to help the engine fire up , during
'run'
the points get power through the resistor, which reduces the voltage.
I should hope that an ECU that is directly involved with the primary
ignition circuit, as on 2.1 waterboxers and Subaru engines.....would
change
dwell with rpm, as needed.
This is an example of how extremely compromised and lame points are
compared
to electronic ignition.
It's even, I realize, very parallel to carbs/versus electronic fuel
injection.
The electronic system can be so precise, and optimized beautifully for
each
different parameter, where the mechanical system, ( carb or points ) is a
general compromise, and subject to mechanical wear, as well.
Scott
wwww.turbovans.com
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Dennis Haynes
Sent: Wednesday, July 25, 2007 8:54 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Is ECU involved in getting power to fuel pump when turning
ignition switch on?
Terminal #1 of the coil does get battery voltage. The ECU switches the
path
to the chassis in response the hall sensor. Basic ignition coil operation
even back to points. Points closed or ECU conducting, coil is charging,
magnetic field builds. Points open or ECU opens, magnetic filed collapses
and high winding side of coil generates the high voltage to create a
spark.
Back in the points day the condenser was needed to allow for the reverse
current as the field collapsed and prevent the points from arching. Dwell
was the angle how long the points were closed. Longer is better especially
at higher speeds. Minimum point gap was needed though to stop arc. Some
cars
used ballast resisters to limit current at low speed, bypassed during
starting to compensate for lower battery voltage. ECU based systems will
change dwell in response to speed.
Dennis
>From: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
>Reply-To: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
>To: vanagon@GERRY.VANAGON.COM
>Subject: Re: Is ECU involved in getting power to fuel pump when turning
> ignition switch on?
>Date: Mon, 23 Jul 2007 21:57:31 -0700
>
>See SDF below -
>
>-----Original Message-----
>From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of
>David Kao
>Sent: Monday, July 23, 2007 9:42 PM
>To: vanagon@GERRY.VANAGON.COM
>Subject: Re: Is ECU involved in getting power to fuel pump when turning
>ignition switch on?
>
>If you look at the fuel pump relay circuit you may wonder why the fuel
>pump relay gets power from the #15 terminal of the ignition coil.
>This terminal does not have +12V there. The #1 and #15 terminals are
>the two leads of the primary winding of the ignition coil. The #1 pin
>is connexted to ECU.
>
>I believe the ECU feeds the #1 terminal with the pulsation current, which
>makes the high voltage winding to generate high voltage for the spark
>plugs.
>This pulsation current then comes out of terminal #15 to feed to the fuel
>pump relay as the power source for the relay.
>
>If for any reason the engine stops (misfires permanently) wheile you are
>driving the van, the Hall sending unit will stop generating the Hall
>signal.
>The ECU will stop feeding the pulsation current as a result. Consequently
>the fuel pump relay will lose its power from the #15 terminal. As a
result
>the relay deactivates and the fuel pump stops. This is indeed a safty
>feature.
>You don't want the fuel pump continues to pump causing fuel line to
burst.
>
>As an example, if your van is rear ended by someone, which knocks out the
>ignition distributor and the engine stops. Let's say you pass out from
the
>impact from the rear. So the ighition key is still in the on position.
>The fuel pump will stop pumping gas, which may prevent a fire or an
>explosion
>as a result. Basically if the engine stops the fuel pump will not pump.
>When the engine is being cranked the fuel pump will pump because the
engine
>is turning.
>
>SDF - no, the fuel pump runs during cranking because of the 'start
signal'
>from the key. It's a black/red wire in the black junction box. After
>'start' ..when the engine is running....yes, then it gets the 'keep the
>fuel
>pump relay energized' information from the ignition system.
>I believe this to be correct.
>
>If you have a bad ignition coil the fuel pump will not pump. If you have
a
>bad
>Hall sending unit the pump will not pump either. If the ECU is bad of
>course
>the pump may not pump either. I would check the Hall sending unit first.
>Usually
>the only way it will break down is bad connection. I would check the
>ignition
>coil's primary winding. ECU is possible so it would be nice if you have a
>spare.
>
>SDF - for whatever it's worth......in thousands of vanagons I worked on,
I
>have never ONCE found a bad hall sensor. I know everybody goes checking
for
>that cause it's in the Bentley ....I never even think about it, never
find
>a
>bad one etc. I have all these parts for sale, good used, of course.
>
>Hope this makes some sense to you.
>
>David
>
>
>
>
>
>
>
>_________________________________________________________________________
__
_
>________
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