RE: IML: 81 Imperial changeover

["Dick Benjamin" <dickb@xxxxxxxxx>]

Yes, the function is exactly the same as an oil pressure sender for any car
with an idiot light for oil pressure.  The problem with using one of those
as a substitute is that the threshold pressure is way too low - the EFI
system requires a pressure threshold of 20 PSI or higher, and there are very
few oil pressure senders that have that high a threshold.  As I mentioned a
few messages back, I did find one that will substitute, from Summit Racing,
and I posted the information on that in the IML tech section - this was in
about 1996 or so, and I've forgotten the part number, but I'm sure you can
track it down at Summit.   The purpose of the switch they sell is to shut
down a race engine should the oil pressure go too low, before the engine is
destroyed.  The pressure threshold is 30PSI, which is a bit high, but I used
one of those switches in one of my EFI cars for years, and as far as I know,
the new owner is still using it.  The switch from Summit is not exactly the
same physically, but with a little careful positioning of fitting adaptors
and wire connectors, it can be made to fit in the available space.

Dick Benjamin

-----Original Message-----
From: mailing-list-owner@xxxxxxxxxxxxxxxx
[mailto:mailing-list-owner@xxxxxxxxxxxxxxxx] On Behalf Of
arbie104@xxxxxxxxxxx
Sent: Thursday, February 23, 2006 6:04 PM
To: mailing-list@xxxxxxxxxxxxxxxx
Subject: RE: IML: 81 Imperial changeover

I just realized that the FPSooks almost identical to the oil pressure sender
on my 66 Polara 383!  Does anyone know the limits of the FPS versus the oil
pressure sender?
 -------------- Original message ----------------------
From: arbie104@xxxxxxxxxxx
> Will the car start if I just unplug the FPS?  What is the FPS function?  I

> probably won't have time to try this till Saturday.  Thanks
> 
> -------------- Original message -------------- 
> From: "Dick Benjamin" <dickb@xxxxxxxxx> 
> 
> Yes, you can check the pressure that way.  The pressure there can get up
to 80 
> PSI, so be careful to have a secure connection to your gauge.
> 
> The two wire connector on the pump is the one to check. One wire is ground
(I 
> think it is black), the other one (I can't tell you the color because I am

> colorblind), is the one we care about - it varies between almost Zero to
almost 
> 12 volts, depending on the fuel demand signal put out by the computer,
which 
> knows the throttle position, the fuel flow rate, the RPM, and a bunch or
other 
> things, like temperature of the air, fuel and coolant, exhaust oxygen,
altitude 
> etc.. 
> 
> The power module basically is just a DC coupled power amplifier, which
takes the 
> computer output and boosts it up to a strong enough signal to operate the
pump 
> motor.   One of the failure modes (usually caused by someone shorting the
output 
> to ground) is a failed transistor in the final output stage.  Depending on
which 
> one failed, the power module might be putting out a solid 12 volts all the
time; 
> this would also explain your symptom.
> 
> The first thing I'd like to have you do is to pull the wire off the FPS as
soon 
> as the engine starts - to see if that reduces the fuel flow to something 
> reasonable and the idle becomes normal.  If this works, forget all the
other 
> fiddling around - you've found your problem!
> 
Dick Benjamin





-----------------  http://www.imperialclub.com  -----------------
This message was sent to you by the Imperial Mailing List. Please 
reply to mailing-list@xxxxxxxxxxxxxxxx and your response will be 
shared with everyone. Private messages (and attachments) for the
Administrators should be sent to webmaster@xxxxxxxxxxxxxxxx
To UN-SUBSCRIBE, go to http://imperialclub.com/unsubscribe.htm