[urq] Fuel system diagnostiocs , part 2

[qshipq at aol.com]

 IME with fuel ck valves on CIS cars, when they fail, you won't have any residual pressure only a few minutes after you shut the car off.  This sounds like (a) leaky injector(s) to me.  Also might be worth tracing the feed line to make sure there are no rust thru spots.  CIS cars fuel lines are notorious for rusting thru at the line to body mounts.

HTH and my .02

Scott J


 


 

-----Original Message-----
From: Patrick Carlier <p.carlier at pandora.be>
To: Urq at audifans.com
Sent: Wed, Sep 30, 2009 12:00 pm
Subject: [urq] Fuel system diagnostiocs , part 2










Now that I have the elctrical isuues sorted out , the nex step is to 
measure various pressures . 

To do this , a so called cis gauge set is needed . 
Often sold at more then 150$ .
I've build mine for 10€ /15$ and some spare parts . 
It takes a small valve , a pressure gauge of at least 6 bar . 
8 or 10 bar won't hurt . 
And some plumbing to put it all together . 
Anyone wan't to see it , drop me a mail and I'll send you a few pictures . 

The system presure should be 5.50 to 6.50 bar . 
This is measured by closing the valve on the gauge set , wich eliminates 
the warm up regulator . 
I've got 5.80 Bar , should be allright . 
System pressure is detremined by a reducer on the cis head itself . 
Close to the feed line from the pump . 

Next is the regulated pressure . 
For this test , the engine must run . 
Open the
 valve , start the engine and monitor pressure . 
At first with a cold engine pressure is low . 
A bit more then 1 bar at ambient temperature . 
With the  engine running , in a few minutes it should rise 
to about 3,50 Bar . 3,75Bar being the maximum . 
Mine checks out pretty good . All within spec . 

Finally the engine is shut down , and residual pressure can be measured . 
Should be 3,00Bar , and should hold to at least 2,60 after 20 minutes . 
I guess I have a little problem here . 
Altough the pressure holds to 2,40 for 20 minutes , after an hour it is all
gone .  So I must have either a leaky check valve or one or more injectors . 

I'll probably wait to look at the check valves until I can do the injector leak 
test . 

Pat 












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