CIS Injector Volume

[awjens]

I am getting ready to run my engine on a test stand. I built an engine harness cable and extended the fuel and oil lines from the car. I am going to check CIS pressures tomorrow. I ran the fuel pump and lifted the air sensor plate. I put all six injectors in plastic bottles with the injectors poked thru the cap. I let it run for a couple minutes and then shut it down. It is very difficult to measure fuel this way so I weighed it with my wife's jewelry scale. I will post a picture of the results. By weight after pumping about 1/3 of the bottle they weighed as follows.

#1 153.9 #2 159.0 #3 155.6 #4 158.9 #5 157.2 #6 154.3

So the differential from low to high is 5.1 grams. Considering the highest volume of 159.0 grams that is roughly 3% difference. I had seen posts where the volume in glass bottles was significant. Mine seem very close.

The problem is they seem to be leaking when the air sensor plate is closed. Just small drips. I realize this condition doesn't normally occur as the pump is not normally running for extended periods when the sensor plate is closed. Should these injectors drip at all in this test? The spray patterns are not all the same but the volume seems close. Maybe the fuel isn't atomizing the same so I may replace all the injectors. I planned on testing the new injectors for volume and spray pattern the same way. Is this a good test and should they drip with the plate closed. I would say a drip about every 5 seconds.. when I shut the pump down it appears the dripping stops. These tests were done with the WUR unplugged in 60 degree ambient temp.

[T77911S]

they should not drip...but....it also depends on where your mixture is set. as you richen the mixture they will start to spray. if all 6 are leaking it might be the setting, if jsut 1 or 2 are leaking then bad injectors.
volume looks ok
im not going to be that much help because this is a tough call on replacing them. for me it would depend on other things like how does it run, does it start ok, how is the idle, how is the $$.
if it was a new engine and the CIS was good and i had the $$ i might replace them, again, depends on how it runs.

just replaced all 6 on my 930. smoothed out the idle.

[grantsmells]

correct me if i'm wrong (which is very possible), but from my experience if they are dripping it's your fuel distributer leaking, not your injectors. With a good FD you should be able to have your injectors removed from the lines. and still have no drips (except for whatever fuel is already sitting in the line, which will stop dripping after a minute)

[awjens]

I purchased a CIS pressure testing kit today. Is there a link to check these pressures?

[gomezoneill]

Like the other post said your mixture screw is set to rich causing the dripping lean it out a little by unscrewing it 1/4 to 1/2 turn. Need to know year and model for more help.

[boyt911sc]

Originally Posted by grantsmells

correct me if i'm wrong (which is very possible), but from my experience if they are dripping it's your fuel distributer leaking, not your injectors. With a good FD you should be able to have your injectors removed from the lines. and still have no drips (except for whatever fuel is already sitting in the line, which will stop dripping after a minute)

Grantsmells,

A good fuel distributor should not deliver fuel when the FD plunger is at rest unless the fuel mixture is set too RICH causing premature fuel delivery. However, a defective fuel injector could leak with a good fuel distributor. Testing it with and without fuel injector installed is a more reliable way to evaluate where the problem is coming from. I completely agree with you that a properly set FD should not deliver fuel to the injector/s. After a fuel distributor rebuild, my first test is to run the FD with only fuel lines connected and no fuel injectors installed. Set the system fuel pressure and observe for any sign of leak around the body of the FD.

Tony

[awjens]

I turned the mixture adjustment 1/2 turn CCW and the dripping stopped on all six injectors. At 1/4 turn a couple still had very frequent drip.

The drips occurred with injectors in place or removed.

[gomezoneill]

That's a good starting point for initial start up.