Cis fuel injectors dripping?

[76pcar]

I just put new fuel injectors on my 911 with cis injection. With the fuel pump running(but car isn't). I've checked all 6 injectors and they all are dripping alittle fuel about 1 drop every 5 seconds. Should these drip at all under fuel pressure or is my fuel pressure too high.

[tirwin]

They should not drip. There are a few articles on here regarding adjusting the spray pattern. It's been a while. I think you adjust the 3mm mixture screw until the spray pattern goes from fine mist to drip and then you back it off.

Do you have a set of fuel pressure gauges? Testing the fuel pressures isn't hard and if you aren't sure whether they're in spec, it's probably a good idea.

[boyt911sc]

Check the FD's plunger and slightly push down the AFS (air flow sensor) plate downward (gently). See if will stop the dripping of the injectors. The most likely culprit for this type of problem is the "too rich" mixture setting and not allowing the plunger to close properly.

Could you start the engine with this present condition? Keep us posted.

Tony

[boyt911sc]

Originally Posted by tirwin

They should not drip. There are a few articles on here regarding adjusting the spray pattern. It's been a while. I think you adjust the 3mm mixture screw until the spray pattern goes from fine mist to drip and then you back it off.

Do you have a set of fuel pressure gauges? Testing the fuel pressures isn't hard and if you aren't sure whether they're in spec, it's probably a good idea.

Tim,

The CIS fuel injector's spray pattern is not adjustable per se. It is a pressure type (mechanically sealed) fuel injector that operates ON or OFF. Under 35 psi (+/-) they are normally closed and not injecting fuel. You could test these fuel injectors and the operating (opening) pressures (between 35 to 52 psi) are considered acceptable values.

When the plunger is at rest (engine not running) and you run the FP, there should be no drip at all. Any sign of fuel drip is not normal and should be corrected. For all six (6) injectors to have 'drips' at the same time points to FD's poor setting unless these injectors are all defective (leaking) which I doubt.

Tony

[76pcar]

Tony the fuel injectors are new so I know I'm good here. I put a 3 mm allen tool in the slot on the air flow meter and turned it about 1/3 to 1/2 of a turn counterclockwise and the dripping stopped.

So I guess the fuel air mixture is way too rich right? I also reached in and very lightly pulled down on the arm inside the air box that the sensor plate is bolted to and the dripping stopped as well. So mabe I have 2 problems?

[boyt911sc]

Is the engine running now? Keep us posted. Thanks.

Tony

[Tidybuoy]

When you say dripping...do you mean dripping or pulsing. I have a similar problem which I have not yet corrected. My plan is to test my fuel pressures this weekend and check to see if my airflow sensor is properly adjusted. I had recently removed the CIS to change gaskets, O-rings, and crush washers on the engine to eliminate oil leaks. My injector pulsing started after I put everything back together.

Here is a video of my engine with the "pulsing issue". I too have new injectors.

[76pcar]

Tony. The car will crank and run for a few seconds and then stops running.

Tony. You seem to have alot of experience here. I have another question as well.

The car will only run temporarily when I disconnect the wiring connector from the back of the air flow meter. I've heard people call this a safety switch. I think it's tied into the fuel pump

I can hear the fuel pump run with the ignition switch on when I diconnect this socket from the air flow meter.

When I reconnect this plug the car will not crank and run at all. Any ideas here?

[boyt911sc]

Originally Posted by 76pcar

Tony. The car will crank and run for a few seconds and then stops running.

Tony. You seem to have alot of experience here. I have another question as well.

The car will only run temporarily when I disconnect the wiring connector from the back of the air flow meter. I've heard people call this a safety switch. I think it's tied into the fuel pump

I can hear the fuel pump run with the ignition switch on when I diconnect this socket from the air flow meter.

When I reconnect this plug the car will not crank and run at all. Any ideas here?

Bill,

With AFS switch disconnected and ignition switch @ ON position, the FP should be running. Why do you have to disconnect the AFS connector? To test the AFS switch (IS @ ON), simply move the AFS lever up very briefly (2 sec. max.). Terminals 87a and 30 are NC (normally closed) terminals.

If the starter is not cranking the engine during start sequence, two things to check:
a). FP relay.
b). Terminal #87 is getting power.

Keep us posted.

Tony