Dripping Injector

[Rudedog]

I am having major problems starting my car after it sits for about an hour. My friend thinks I have a dripping injector or 2 in my CIS. I think he is right. Is there anyway to find out which ones are dripping? Is there a test that can be done? I do not want to by 6 new injectors at $50 dollars each. Any ideas will be welcome. Thanks

[Elu]

Warm or cold? I would suggest that it is not a dripping injector but rather some other problem with the accumulator. Maybe this bump will get someone with more experience, however, mine did the same thing, it was a bad fuel mixture and a small crack in the accumulator which caused air to enter the system. it just wouldn't hold pressure....and then there is also the possibility that it is the fuel pump check valve. Maybe even a bad or cracked fuel line...(rubber) If your injector leaks you would smell gas.

[Rudedog]

I do smell gas after I shut down the engine. I am looking for a way to test the injectors.

[2.7RACER]

This has been covered.
Briefly remove the injectors from one side, (three).
With the fuel line stilll connected place all them in a large jar or can. Have someone turn on the ignition, do not try to start. The injectors should not flow.
If the injectors are flowing, even slightly, turn off the ignition, adjust the mixture control for the fuel distributor, CCW about 1/4 turn.
Now recheck for flow.
If the injectors are not flowing now is a good time to check them for proper flow.
With the ignition on, gently lift the air flow arm. The injectors should flow immediately. Look at the pattern from each. Should be a nice strong cone shaped pattern. Look for a deformed pattern, weak flow, etc.
All should flow the same volume. This is not a matching flow test, just observing for obvious flow issues.
I had a flooding issue several years ago. My mixture screw was too rich. Did this test, backed off the mixture screw. No more problems.
I also had some extra injectors so I observed all 12 and picked out the best 6 for use.
Techron is magic for cleaning partially obstructed injectors.
You'll need to fine tune the mixture screw before you are done.
Have fun.

[ianc]

As Elu says, most CIS warm start problems are either the fuel accumulator or the fuel pump check valve. To check, hook a fuel pressure gauge up, let the system get to pressure, then shut off. There are published specs as to what the residual fuel pressure should be after a certain amount of time. If yours sinks like a stone, then you have leakage somewhere, and 9 out of 10 it is the acccumulator or check valve.

ianc

[Rudedog]

Thanks, I will try the checks you mentioned this weekend. I will let you know how it works out.

[Gunter]

The mix adjustment screw has no influence on the operating pressure; it just changes the air/fuel component ratio, not the pressure.
Aside from obvious fuel leaks in the lines, don't forget the check the CSV; it should only add fuel for a few seconds during cold-start.
Leaking CSV and injectors would give a rough idle.
Test them and let us know.

[Rudedog]

I have tested all injectors, replaced all injector holders and O rings. That was not the problem. I am going to replace the fuel accumulator next. I'll let you know if it works.

[1980 911 sc]

if you smell gas.... maybe a fuel leak? that would explain why it seems like the accumulator. Its job is to keep the fuel under pressure to prevent the fuel vaporizing next to a warm engine. If you have a leak, the accumulator cant keep the fuel line pressure up and makes it very hard to start when warm...

as for how to find a fuel leak.... do not use an open flame =P

[vash]

hey rude. sounds like you are about to start chasing the prob. if you get a CIS gauge, which is something like $50 from harbor freight, you can narrow the problem to a specific component. it is easy as hell.

if you are going to guess, then at least start with the check valve. it is cheaper. if not, toss $100 to the accumulator, if not, then some more benjamins to the WUR. basically, what i am saying is to NOT GUESS.

btw, what year car are we talking about?

[Rudedog]

Mine is a 1975. The CIS is 31 years old. I have a harbor freight close to my place. What do they call the gauge?

[vash]

i think it is called a bosch CIS pressure tester. on my 75 car, when the accumulator went bad, fuel dripped from the bottom. do you feel any wetness at the bottom of the accumulator? i think there is some type of weephole there.

[Gunter]

Rudedog: Accumulators from early 911's have only 2 lines, later on Porsche added a 3rd line to the bottom to return any possibly leaked gas back to the tank.
Some people with early cars have added the later style accumulator and just plugged the bottom nipple.

[Elu]

Haha...Gunter said "Nipple"

[Gunter]

Not the ones that cows have to suck on.
Nipple: "A short pipe threaded on both ends" according to the Dictionary.
Earlier accumulators had two, later ones had three.
Sucking not recommended.

[Elu]

lol