Help injectors not squealing 1977 930

[dhg1337]

stock 1977 930, got my engine back together, had a head repaired . I have spark, both fuel pumps working fine, getting fuel at line to the fuel distributor 760 cc/30 seconds. I don't have a pressure Gauge, Checked spark plugs they are dry, no signs of fuel.

Sprayed some starter fluid into the flapper. Motor runs for a few seconds then dies. Obviously not getting fuel.

Did the test with the key on and pushed down on the Flapper (not sure why people write push up on it) of course the fuel pumps activate but the injectors don't make the so called squealing noise..

So my question is why are the injectors not squealing/pumping ? Is it possble to have good output from the fuel pump and no pressure? I searched but could not find the answer.

Thanks Danny

[JFairman]

Some people say lift up the sensor plate because thats what you do on an SC and they are not aware the 930 goes downwards.

You have to remove an injector and stick in in a clean small water bottle or something so you can see if the injector is spraying fuel.

My injectors never squeal when they open and I've never heard a CIS injector do that.. It is supposedly as the injector pintle chatters open and closed real fast.

I have heard a little short duration squeal or squeak from the fuel heads system pressure regulator as it stabilizes pressure while returning fuel to the tank.
It is only for about a half second when the pumps first come on but the noise I am referring to is not from the injectors because they are closed when my fuel pumps come on with the ignition before the starter motor is engaged.

[Jim2]

Probably lots of air in your fuel head and injector lines. You might want to break the injector line nuts loose at the injectors and hold the flapper down to run the pumps until you start to see fuel coming out of a few of the injector unions, then tighten them back up and give it a shot with the starter.

[dhg1337]

No squeal for CIS is what you are saying.

The injectors must be dry if it runs on a squirt of starter fluid.
I will check harbor freight for a fuel pressure tester. Saw something about $15

[dhg1337]

That sounds like a good idea

[JFairman]

Harbor Freight has nothing for checking system pressure and control pressure on CIS/K-jetronic injection.
You'll only waste your money and time trying the generic low quality EFI fuel pressure gauges from there.

You need one made for checking CIS like this: Star Products , TU-14PB Fuel Injection Tester - Bosch C.I.S.

Looks like it recently went up about $30 at this store... don't know if anyplace sells it for less these days.

[dhg1337]

good advice on the testor.
I know you get whatyou pay for. I was just wantIng to know the inlet pressure going into the fuel distributor.

[dhg1337]

Wow, going to have to think about the above for a while.

Messed with the car again. Could not loosen the injector at the lower connection, not moving easily. So loosen it at the disributor head. Fuel was coming out slowly no real pressure. Not sure if there should be alot in the first place.

Your right I need the real CIS pressure gauge attatchments The cheap ones don't have the right fitting.

Folllow up when I get the gauges. Only way to tell if the fuel pump is good.

[spuggy]

Originally Posted by dhg1337

both fuel pumps working fine, getting fuel at line to the fuel distributor 760 cc/30 seconds.

Danny, the factory spec for 930/51, 930/53 & 930/60 motor types is:

min 1170 cm^3 / 30 secs
(valid for both pumps together)

The single (probably original) pump on my '77 S made more than that - something sounds wrong. If that's a free-flow figure you measured, it'll only get worse working against system pressure (6.0 - 6.7 bar).

Later factory spec (e.g. 930/68) is given as 1500 cm^3 / 30 secs - for the 3.3's they also quote a required flow rate of 160-240 cm^3 / minute for the control pressure circuit (but don't mention it for the 3.0 930s).

I suspect one of your pumps may be kind of dead - that will hurt the ability of the remaining pump to push fuel through it.

Try testing individually - if you find issues and originality isn't a concern, I would suggest replacing with Bosch 044 motorsport pump(s) - widely available (including from our host), cost a fraction of some of the original pumps and out-perform them by a huge factor (I'm presently running a single pump on CIS for 370 RWHP). Only hassle is the fittings to make them bolt-in - but they're around.

As others have said, it may take some time to get fuel through to the injectors - the spec for the crack pressure is 2.1 bar, +1.1 bar, BTW.

HTH.

[dhg1337]

Kind of strange I am having this problem from sitting for 3 months. I did change the fuel filter while apart. The Arrow points up, the one I replaced did the same.

Gauges will provide the answer hopefully.

one good thing , the motor sounds good on a shot of starter fluid.

Thanks Danny

[dhg1337]

found the same spec in the manuel, i am putting out alot less.

4. Switch on ignition for 30 seconds. Both pumps
must deliver 140 liter/hour or 1170 cc in
30 seconds.
Note
If delivery rate is less than this specification,
check pressure of fuel pumps to determine which
pump is defective.

[spuggy]

Originally Posted by dhg1337

found this in the manuel, i am putting out alot less.

4. Switch on ignition for 30 seconds. Both pumps
must deliver 140 liter/hour or 1170 cc in
30 seconds.
Note
If delivery rate is less than this specification,
check pressure of fuel pumps to determine which
pump is defective.

I pointed that out a couple of posts ago.

[dhg1337]

I know. Please check on me when I get my gauges.
Thanks Danny

[dhg1337]

worked on the car a again. I tested the flow at the rear fuel pump and the fuel filter outlet. Both put out the required 1170 cc/30 seconds. Before I was checking flow at the line from the fuel filter that connects to the fuel distributor. That line has a Y in it for the return to the tank. I clamped the return line and now i have great pressure in the system. So much one of my rubber to metal lines is squirting out fuel. (need too replace that).

How can you have pressure if that line is free flowing back to the tank? What am i missing.

[dhg1337]

fuel filter and return line together labeled.

[dhg1337]

After looking at old pictures. I figuered out what he problem was, the fuel filter line got mixed up with the fuel acumulator. now runs. I think it is running lean now, but that is another problem.