Rebuilt Engine Won Idle

[targa80]

Originally Posted by gomezoneill

........ Pull the injectors and use cans or jars so you can see the fuel delivery and post a video.

You can buy six plastic baby bottles and cut the tip of the nipples so the injectors will fit through. You can then test all six injectors at the same time for leaking, spray pattern and each bottle should have the same amount of gas after doing the spray test.

[targa80]

You may also may want to make set of test leads with a momentary push button so you can turn on the fuel pump by jumping the relay terminals 87a and 30 on the fuel pump relay. You will still need to turn the ignition on but the pump wont run until you hit the momentary contact. This also eliminates the need for a helper.

This is a momentary push button jumper I made over 40 years ago and I still have a need for it once is a while. Each lead is about 12 feet long.

[Swazzy]

Thank you Pat for posting these pages.

The update at this point is that I removed all injectors and placed in containers, and upon turning on the pump only, they all squirted, which they should NOT have. However if I push down on the sensor plate they stop squirting. Is there any adjustment on the mixture control unit, once the sensor plate is in the correct position, that forces the plunger to the closed position?

Additionally, the FD (and WUR) was rebuilt, but there is inconsistent resistance if I manually move the sensor plate up and down so I am assuming the plunger on the FD may not be operating correctly. I am sending that back to the shop to double check the accuracy of the rebuild. Upon confirming the plunger is good, I will continue testing and post results.

Thanks again,
Marc

[Swazzy]

Yes, I did make a switch and jumped the pump relay to perform the testing.

[proporsche]

the adjustment in through the little hole next to the fuel distributor 3mm allen wrench

[proporsche]

here

[Swazzy]

Thanks Ivan, I knew that is the mixture control but did not think that had the range to fully close the plunger. My bad. Once I get the FD plunger operation itself checked out I will do this.

[targa80]

Originally Posted by Swazzy

.....
The update at this point is that I removed all injectors and placed in containers, and upon turning on the pump only, they all squirted, which they should NOT have. However if I push down on the sensor plate they stop squirting. Is there any adjustment on the mixture control unit, once the sensor plate is in the correct position, that forces the plunger to the closed position? Ignore the Down Draft parts of the manual.

Additionally, the FD (and WUR) was rebuilt, but there is inconsistent resistance if I manually move the sensor plate up and down so I am assuming the plunger on the FD may not be operating correctly. I am sending that back to the shop to double check the accuracy of the rebuild. Upon confirming the plunger is good, I will continue testing and post results.

Thanks again,
Marc

Here are more pages from the CIS Service Manual that may help:

You can adjust the resting zero stop of the sensor plate to prevent the injectors from opening at rest. Also, with the fuel pump running and you manually lift the sensor plate you will feel the fuel pressure resistance from the Fuel Distributor plunger and hear the noise from the the injectors opening. When you let the sensor plate go it free falls to the resting position and the plunger will drop back to the resting position and the injectors will close.

I will post several more pages from the manual.

[targa80]

[Swazzy]

Thank you for the replies. One last question before the workweek:

I don't yet understand the relationship between the sensor plate, the mixture adjustment screw, and the FD plunger. If I assume the FD is working properly, only that it does not fully close at sensor plate rest (so the injectors are squirting), do i turn the mixture adjustment screw (counter clockwise for lean) substantially until the plunger closes? And then would I be able to reset the sensor plate if it had moved out of resting position with the turning of the mixture screw?

Or what is the exact process to make the plunger close at sensor plate rest?

Marc

[targa80]

Originally Posted by Swazzy

Thank you for the replies. One last question before the workweek:

I don't yet understand the relationship between the sensor plate, the mixture adjustment screw, and the FD plunger. If I assume the FD is working properly, only that it does not fully close at sensor plate rest (so the injectors are squirting), do i turn the mixture adjustment screw (counter clockwise for lean) substantially until the plunger closes? And then would I be able to reset the sensor plate if it had moved out of resting position with the turning of the mixture screw?

Or what is the exact process to make the plunger close at sensor plate rest?

Marc

Maybe the attached image will help:

As you can see if the sensor plate is aligned with the bottom of the "V" and you have the injectors turning on it means that the Control plunger is sitting too high in the Fuel Distributor at rest and provides enough fuel pressure via the "A" ports to turn the injectors on. If you turn the idle mixture adjustment with the 3mm allen key CCW the plunger will be lowered reducing the fuel pressure flowing via ports "A" and shutting off the injectors. I would turn the idle mixture no more than one turn at a time and test using six baby bottles to captue the fuel. Once this adjustment is done and the injectors stay closed with the pump running then you will be able to test the system fuel pressure, cold control pressure and residual pressure. Their really is no shortcut to testing and verifying each step. once the car is running you will need to fine tune the idle mixture adjustment screw and the idle air bypass screw (Big round screw on the left back side of throttle body) to set the idle RPM's and the idle mixture. I do not have a gas tester so I use a automotive digital multimeter set to the 4 cylinder dwell setting to do the fine tuning of the idle mixture.





The following images are from a thread I posted on testing the CIS in 2014 to verify that the new injectors were working and they all delivered the same amount of fuel. Ya gotta love those baby bottles.

[targa80]

I just remembered that your car is a 79 and that it did not come with the Lambda control box and associated hardware. One less thing to test.

[Swazzy]

Thanks Pat, I got it now. Really appreciate your patience and help.

[boyt911sc]

Originally Posted by Swazzy

Thank you for the replies. One last question before the workweek:

I don't yet understand the relationship between the sensor plate, the mixture adjustment screw, and the FD plunger. If I assume the FD is working properly, only that it does not fully close at sensor plate rest (so the injectors are squirting), do i turn the mixture adjustment screw (counter clockwise for lean) substantially until the plunger closes? And then would I be able to reset the sensor plate if it had moved out of resting position with the turning of the mixture screw?

Or what is the exact process to make the plunger close at sensor plate rest?

Marc

Marc,

Assuming that there is no problem with the fuel distributor, adjusting the fuel mixture would have no effect on the sensor plate position. Whether you turned the screw CW or CCW would have no adverse effect to the sensor plate alignment unless the control plunger is not freely moving up or down.

Test run the FP and turn the mixture screw CCW until you are able to stop the fuel flow from the 6 fuel injectors. Then make small CW adjustments to get the fuel to flow. Stop and make a final adjustment (1/2 CCW).

You should be able now to measure your fuel pressures without dumping raw fuel to the combustion chambers. Keep us posted.

Tony

[Swazzy]

Gentlemen,

Progress!! - 1.5 CCW rotations (in quarter turn increments) of the mixture adjustment screw engaged the FD plunger and cut off fuel to the injectors.

The system pressure looks OK at 75 psi, the control pressure is about 15 psi (it's a 45 WUR, and it's 65 degrees F out) however the residual pressure drops to zero in 10 seconds.

I disconnected the bottom of the FA (the tank return line), pump off, and fuel poured out. Correct me if I am wrong, but doesn't that mean there is a bad diaphragm in the FA?

It's that, or the pump check valve that causes this kind of immediate residual pressure drop yes?

Thank you!

[proporsche]

yup, start with clamping the return line to the tank...could be the check valve or the fuel accumulator(the big green thing on left side)..;-)

good progress ,thou

Ivan

[targa80]

The link below was posted by boyt911sc on testing the fuel accumulator back in 2009.

Fuel Accumulator Test.... Show & Tell.....

[boyt911sc]

Originally Posted by Swazzy

Gentlemen,

Progress!! - 1.5 CCW rotations (in quarter turn increments) of the mixture adjustment screw engaged the FD plunger and cut off fuel to the injectors.

The system pressure looks OK at 75 psi, the control pressure is about 15 psi (it's a 45 WUR, and it's 65 degrees F out) however the residual pressure drops to zero in 10 seconds.

I disconnected the bottom of the FA (the tank return line), pump off, and fuel poured out. Correct me if I am wrong, but doesn't that mean there is a bad diaphragm in the FA?

It's that, or the pump check valve that causes this kind of immediate residual pressure drop yes?

Thank you!

Marc,

Do a residual fuel pressure test to the following:

• Fuel pump check valve.
• Fuel accumulator.
• System pressure.

First test the FP check valve by installing a pressure gauge between the FP and FA. The shut off valve should be located before the fuel accumulator. If the FP check valve passed the test, move to the next test.

This time, place the pressure gauge after the fuel accumulator. Or a simple test is to remove the bottom port (drain) of the FA and test run the FP for a couple of seconds (max.). Place a suitable container under the FA with the disconnect drain line to catch any fuel that might come out.

Once the FP starts to run, quickly shut if off. Do not run the FP more than 3 seconds. If the fuel accumulator is good, there should be no drip coming from the bottom of the FA. If the FA is defective, you would see the fuel coming out.

The last test is too see if the primary pressure valve located inside the FD is not defective. The gauge is connected the conventional way (gauge installed between FD and WUR). Keep us posted. Thanks.

Tony

[Swazzy]

Update - After fuel pressure diagnosis, I discovered a leaky FA. New one installed today.

Now Fuel Pressure tests are solid. Residual pressure stronger then spec. Slight exception on Control Pressure which may be little low at 15 psi?

Cleaned all the plugs and car started up strong, many times starting and restarting no problem as I dialed it all in.. Able to set timing, mixture and idle.

Thank you all very much for your guidance!

-Marc

[proporsche]

congrats Marc....;-)

Ivan