CIS Pressure Tester………
 

Andy,

Try to get a SG Tool #33800 model. It is simple and reliable. You don’t need that fancy tool with too many accessories.

Tony

Hi all, it's been a busy week. But I did have a no-start today and my inductive timing light showed that yes there was spark.

I think we all figured that that was the case but now it's confirmed.

Hopefully I'll have more time this weekend to test.

Andy

Fuel Pressure Data……….
 

Did you get the new pressure gauge tester? It is about time to test your FP. Do you know how to test run the FP? Try to read DKLever48’s thread about the FP relay socket terminals tests.

Tony

Hi Tony, yes, I did get the Amazon gauge. I didn't get the SG gauge as I had already ordered the Amazon one before you suggested it. It arrived before I left for work the next morning.

The one I received should work, right?

[edit] The more I think about it, I think I really have to do all the tests during the intermittent no-start events, right?

Regarding the FP relay, a few months ago I expanded the feet of the existing FP relay and there was no change. I swapped in a black one, no change, and then expanded its feet, no change. Bought a new red one, no change, and then expanded its feet, no change. And then tried a jumper, no change, and nothing seemed to make much difference. Is that what you are referring to?

Thinking about it now, as it's an intermittent no-start problem, I guess could drive around with them all including the jumper and swap them in during a no-start to see if they make any difference?

If I'm remembering correctly, the tests I've actually done during a no-start are: power to the FP (yes), spark via inductive timing light (yes), lift arm in airbox to inject fuel (yes), and pulled the connection to the safety switch (yes, does run FP during no-start with switch in "ON"), and start with starter fluid (yes).

As the fuel pump is getting power during the no-starts, and during no-starts when I lift the arm in the airbox the engine does get fuel and does then start up, so I think that indicates that the FP itself is working as it should?

If that's not conclusive, I suppose I could take the cover off the FP and drive the car around and when I get a no-start give the pump a whack with a hammer to see if that helps? [edit] however, it always starts after a no-start by lifting the AFS arm or using starter fluid, so it can't be the fuel pump, right?

Andy

OK, thanks Tony, I found what I believe is the DKLever48 thread you referred to.

Is the below what you suggest I do?

I should do them with the safety switch plugged back in?

Also, as this is an intermittent no-start problem, I should do these tests 1-4 during a no-start event, right?

For the 85 & 30 "ground contact" tests, do you mean check for continuity between 85 and the car body, and also between 30 and the car body?

For test #3, do I put the relay just partially in, so I can access the prongs with my voltmeter?

Test #4 I've been doing every day for months, by lifting the AFS during no-start events to prime the engine, right?

Thanks,

Andy

Well, I had another no-start event, so I whipped out my voltmeter.

What I did not do is reconnect the disconnected AFS/safety switch, as the engine was way too hot for me to reach behind the engine and blindly fumble around.

Hopefully the engine will cool off sufficiently later today, and then I'll reconnect the switch, hope for a no-start event, and do the tests again.

But I believe disconnecting the the safety switch simply energizes 87a? Which is bridged with 86, so energizes 86? And 87a energizes 30 through the relay? So, those can be accounted for in my results below?

Also, I don't for sure how to test for "ground contact." My results show which ports (87a, 30, etc.) had continuity from each port to the car's chassis. I hope that's the correct testing method, please correct me if I'm wrong.

Lastly, I did test #3 with the FP relay not pushed in completely such that I could get a probe on each of the legs, please correct me if that's the wrong method.

Anyway, here are my results of Tony's test with the safety switch disconnected during a no-start:

1). Pull out the FP relay and do the test (ignition switch @ OFF position) for the individual terminal at the socket: A simple 12-volt self-powered test light will work well for this test or a regular non-powered test light, or a volt meter.

87...........no power no power
87a.........no power has power
86...........no power (87a 86 are bridged) has power
85...........no power (should be grounded at this point) no power, no continuity
30...........no power (has ground contact?) no power, has continuity

2). Turn ignition switch @ ON position (not start):

87............no power no power
87a..........has power has power
86...........has power has power
85...........no power, presence of ground contact no power, no continuity
30...........no power, presence of ground contact no power, has continuity

3). Next, insert the FP relay into the socket and turn the ignition SW @ ON position (not start):

87...........no power no power
87a.........has power has power
86...........has power has power
85...........should have ground contact has power, no continuity[Question, should 85 have power in this test?]
30...........no power but exhibit ground contact has power, no continuity

4). To test terminals #30 and #85, follow test #3 and do the following:
a). Remove the air filter cover and filter.
b). Lift the AFS (air flow sensor) very briefly (no more than a few seconds) Three (3) seconds are too long for this test. The FP should run and deliver fuel to the injectors.
I believe I do this test several times in an average day when the no-start events occur, the car starts when I do this process

All the above is for a NORMAL operating FP and relay circuitry. Any deviation for these conditions will identify the culprit/s. The FP is good and out of the equation. If you have any question/s, just ask. Keep us posted.

Tony

Flawed Test……..
 

Andy,

Test #1:

You are not following the instruction as indicated. The AFS switch must be connected. Second, with ignition switch OFF there should be no power to terminals #87A & #86. If you are getting power at these terminals with the ign. sw OFF, something is wrong with the ignition switch.

Double check and confirm your test results. Particularly terminals #30 & #85. Hopefully the discrepancies in your test results would make you curious and look deeper into the problem/s.

Do not be discouraged. You are just overwhelmed and over thinking this simple test procedure. If you have some question about the test, simply ask. You will be OK.

Tony

Thanks Tony, the engine is cooled down now so I just reconnected the AFS switch.

I'll do some errands now and hopefully get a no-start condition so I can test.

Here are a couple questions:

Do I need to test terminals 85 & 30 for ground contact? If so, how do I do that?

Should 85 have power in test #3?

Andy

Andy,

The AFS plug is nothing but 2 brown wires use to ground terminal #85. As long as #85 is grounded, the FP will not run unless the FP relay is stuck @ closed position (defective relay). Another source for ground to #85 is the rev limiter (see your wiring diagram).

Terminal #30 is the power source for the FP and the motor is grounded from the (-) terminal. Your FP has two (2) terminals, the (+) is connected to #30 and the (-) is grounded to the chassis.

Terminal #30 (power source for the FP) gets power either from 87A or 87. Terminals #87A-#30 is NC (normally closed) and terminals #87-#30 is NO (normally open). The coil switches the position from NC to NO and vice versa. The 2 terminals for the coil is #86 (power source) and #85 (ground). Are you still there?

Tony

Thanks Tony, oh I'm still here and that helps a lot.

Results during no-start condition with AFS plugged in

Short version, it looks like the relay is not the problem.

1). Pull out the FP relay and do the test (ignition switch @ OFF position) for the individual terminal at the socket: A simple 12-volt self-powered test light will work well for this test or a regular non-powered test light, or a volt meter.

87...........no power no power
87a.........no power no power
86...........no power (87a 86 are bridged) no power
85...........no power (should be grounded at this point) no power
30...........no power (has ground contact?) no power

2). Turn ignition switch @ ON position (not start):

87............no power no power
87a..........has power has power
86...........has power has power
85...........no power, presence of ground contact no power
30...........no power, presence of ground contact no power

3). Next, insert the FP relay into the socket and turn the ignition SW @ ON position (not start):

87...........no power no power
87a.........has power has power
86...........has power has power
85...........should have ground contact has a little power, 0.6V
30...........no power but exhibit ground contact no power

Here's some more info, fwiw.

When I got home a couple hours ago from doing errands, I shut the car off, waited a minute or so, and then tried to start the car and it started immediately.

I turned it of, and then an hour or so later I tried starting the car again and it no-started. And that's when I did the most recent FP relay test that's right above this post.

So, CSV? TTS? WUR?

Andy

I think I should probably keep an up to date list of the tests done during no-start:

1) power to the FP (yes),
2) spark - via inductive timing light (yes),
3) lift arm in airbox to inject fuel (yes),
4) pulled the connection to the AFS safety switch (yes, FP does run when key in "ON.")
5) start with starter fluid (yes).
6) Fuel Pump relay test (yes, works as it should)

Start Up……….
 

Andy,

When you start your car successfully, do you touch the gas pedal? For carb motors, you need to pump the gas pedal a few times. But never to a fuel injection system specially a CIS.

Tony

Great question. During no-start events when I have to lift the airbox arm I (feel like I) need to stomp the gas pedal every time, during and after cranking, to get the engine started.

During a no-start I lift the airbox arm for a couple seconds and then I always need to crank it exactly 2 times, for about 5 seconds each time, before it starts. And almost always I (feel like I) need to stomp the gas during the 2nd cranking.

Even when it starts normally (not a no-start) w/o me having to lift the airbox arm, which I would say is around 4 starts out of every 5, it often feels like I need to stomp the gas pedal.

After the difficult starts it often is barely running, requiring me to stomp the gas to keep it from stalling.

The need to stomp the gas pedal always goes away after, say, 10 to 60 seconds or so of driving.

And sometimes there are small, embarrassing, backfires after the difficult starts.

Andy

Andy,

I knew something strange is going on with your attempt to start the motor. My engine test stand is not attached to a gas pedal and I just turned the ignition switch. For my cars, I simply reach over the driver side windows to turn the ignition switch.

If you can not make the motor to start and run unassisted from the gas pedal, something is very wrong with your CIS. Start checking your CSV, fuel pressures, unmetered air, ignition, etc. The culprit/s is right in front of your nose but you just don’t know it.

Overcome the urge to press the gas pedal. Leave that to carbs. We are dealing with a fuel injection system. Without knowing your fuel pressures (CCP, WCP, SP & RP), you have too many unknown variables. Maybe they are good but you don’t that as a fact. You are hoping they are good and you can not rely on luck all the time. Test and verify.

Tony

During the no-start events, which occur, I'd say, about 1 out every 5 starts, I cannot start the car without using the gas pedal (after lifting the AFS arm).

Most/all of the other 4 out of 5 starts, I can just use the key.

Andy

Presently reading all I can find on the CSV and TTS...

My understanding is that the TTS grounds the CSV for a few seconds during cold start allowing the CSV to pump extra fuel into the throttle body to help with cold starting. Also that the switch is NC to initially supply the ground, and then opens after it heats up so as it no longer provides the ground to the CSV.

I just pulled my TTS and it had [edit] continuity between the big terminal and the threads, but no continuity with the little terminal. The TTS is at room temps, low 70's.

Andy

Hi all, just looking for some confirmation that my TTS test was done correctly.

[edit] This morning I touched one MM lead to the big terminal (W)of the cold (67F) VDO TTS and the other to the threaded area of the TTS body, and there was no beep. Then I repeated the same test using the small terminal (G), and there was a beep.

Then, same test between the two terminals, and no beep.

[Edit] The resistance between terminal W and the threads was around 45, between terminal G and the threads was >20M, and between the two terminals >20M as well.

Is that the entire test? Is the no continuity between the two terminals showing a bad TTS?

I know it sounds super simple, but I know me. And I know that I can miss perfectly simple and obvious things that are right in front of my eyes...

Andy

Look here, Tony already described the test entirely:
https://forums.pelicanparts.com/porsche-911-technical-forum/594010-thermo-time-switch-1978-sc-3-0-a-2.html

The 3rd page of that thread I mentioned that newer versions of the TTS are fully electronic, there's no bimetall strip and contacts inside, its all electronic. Therefore a accidential shortcut or wrong connection may damage it. Basically because of the all electronic interior they expected to last even longer and more reliable as the old electromechanic version did...

Thomas