Intermittent Hesitation, WUR has been adjusted!

[cab83_750]

Well, I am almost ready to pull hair. So please help.

A few months ago, the '83SC started to hesitate at 'quick' acceleration. It was intermittent and would go away for weeks. Finally, the hesitation became constant. The only way it would accelerate is if you press the gas very slowly. It also became so bad that the car would take over 5 minutes to start in the morning.

I finally bought a gauge and found out that that my cold pressure was high. So, I 'whacked' the WUR slowly until the pressure was at mid-point of the recommended range. System pressure, cold control pressure and residual pressure were also ok. (Note: I did not check the warm control pressure). The car was perfect!!!!!!.....so I thought.

Five weeks forward, the intermittent hesitation is back again. So far, the hesitation is not that bad yet. I will be checking again this weekend AND I WILL CHECK THE WARM PRESSURE . The car also takes 2 attempts before it starts.

I tried to this weekend to fix this but I was interrupted. Anyways, the car was used in the morning, parked at 9:00 a.m. and I started to remove the line from the WUR to the FD at 10:00 p.m. In removing the line from the WUR to the distributor, I noticed that there was NO fuel in the line. Is this normal? If not, what unit is failing causing 'air' to be in the line?

BTW, fuel filter is new, spark plugs are new, rotors and cap are new. As for vacuum leak, I have done the brake cleaner sweep and did not find any issues. I have measured the AFR at 2.8. Is this reading unreliable as I am possibly having vacuum and WUR issues?


In summary:

1. Is it normal to have a non-pressurized, no fuel, line between the FD and WUR?\
2. Could my issue be the warm pressure?
3. Does the '83 fuel pump have the 'check valve?' This appears to be inexpensive and I can replace this. (I can call Pelican tomorrow as I bought the unit from them).

Thank you guys!!!!!



Outside of my initial queries, and not that important for now, does anyone know the 'extra unit' inside an '83 WUR? I have searched the Web and all pics related to making a WUR adjustable did not cover this unit. Basically, this unit has an adjustment screw, electrified, and sits on top of the metal strip. Sorry I don't a pic.

[boyt911sc]

Originally Posted by cab83_750

In summary:

1. Is it normal to have a non-pressurized, no fuel, line between the FD and WUR?\
2. Could my issue be the warm pressure?
3. Does the '83 fuel pump have the 'check valve?' This appears to be inexpensive and I can replace this. (I can call Pelican tomorrow as I bought the unit from them).

Thank you guys!!!!!

Outside of my initial queries, and not that important for now, does anyone know the 'extra unit' inside an '83 WUR? I have searched the Web and all pics related to making a WUR adjustable did not cover this unit. Basically, this unit has an adjustment screw, electrified, and sits on top of the metal strip. Sorry I don't a pic.

cab83,

Answers to your question:
1). No! All fuel lines including the return lines should have fuel in them as soon as the FP starts to run.
2). Check your control pressures (cold & warm). No need to run the engine. This check could be done by jumpering the FP relay with ignition switch @ ON position.
3). The '83SC's FP has a built-in check valve. Check your residual pressure. A bad fuel accumulator will cause you to lose residual pressure too.
4). Check your system pressure and the FP's delivery rate or pressure.
5). Another important aspect in CIS troubleshooting that many over-looked is the vacuum leak. Not being able to find one does not mean you don't have one. One simple test to determine the integrity of your vacuum system is to let the car idle when completely warmed up. Remove the oil fill cap and observe engine RPM. If the engine RPM does not change (go down), you have unmetered air going into the system.
6). The multiple attempts to finally get the engine running could be caused by several things. CSV, low residual pressure, WUR out of spec, or even a leaking injector/s to name a few, could cause this problem.

Keep us posted.

Tony

Tony

[T77911S]

+1
air leak

tony, he opened the line 11 hours after last driving it, would he still see fuel in the line? he did say residual pressure was ok.


also,
fuses, does the interior light come on? fuse 18 i think(?)
frequency valve, is iti working?
O2 sensor?
CSV helps with cold starts


control pressures. you have to check cold AND warm. when the WUR goes bad, it is unable to vary the CP the full range from cold to warm.

[cab83_750]

OK. The car is beginning to really have startup issues in the morning.

Here are my test (Car is dead cold, electrical plug to the WUR disconnected, FP relay removed, jumper wire installed):

1. System pressure 66 PSI

2. Control Pressure 2.1 @ 15 deg using my outside thermometer (per Bentley, this appears to be the max/ceiling of the range).

3. Residual pressure: 23 PSI after 10 minutes
21 PSI after 30 minutes
As part of the residual pressure test, I opened the valve after 30 minutes and the PSI did not drop.

So, as a supplement, when I disconnected the line between the WUR and distributor today to hook up the CIS meter, the line was not pressurized/no fuel. I disconnected the distributor side first hoping to get a 'spray of fuel.' Unfortunately, not a single drop of fuel.

When I disconnected the line on the WUR side, there was a little fuel. As soon as I lifted the line, the WUR-hole has fuel in it to the rim.



Tony,

You said all lines should have fuel in them 'as soon as the FP starts'. My question is, "Should the lines be pressurized (fuel in them) after 8-12 hours?" I would think that the residual pressure means that this PSI should be there ALL THE TIME.

Also, what is a 'warm control pressure?' Do I start the car normally and see my control pressure change with the engine temperature? Can I use the dash-gauge as a rough thermometer.


I know that the residual test is for 30 minutes. Should I leave the CIS meter overnight and see what my pressure is? Would it harm the meter? I am planning on leaving it connected and see what my pressure is tomorrow morning.

Tomorrow, I will start the engine and remove the oil cap and see if I have an air leak.

[cab83_750]

Interior light is ok.

Frequency valve I have not checked.

O2 is disconnected (for years).

Is it even possible to remove the CSV valve to test it without dropping the engine?

I have power going to the thermotime switch. I have not tested it yet.

Originally Posted by T77911S

+1
air leak

tony, he opened the line 11 hours after last driving it, would he still see fuel in the line? he did say residual pressure was ok.


also,
fuses, does the interior light come on? fuse 18 i think(?)
frequency valve, is iti working?
O2 sensor?
CSV helps with cold starts


control pressures. you have to check cold AND warm. when the WUR goes bad, it is unable to vary the CP the full range from cold to warm.

[ossiblue]

I don't know the specs for your WUR, but 2.1 bar @15 degrees C seems too high. Again, I don't have the # of your WUR so I can't check the charts. My experience with the line to the WUR from the distributor (disconnected at the WUR) is that after sitting all night, fuel does not spurt, spray, or pour out and the intake to the WUR is full.

Note: You may wish to read the last paragraph first, as it addresses your current situation.

Here's what I did in a similar situation. First, I set the warm control pressure by running the car to operating temp and adjusting the round plug in the WUR where the fuel inlet/outlet are located. I found my warm pressure was too high so I disassembled the WUR and gently pressed the plug upward in the housing, from the inside of the open WUR. I reassembled everything carefully and mounted it back on the car.

Using the pressure gauge, I saw the cold pressure was now way too low, so I closed the valve on the gauge a bit to raise the pressure to spec for a cold start. Started the car, and let it get fully warmed, using the valve to "control" the rising pressure and keep it in spec.

Once warm, I slowly opened the valve on the gauge. As the pressure dropped, I gently tapped the intake plug down to raise the pressure to warm specs, then opened the valve a bit more. Repeated the process until warm pressure spec was reached with the valve fully opened. Now, the warm pressure was in spec. Caution: you must be sure the car is fully warm and that the bi-metal arm that raises pressure has reached its full arc.

Waited until the next day to set the cold pressure and did the typical "plug tap". If you find the cold pressure too low, you will need to disassemble the WUR again and push the plug up a bit--something you could do earlier when you push the fuel plug up.

Let the car warm up, and recheck your warm pressure and adjust, if needed.

One other thing. Once the above was done, the car started and ran beautifully--for about a month. Then, symptoms like yours arose. Checked the pressures and sure enough, the cold was out of spec. Reset and all was good for another month or so. Reset again, and put a little locktite on the cold pressure plug. That seemed to help. I guess there is something that allows the plug to gradually work its way up in the housing. That may be your issue too.

[boyt911sc]

Cab83,

There are too many things that could contribute to your problem/s. If I were doing this investigation I would start from the basic and reduce the guess-work to minimum. Let's begin with your start problem. My personal criteria for a well maintained CIS car is a start on the first try regardless of weather condition even in dead winter. Maybe a second try if the car has not been driven for several days.

Check:
1. Fuel delivery........the FP should be able to deliver 90+ psi (minimum) or about 2 liter/min flowrate.
2. All 7 injectors including CSV don't drip fuel at stand-by. Check injector pattern of the fuel. It should look like a conical umbrella of mist.
3. Control and system pressure within reasonable variance from spec.
4. Residual pressure.....minimal to no pressurized fuel in the system after a prolong shutdown. Do not know the minimum time but my experience showed 8 hours or more. The fuel line from FD to WUR will not hold pressure low enough because it is primarily a return line.
5. Electrical:
WUR & AAR gets power when FP is running
CSV gets energized @ START (cold)
6. Vacuum:
If you don't have a significant vacuum leak, the car should start with good ignition and sufficient fuel pressure.
Not being able to find or detect a vacuum leak/s does not mean there is no vacuum leak. Pressurizing the system @10 psi or less will reveal all the hidden leak/s.
7. WUR....control pressures could be checked without running the engine.
8. Never adjust the air mixture screw to facilitate starting. The unexpected change in mixture is mostly attributed to unmetered air and other factors. Adjusting should only be done for fine tuning when engine is completely warmed up. BTW, adjusting the mixture without a suitable gas analyzer is GUESSWORK!!

I'm no expert, but I haven't encountered a CIS problem that could not be diagnosed correctly. Except for the CDI and other electronics components, all the other CIS components could easily be benched tested by DIYer's like you and me. That's the beauty of CIS system. Keep the parameters within spec and it will run on demand.

The value of your system pressure is on the low side. I like to have somewhere in the 70's. Keep us posted and will get the problem sorted out sooner than you expected.

Tony

[cab83_750]

L.J.,

Bentley shows that my range should be at between 1.7-2.1 for an '83SC WUR.



So, here is an update:

1. As L.J. mentioned, it appears that residual pressure drops to zero (0) overnight. I left the gauge hooked up and in the morning, my PSI is 0. I guess this would be normal as I am going to assume that pressure gets built again as part of starting the car.

2. I was hoping that the car would not start this morning so I can check the CSV by disconnecting the red-black wire from the thermotime switch and hooking the same wire to ground. To my frustration, the car started after 2 tries. I will test again tomorrow morning.

3. While the car was running, I removed the oil cap and the car started to idle lower.

4. What I forgot to mention is that I have checked the AAV and it checks out ok. Borrowed my wife's make-up mirrow to see he moon

So, my next step is to check the CSV tomorrow.

[cab83_750]

Tony,

Thanks for the feedback.

When measuring the system pressure, the needle on the gauge is actually fluctuating/vibrating. I am probably closer to 68-69 if I were to take the high-side of the range. However, I am making a note that your preference should be at the 70's.

I do have a Gunson meter which I have IMHO used successfully for years. No guesswork here. I believe I have the tools, and parts (especially the WUR) are too darn expensive. I have rerouted my 'toy-funds' to my 370Z. (Enjoying and loving the Z, but deep in my heart I will always be a Porsche guy. Still watching at the Cayman-S prices as they have come down. I might sell the '75 that I am rebuilding and just buy a turn-key Cayman).

[cab83_750]

Early in the morning, dead cold, I disconnected both yellow and red wire on the thermotime switch.

1. Using my voltmeter, I hooked up the red wire to find the volt. Key in off or on position, no voltages. At cracking, I get less than 1 volt.
2. Using the voltmeter, I get the same when measuring the yellow wire. At cranking, I get less than 1 volt.

I am supposed to get 12 volts, correct? If I am supposed to get 12 volts, where do you think the disconnect is?

I went underneth to check the starter and all of my wires are hooked up.

[psalt]

If you do not have power at the yellow wire during cranking, the next step is to test at terminal 15A on the starter. I am not sure what problem you are trying to solve, but remember the CSV is irrelevent once the key is off Start and on Run. If your problem is cold running or drivability, the CSV is not your problem. Checking pressure on a lambda SC is only half the story, you also need to know what the FV is doing or it will not run properly.

[cab83_750]

Paul,

Not cold running.

My main issue that I am trying to solve is "morning start" issue. It takes forever to start the car in the morning; once started, everything is ok.....until the following morning. I can start the car by lifting the plate.

Based on all the 'morning start issues threads', my CSV may not be working.

[psalt]

I would just ground the red wire at the TTS bypassing it and try a cold start. If it does not improve, disconnect the CSV plug and test across the terminals, then check for power when cranking at terminal 15A on the starter. If the circuit is OK, then you must pull the CSV and test it. You may learn a few new words. It helps to remove the heater blower and use a mirror with a lump of clay to position it.

[cab83_750]

Can someone confirm my vacuum settings:

1. On the distributor, the nipple pointing to the fuse box goes to the back of the throlle body (closer to the firewall). Correct?

2. On the throttle body, there are two nipples facing me. One is closest to the 'lip/rim' of the throttle opening (top nipple). The other one is to the left of the 'top nipple' ; it is also lower than the 'top nipple'. Does the vacuum to the WUR connect to the top nipple or the bottom?

3. On the distributor, does the right nipple (facing the fan) connects to the top or bottom of the throttle body?

My car is CIS and my WUR only has one vacuum connection.


FYI, I do have the Bentley manual; however, based on threads here ---- either I am misreading the book or misreading the threads.

Thanks.

[Gunter]

Originally Posted by cab83_750

Can someone confirm my vacuum settings:

1. On the distributor, the nipple pointing to the fuse box goes to the back of the throlle body (closer to the firewall). Correct?

Yes, that's the vac advance

2. On the throttle body, there are two nipples facing me. One is closest to the 'lip/rim' of the throttle opening (top nipple). The other one is to the left of the 'top nipple' ; it is also lower than the 'top nipple'. Does the vacuum to the WUR connect to the top nipple or the bottom?

I think both have the same effect? One is for the WUR and the other is the vac retard. You may also have a vac valve in the line from WUR to TB?

3. On the distributor, does the right nipple (facing the fan) connects to the top or bottom of the throttle body?

Some people disconnect and plug this vac retard connection for better performance, i.e. run without vac retard.

My car is CIS and my WUR only has one vacuum connection.

FYI, I do have the Bentley manual; however, based on threads here ---- either I am misreading the book or misreading the threads.

Thanks.

When was the Ignition Distributor last cleaned and serviced?

[cab83_750]

Just to clear things up and update this thread: My morning issue is gone. My issue now is hesitation "WHEN I SLAM ON THE GAS PEDAL ." The hesitation occurs in 2-5th gears WHEN the car is warm. NO hesitation when cold.


Gunter,

Do you have an SC? Can you visually check which nipple on the TB connects to the WUR. FYI, one has strong vacuum compared to the other---Thanks. BTW, switching the connection of the WUR to the top and bottom makes a difference as far as severity of the stuttering.

The distributor has been cleaned 2 weeks ago. I even swapped out the pickup coil from another old distributor that I have.

[cab83_750]

Here are what I have done so far:

1. Fuel filter is new.
2. Fuel pump delivered the correct liters.
3. Tank is clean.
4. Disconnecting the rev limiter behind the gauge has no effect.
5. Injectors are new.
6. Plugging the WUR vacuum has no effect.
7. Relay next to the ECU is working. (I even have an extra one and has the same effect ).
8. Driving with a bad ECU relay has the same stuttering issue.
9. Spark plugs/rotors/caps are new.
10. I uninstalled my MSD setup (CDI/coil) and reinstalled factory. Same issue.
11. Electrical portion of the ignition was tested (replaced with an extra old one). Same issue.
12. Battery ground point and ground strap connection cleaned.
13. Frequency valve buzzes. When I disconnect, the car does rev differently. (I assume it works).
14. Removed the boot and TB openings were clean.
15. AAR has the moon opening when cold and fully close when hot.
16. Connected or disconnected, O2 sensor has not effect other than the fact that the car hunts a little bit when idling. FYI, I have been driving witht the O2 sensor disconnected.
17. Swapping the red pump relay with another one has no effect.
18. FP fuse was cleaned and working.
19. Ohm reading of the Magnecor wires are ok.
20. Vacuum leak test shows none. Taking out the oil cap changes the RPM.

Any more ideas?

Do I have a pin-hole vacuum leak which only shows up at quick WOT.

From Pelican database, there was a mention of 'swapping the battery' Would a faulty battery cause stuttering? I don't have any issues with lights/stereo, etc. so I an unsure if this is worth sourcing a battery for a test.

[cab83_750]

What I have not done:

1. I have not checked my valve adjustments. Adjustments were made 6 months ago and I have not put in many miles.

2. I have not replaced the fuel distributor head. $$$$$$$$

[Gogar]

When you say

7. Relay next to the ECU

Do you mean the Lambda relay under the pass. seat?

[cab83_750]

Yes. I have the original aluminum one, a new Bosch black one. Btw, screw the NAPA one; even though it clicks, it does not have any effects to the engine. This Napa model is my third one

When you say



7. Relay next to the ECU



Do you mean the Lambda relay under the pass. seat?