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Angry Hard Start when cold, Hard Start when Hot

Hi Pelicans:

I had posted this info earlier this month, and I was encouraged to start a new thread (I had exhibited bad manners and jumped into another Pelican's thread, won't do that again!).

I posted originally in a "Hard to hot-start" thread, but now I also have to crank for what seems like a long time when cold, and then the engine barely catches, and then settles into a good idle. Right now, it's firmly in the "annoying" behavior, but I am worried that my fuel system will progress into the "unreliable" category.

I spread the posts on my fuel pump relay a bit as a simple fix, but no changes to the hot start issue I had.

Pressure test is as follows (note, the vacuum line from the WUR to the airbox was disconnected when I did this test, and I've since attached it, could this be the source of the low cold pressure?).

1 - '83SC
2 - US model
3 - -090 WUR, but tinkered with by my local wrench about 2 years ago
4 - 20 deg Celcius
5 - 25.9 Ohms resistance
6 - 4.4 bar system pressure
7 - 0.6 bar cold control pressure (***seems low, yes?)
8 - 3.5 bar warm control pressure
9 - 5 min 30 sec to reach warm pressure max
10 - residual pressure @ 5 min - 1.7 bar
11 - @15 min- 1.5 bar
12 - @30 min - 1.4 bar
13 - @60 min - 1.3 bar (just did this once)

Things I've considered, but not yet done include: replacing the fuel filter (it's time anyway), replacing the fuel accumulator (but the system seems to hold pressure, based on my reading above, correct?), and possibly redoing the electrical connection to the WUR (there's electrical tape on it from some PO adventure). I also have a new cold start valve handy if it comes to that, I hear it's a bear to replace with the engine in.

Open to suggestions! I really enjoyed when I first had the car, I barely cranked the engine and it roared to life, loved that!

Thanks for your help Pelicans!
Old 09-21-2017, 11:00 AM
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Additional troubleshooting info - I just went for a drive, view clip to see what I mean by hard start.

https://youtu.be/yJJtk5zBHss

You can see that the car settles to a nice idle immediately of 900RPM. However, after about 2 minutes of idle the RPMs drop over the next 2 minutes (so 4 min total) to about 600 RPM, with associated stumbles. I can drive off and once the engine is fully warm (oil temp needle at the 9 o'clock position) the RPMs are once again at 900.

Any ideas?

Thanks!
Old 09-21-2017, 12:19 PM
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Check timing
Old 09-21-2017, 03:20 PM
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You need to have the WUR plug bumped.

Your CCP is too rich. S/B between 2.0 and 2.5 bar at 20C.

Take the easy route. Pull off the WUR, send it to Tony and it will be done in a week.

He can probably source a new connection for you as well.

2nd post is a cold start, yes? Appears to be.
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Old 09-21-2017, 03:21 PM
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For grins, plug the vacuum retard hose with a fat nail or golf tee where it plugs into the vacuum unit on the distributor - closest to the center of the big fan. Don't worry about the open port on the vacuum port. No impact with line plugged. No touchie on the other one, tho.

Might help your start-up rpm's go up a little higher as per design.
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1981 911SC Targa
Old 09-21-2017, 03:33 PM
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Read your hot start thread. One step at a time.............

You should not have a hot start issue with circa 20 psi after an hour. 1.3 bar. Just talking.
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Last edited by Bob Kontak; 09-21-2017 at 03:43 PM..
Old 09-21-2017, 03:40 PM
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Let by gone be by gone..........

Quote:
Originally Posted by garment View Post
Hi Pelicans:

I had posted this info earlier this month, and I was encouraged to start a new thread (I had exhibited bad manners and jumped into another Pelican's thread, won't do that again!).

I posted originally in a "Hard to hot-start" thread, but now I also have to crank for what seems like a long time when cold, and then the engine barely catches, and then settles into a good idle. Right now, it's firmly in the "annoying" behavior, but I am worried that my fuel system will progress into the "unreliable" category.

I spread the posts on my fuel pump relay a bit as a simple fix, but no changes to the hot start issue I had.

Pressure test is as follows (note, the vacuum line from the WUR to the airbox was disconnected when I did this test, and I've since attached it, could this be the source of the low cold pressure?).

1 - '83SC
2 - US model
3 - -090 WUR, but tinkered with by my local wrench about 2 years ago
4 - 20 deg Celcius
5 - 25.9 Ohms resistance
6 - 4.4 bar system pressure
7 - 0.6 bar cold control pressure (***seems low, yes?)
8 - 3.5 bar warm control pressure
9 - 5 min 30 sec to reach warm pressure max
10 - residual pressure @ 5 min - 1.7 bar
11 - @15 min- 1.5 bar
12 - @30 min - 1.4 bar
13 - @60 min - 1.3 bar (just did this once)

Things I've considered, but not yet done include: replacing the fuel filter (it's time anyway), replacing the fuel accumulator (but the system seems to hold pressure, based on my reading above, correct?), and possibly redoing the electrical connection to the WUR (there's electrical tape on it from some PO adventure). I also have a new cold start valve handy if it comes to that, I hear it's a bear to replace with the engine in.

Open to suggestions! I really enjoyed when I first had the car, I barely cranked the engine and it roared to life, loved that!

Thanks for your help Pelicans!


Michael,

This would be the very first time I have responded to your posts 3 years after I turned over the car to you. The car performed flawlessly for a year until you or someone started tinkering it. I will not dwell what occurred between us on the day you got back the car and I have learned to ignore and forget about it.

Life is too short and I have buried the hatchet. If you still need some CIS assistance, first you need to do is have the WUR tested and evaluated. Send it to me and I will test and calibrate it. I don't recall that the WUR I installed in your engine was "adjustable". It must have been converted later on.

Tony
Old 09-22-2017, 04:44 AM
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Agree. So I am leaning towards something electrical for the hot start issue, as in, the connections get heat soaked and do not allow the components to function/function optimally...is this possible?

Quote:
Originally Posted by Bob Kontak View Post
Read your hot start thread. One step at a time.............

You should not have a hot start issue with circa 20 psi after an hour. 1.3 bar. Just talking.
Old 09-22-2017, 06:34 AM
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Quote:
Originally Posted by garment View Post
as in, the connections get heat soaked and do not allow the components to function/function optimally...is this possible?
I only have one related story. A member's car in Houston on blistering hot days would break the connection going to the freq valve from the Lambda box at the 12 pin connector between the rear shocks. It ran really bad. Coughing, low rpm, could not rev the engine w/o backfire.

Cool down all good.
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Old 09-22-2017, 07:47 AM
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Quote:
Originally Posted by garment View Post
7 - 0.6 bar cold control pressure (***seems low, yes?)
My apologies to the experts for speaking out of turn, definitely not one here.

If you have an adjustable WUR, you can adjust the cold pressure to spec.

CIS Troubleshooting for Dummies

Quote:
8 - 3.5 bar warm control pressure
9 - 5 min 30 sec to reach warm pressure max
10 - residual pressure @ 5 min - 1.7 bar
11 - @15 min- 1.5 bar
12 - @30 min - 1.4 bar
13 - @60 min - 1.3 bar (just did this once)
These look fine to my amateurish eyes and points to something electrical spark related.

Good luck.
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Old 09-22-2017, 08:49 AM
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Quote:
Originally Posted by garment View Post
Pressure test is as follows (note, the vacuum line from the WUR to the airbox was disconnected when I did this test, and I've since attached it, could this be the source of the low cold pressure?).
Nope. This is just a vent. See post #8 from Jim Williams.

WUR Vacuum on 82 911 SC, what does it do?
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Old 09-22-2017, 11:20 AM
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Thank you Tony, for the very nice offer. Id be happy to take you up on it. Ill send the WUR along with a return shipping label.

Quote:
Originally Posted by boyt911sc View Post
Michael,

This would be the very first time I have responded to your posts 3 years after I turned over the car to you. The car performed flawlessly for a year until you or someone started tinkering it. I will not dwell what occurred between us on the day you got back the car and I have learned to ignore and forget about it.

Life is too short and I have buried the hatchet. If you still need some CIS assistance, first you need to do is have the WUR tested and evaluated. Send it to me and I will test and calibrate it. I don't recall that the WUR I installed in your engine was "adjustable". It must have been converted later on.

Tony

Last edited by garment; 09-22-2017 at 05:09 PM..
Old 09-22-2017, 04:59 PM
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Quote:
Originally Posted by garment View Post
I really enjoyed when I first had the car, I barely cranked the engine and it roared to life, loved that!

Thanks for your help Pelicans!
What was done that caused that to change?


Cheers,

Joe
Old 09-26-2017, 06:11 AM
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WUR-090 going back home........

Michael,

The package containing your WUR is on the way to MD. My wife had surgery yesterday and everything looks good. And was not able to go home till this morning (Tuesday). Made an excuse to get a shower, actually I wanted to get your WUR back to you ASAP as I promised. I will stop by the FedEx branch to have your WUR shipped on my way back to the hospital later today.

Both the CCP and WCP were out spec and re-calibrated back according to specification. I am not sure what was your problem that prompted you to tinker the WUR because I never read your posts for the last 3 years except one.

Anyway, if you have any starting or running problem after installing the WUR, you have another unknown culprit to tackle. Keep us posted.

Tony
Old 10-10-2017, 07:33 AM
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Thank you so much Tony and very glad to hear your wife is OK.

Please check your email, and if you can't use the gift I sent, get something nice for your wife!

Michael

Quote:
Originally Posted by boyt911sc View Post
Michael,

The package containing your WUR is on the way to MD. My wife had surgery yesterday and everything looks good. And was not able to go home till this morning (Tuesday). Made an excuse to get a shower, actually I wanted to get your WUR back to you ASAP as I promised. I will stop by the FedEx branch to have your WUR shipped on my way back to the hospital later today.

Both the CCP and WCP were out spec and re-calibrated back according to specification. I am not sure what was your problem that prompted you to tinker the WUR because I never read your posts for the last 3 years except one.

Anyway, if you have any starting or running problem after installing the WUR, you have another unknown culprit to tackle. Keep us posted.

Tony
Old 10-10-2017, 12:08 PM
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Took your advise here once Tony offered. WUR is now on it's way back to me. Will advise on status on/after Wednesday of this week. Thanks for hopping in!

I'm holding off on a new connector, Spoke with Timmy2, sounds like daisy chaining the connector is a bear, so a last resort thing.

Quote:
Originally Posted by Bob Kontak View Post
You need to have the WUR plug bumped.

Your CCP is too rich. S/B between 2.0 and 2.5 bar at 20C.

Take the easy route. Pull off the WUR, send it to Tony and it will be done in a week.

He can probably source a new connection for you as well.

2nd post is a cold start, yes? Appears to be.
Old 10-10-2017, 04:52 PM
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Had the injector sleeves changed out, they were past it and leaking air, but that was months ago. Local wrench made the WUR adjustable. Maybe I just knocked the pin in too far when tinkering? Let's see what happens, I will reattach the WUR this week. Thanks.

Quote:
Originally Posted by stlrj View Post
What was done that caused that to change?


Cheers,

Joe
Old 10-10-2017, 04:56 PM
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Installed the WUR tonight. Couldn’t go for a drive but let the car idle a bit and def didn’t have the drop in RPMs that I had before. Still took two cranks to start, but I associate that with the dry WUR on the first crank.

I think I am in a better place. RPMs were a bit low, but I didn’t have a chance to run the car up to operating temp, plus the ambient temps are much colder than when I did my last pressure test. Regardless, thanks to Tony for calibrating the unit!!

I’ll be at a C&C or two this weekend and will report back.

Quote:
Originally Posted by boyt911sc View Post
Michael,

The package containing your WUR is on the way to MD. My wife had surgery yesterday and everything looks good. And was not able to go home till this morning (Tuesday). Made an excuse to get a shower, actually I wanted to get your WUR back to you ASAP as I promised. I will stop by the FedEx branch to have your WUR shipped on my way back to the hospital later today.

Both the CCP and WCP were out spec and re-calibrated back according to specification. I am not sure what was your problem that prompted you to tinker the WUR because I never read your posts for the last 3 years except one.

Anyway, if you have any starting or running problem after installing the WUR, you have another unknown culprit to tackle. Keep us posted.

Tony

Last edited by garment; 10-13-2017 at 02:55 AM..
Old 10-12-2017, 07:33 PM
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Early morning start-up........

Michael,

Please do these tests for me:
a). Start the engine. Don't depress the gas pedal. Record how many attempts before you could get engine to run.
b). If you have a CIS pressure gauge record the very initial CCP and engine RPM.
c). How long does it take to get the CCP to WCP? The time or duration is temperature dependent. Take note of the ambient temp. (approx.)

A source on unmetered air going into the system is something you should be aware off. They all leak, it is a question of how much. Keep us posted.

Tony
Old 10-13-2017, 06:13 AM
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Bob, I've installed the re-calibrated WUR from Tony and I don't have great results to report back (I'm replying to Tony shortly). I've plugged the hose you suggested and will see about results/differences tomorrow.

Quote:
Originally Posted by Bob Kontak View Post
For grins, plug the vacuum retard hose with a fat nail or golf tee where it plugs into the vacuum unit on the distributor - closest to the center of the big fan. Don't worry about the open port on the vacuum port. No impact with line plugged. No touchie on the other one, tho.

Might help your start-up rpm's go up a little higher as per design.
Old 10-15-2017, 04:44 PM
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