my submission for "CIS/Running problem" of the day
 

I've now lived with my car long enough to note the following pattern(s), I'm hoping this relates to one of the gurus enough to say "oh yeah, that's X, Y or Z...(or X, Y AND Z). I've been remiss in not managing to get fuel pressures so I'll take that lashing up front.

'78 3.0 Engine, in a '75, recent accumulator swap (old definately tested bad) didn't change the hot weather starting issue, I don't believe I have vacuum problems as there is major suction and big change in idle (but doesn't die) when I check the oil. I have plugged then re-attached the Decel Valve without any real changes in the narrative below.

Hot Weather (80-95°) best starting method requires "priming" the flapper in the air-box for 3-4 seconds. Twist the key usually 3 times with a "vroom"....then dies before it catches and settles quickly into a smooth idle. If I don't let her sit there and warm up for 3-4 minutes I get bucking and complaining and bad behavior, after this idle is steady about 900+, running behavior is smooth and strong, no backfire, no hesitation.

If I leave the car and re-start in say 15 min-1hr I don't have to do the flapper tickle but I have to give a bit of throttle to stay lit for a few minutes of running till it's fully warm again and then all is well.

Leave the car till lunchtime and I have to do the tickle again. If I don't do the tickle I can twist the key repeatedly till it floods and I have to open up the pop-off valve for a few min before it will start.

Cool Weather: (50-75°) I have had my car sitting for 2 weeks working on things, twist the key 4-5 times and it catches and idles (roughly, small amount of backfiring in the air-box here and there) for 2-3 minutes till it smooths out. Let it warm the 4 or 5 minutes and it's smooth as a baby. Now after it's fully warm (trip down the interstate or 6 or 7 miles away) my idle will climb to ~1800 and want to hang there.

I recall having to lean out the mixture when the weather got hot and richen it when it cools off. I am sitting here trying to remember which affect I got on what by adjusting for the warm high idle (I think it made the starting a bear if I brought it down). Tapping the AAV (?) will bring the idle down somewhat and a while back I sprayed some pb blaster on it and want to say it worked for a while....or maybe it got warm and I moved into the above state?

Obviously I have issues, probably in several areas (I appreciate sticking to the car related ones :) )

I agree that you may have several issues with your car, given your description.

First, as you already know (here it comes), you must test your fuel pressures!, all of them--system pressure, cold control, warm control, and residual. Your warm start problems smack of lack of residual pressure which is most likely from a faulty fuel pump check valve since you've already replaced the fuel accumulator. You don't want to throw money into random parts without diagnosing correctly and that requires a fuel gauge set. Do that first!

The cool weather hard start could be related to fuel pressures too. The hanging idle sounds like an air leak from a faulty device as you've indicated. The fact that you've messed with the fuel mixture to compensate for warm/cold conditions really complicates the situation.

Bottom line, IMO, you've got a problem with residual pressure, a problem with control pressures, an unknown fuel mixture setting, and a possible intermittent air leak. You need to get a set of fuel gauges and perform the basic system tests. Report your findings and go from there.

Without a gauge you will be tossing parts at it.

But, there is a cheap check valve in the neck of the fuel pump. It helps keep residual fuel pressure from falling below required starting pressure when the engine is warm and the cold start valve is out of the loop.

Last time I had one fail it was, 20 bucks.

I cave! have been stubbornly putting off buying that gauge set (I can't explain why... ordered the cheaper version last year from JC and it never came) for well over a year now but I just this minute placed an order for it from our host.

I will get it and some real facts and report back to this thread.

I replaced the odd Volvo fuel pump (with absolutely no check valve) with a good used [proper 911] pump and a brand new check valve last year. I have a long long set of stories on my sadly franken-porsche'd baby.

It's so frustrating that I have an "OK" running car but not a great running one. I have an all out refusal to drop it off to someone I don't know in [doubtful] hopes they know any more than I don't and a shoestring budget to work with, but a severe love for this cantankerous beast that puts a smile on my face every day I drive it.

Hey Travis,

Any luck with the pressure tests?

Shawn

I have the gauge set on my workbench, but work has been in the way for a couple of weeks. Need to research just what the he!!/where the he!! to take measurements :)

at the warm up regulator (WUR), remove the line going to the fuel distributor (FD). connect the hose with the shut off valve to the WUR, the other hose goes to the line to the FD. remove the power connector to the WUR.
find the fuel pump (FP) relay and jumper the relay so the FP runs witout having to start the car.
turn on the FP. with the valve open, that checks control pressure, closed checks system prssure.
once you have cold control pressure (CCP) and system pressure, connect power to the WUR and start the car. if you still have the thermo time valve (TTV)and if it is working, you should see a pressure jump about 15 seconds after starting, then it should continue to rise to around 3.6 bar. to test the vacuum circuit, you can remove the vacuum line to the WUR and the WCP should drop about .8 bar to around 2.8 bar.
to some up, you need to check:
system pressure
CCP
WCP with vacuum
WCP without vacuum

it would not hurt to verify timing and make sure the advance is working. also, check the condition of cap, rotor and plugs and wires.

Thank you so much for the detailed explanation, I knew I could find it on here somewhere but that's very helpful.

? - My fuel pump "talks" to me from the moment I hit the detent before start on the key, does that mean I don't need to fuss with the jumper bit?

- I do have a new cap, rotor and [good used] new plug wires. Plugs were new about 3k ago (I should check them). Timing is the one thing I've left absolutely alone on the car in fear of messing with one more thing that was working.

I'll perform the tests in the next couple days and report the readings.

Over come your anxiety.......
 

Just remember most of us here knew very little about CIS troubleshooting years ago. Today, with the advent of Internet, diagnosing the problems become easy and convenient. It would help a lot in your familiarization with the 911 engines if you have and read reference manuals. A digital camera is a plus.

Try to slowly overcome your anxiety or fear. The more you asked questions, the more you'll get educated about 911 engines. There is no such thing as 'stupid questions', but there are 'stupid answers'. Whatever problem/s you are having with your engine, it has been diagnosed and fixed a hundred times before. So it is not something new that would need research to fix.

You have been given sage advises and you are in good hands. These guys could help you with any CIS problems you could imagine. Whatever you do, for goodness sake, don't have a fire on your engine!!!! Oooops!!! I might have added another fear factor. Just joking.......go ahead and don't worry too much. It is easy and fun.

Tony

I would try bumping the idle up to 1000 and see if that helps. you will need to check the timing after and may have to adjust it slightly. The "flapper tickle" sounds fun.


quote

If I leave the car and re-start in say 15 min-1hr I don't have to do the flapper tickle but I have to give a bit of throttle to stay lit for a few minutes of running till it's fully warm again and then all is well.

The 75 did not use a fuel pump relay so you will not need to do the "jumper bit."

You are on the right path. Begin with the pressure tests and don't deviate or mess with anything else until you have completed them and posted the results. One thing at a time.

thanks ossi, i forget about that one.

i did not mean to imply to change timing, just check it and make sure the advance is working. its always good to get the basics out of the way.....like air leaks.

bumping the idle up could be a cover up. check EVERYTHING you can before making any adjustments.....or buying anything.

Ok, Hopefully you guys are still paying attention, here's my book report including videos.

Details: Car has been sitting for 3.5 days, started this morning out at ~55°.

Key on, nothing touched aside from connecting tester:
-Cold Control Pressure = 5.0-5.05 bar (oscillating that little bit)
-Cold System Pressure = 5.1 bar

Reconnected WUR, Started car, when it's this cool my "flapper tickle" (yes, it is fun, moreso inside the house :) ) doesn't seem to have the same affect so I didn't do it.

[Car Startup [see video]: MVI_2624.MOV - YouTube

post 15 minute warmup (car running):
-Warm Control Pressure = 5.1 bar (with Vac. line on)
-Warm Control Pressure = 5.1 bar (with Vac. line disconnected, no discernible change)

Turned car off after 20 minutes:
-Off, open valve = 2.6 bar
-Off, closed valve = 2.85 bar
(left the valve open at this point)
20 minutes later:
-Off, open valve = 1.6 bar

Key On Pressure test @ 20 min (still warm):
-(open valve) Control Pressure = 5.1 bar
-(closed valve) System Pressure = 5.1 bar

[Car Idled for 15 minutes (see video)]:
Fully Warm Runn - YouTube

shut off car, valve CLOSED:
pressure = 2.7 bar
Off @30 minutes later = 1.5 bar

4.5 hours later:
Off pressure reads 1.5 bar
Key On:
-(open valve) Control Pressure = 5.1 bar
-(closed valve) System Pressure = 5.1 bar

Note: Started car at this point (65° outside), just as hard to start as early morning, multiple key turns, ~5 minutes of bad idle and backfiring through intake and exhaust. After this it smooths out and is fine as in 2nd video.

so I'm open and grateful for suggestions, I have not touched the timing, I haven't adjusted the fuel mixture (slight richening reduced all the backfiring last winter when the air cooled off from our usual steam bath)

Travis

If your control pressure is the same as your system pressure, your WUR is not working. (moving the valve seems to not change anything in your results)
The high idle is most likely due to running the fuel head really, really rich to overcome the lean condition that your control pressure is trying to induce.

BTW.. where are you in Mobile? I go there a lot! Never see any air-cooled P-Cars though. I just figured they weren't' allowed west of Fairhope :)

You need to clean the filter in the Wur. It is plugged, giving you those pressures. If I recall is it below the fitting in the wur where the line from the fuel distributor enters the wur. Take the fitting out and it is a bronze looking thing in the wur. You can try some carb cleaner on it, you want to make sure it flows. Listen to what ossiblue has to say. That man saved me tons of time by reading his old posts. I had the same problem with my pressures when I started. Once you get it set up right the engine behaves so much better. Mine went from a hunting idle, popping, and generally poor performance to wow! Good luck!

Cold control fuel pressure...........
 

Travis,

The first few seconds of the first video confirmed my suspicion. The cold control fuel pressure is too high!!!! That's the reason you are having difficulties getting it to start COLD. I can't read the gauge (if that is 0-100 psi) and it should be around some where in the 20% - 25% of the gauge. The video shows more than 50% at the very start of the warm-up. Another culprit that would cause this very high reading at cold start is a clogged or restricted flow of fuel through the WUR and return line. Your cold control pressure is almost like the system pressure. That's definitely an anomaly.

The cold control pressure should be lower to allow the air flow sensor plate to rise up immediately upon START. And the system should start RICH not LEAN for cold start. Your fuel pressure at the very start is for LEAN condition already.

Getting the fuel pressure gauge kit is the best expense you'll have since owning this car. It will pay for itself after a couple of times using it. BTW, the air mixture setting is not changed when the weather changes from fall to winter. Good job.

Tony

It's reading 74-75 psi (yes 1-100 gauge), really through everything I've done so far as long as the key is on (running or not).

So my first step is to try and clean out that filter in the WUR and report back (before I touch anything else)?

No idea how much I appreciate the help.

WUR cleaning.........
 

Travis,

Dismount the WUR from the engine. Blow compressed air to the outlet port not through the inlet port. Why? You don't want the debris sitting on the micro mesh to get inside the diaphragm valve. You could blow air to the inlet after several passes of compressed air to the outlet. Do not attempt to remove the micro screen and do the cleaning in situ (micro screen).

http://forums.pelicanparts.com/uploa...1319982830.jpg

Tony

OK Guys, so I take a look in the WUR...daaaumm (see below)

http://forums.pelicanparts.com/uploa...1320531818.jpg

I find a big glob of rusty, mucky yuck. I cleaned it out, then I tried to blow back through as directed (that didn't work a bit). So I took it off, took it apart, finally after much carb cleaner and blowing through the tiny inside hole I do get [some] air coming back through the carb cleaner.

I have the feeling it's still clogged up though.

So I put it back on, reset to last week and start over. I still have exactly the same results (~75psi/5.1bar) on or off, WUR electrified or not. I start the car with same complaining as always. She's idling to warm at the moment just so she's been run this week but I still hear her coughing outside (after 10 minutes....it is colder today).

Is there further I can take that WUR apart to clean it out? Is it toast? What happens next, can I eliminate it?

Thanks for continued help,
Travis

That is nasty. You may end up doing a couple iterations of the cleaning once you get it going and get some volume of good gas through there.

I have never done this but did you take the four screws off of the base of the diaphragm from the inside to clean? This may be the absolute wrong thing to do. I don't know.

I do know if I blow in one hole or blow in the other hole on my spare WUR nothing comes through the open side. I think without pressure you will not get it to flow freely between the two. Edit - I am not saying to add pressure with an air compressor - I mean the fuel pressure opens it.

To clarify:

I did take off the diaphragm in the inside, I was able to (finally) blow a limited amount of air UP through the intake. After putting it back together I did now get air coming out of the intake when blowing in the outlet line (opposed to positively nothing when I started).

I held the theory it was FUBAR, how much worse could I kill it by taking apart as far as possible?

At what point do I start pondering getting rid of all the warm up equipment and using that pretty little red lever between my seats?

There are rebuilt WURs available.....RarelyL8.

Red lever is for warming up your feet, I believe.

You need the WUR - don't even think otherwise. Do you know if your 3.0 engine is a euro spec engine? I have a WUR that may be the correct one for your car. I can put it on my car and test the pressure specs. Not optimal given mine is old but it will do better than the one you have.

I think Joe Bob's suggestion is spot on. Given the prices of new and commercially rebuilt, I would consider alternatives if on a budget. RarelyL8 may rebuild the one you have.

This will brighten your day considering the gunk in the WUR:

http://forums.pelicanparts.com/porsche-911-technical-forum/272657-cis-fuel-distributer-cleanout-w-pics.html

Now might be a good time to post a picture of your engine, being it's a 3.0 in a 75. The reason being, the 75 does have the red lever for cold starts, but it is only hooked up to the accelerator cable. It will do you no good for your high fuel pressure problem nor with cold starts if it has been disconnected either at the cable or the micro-switch (which is probably not there anymore.) You likely have the later "automatic" warming system wired in--AAV, and AAR.

Back to your WUR. Bob has a good point about which WUR you have. Post the numbers when you can. From your description, it sounds like you may have cleaned out the port fairly well--if you disassembled the diaphragm and cleaned the two small port holes. The fact you still have high pressure can be due to damage to the diaphragms, debris still clogging a port, an out of adjustment WUR, or a block in the line back to the gas tank (BTW, have you tried to blow into the return line to see if it is clear back to the tank?) Easiest task is to check the return line.

The WUR is a simple device with the major problem being with the electrical heating element rather than the mechanical function of the diaphragm. I wouldn't give up on it yet. Double check that you reassembled the WUR correctly--especially the pin that goes into the hole at the base of the diaphragm housing. It is not difficult to reset the WUR to spec, now that you have a fuel gauge set. If you are willing to reset your WUR, let us know as there are several threads on how it's done.

Bob/Ossi

-I don't believe the throttle lever is hooked to anything right this minute (yes, Ossi is right, '75 that originally used it with a transplanted engine that doesn't) I think this transplant was wired in fully (I seem to remember testing at one point that I had power going to the AAR or AAV (whichever is sitting above #5) Sadly I can't speak to the origin or proper matching of much of my car.

-Tomorrow I'll take a few shots of the engine and it's numbers and post them. Here is one from last week zoomed closer if you are able to determine anything from it:
http://forums.pelicanparts.com/uploa...1320544219.jpg


Here is a shot I took earlier when I had the WUR out, if you can't read enough of the #s I'll get a better one tomorrow.http://forums.pelicanparts.com/uploa...1320543249.jpg

I will take whatever instruction and advice given before giving into the +$250 rebuilt option. I will check the return line tomorrow (just see if air will pass freely?) and will take the WUR back out and double check anything (I was as careful as possible reassembling back with the little pin in the divit and springs back under the cap).

......I feel like I'm on the precipice of a very slippery slope here, I've lived with this car and it's eccentricities for a year and a half and I thought it ran fairly well, but want it [at least closer to] right. My fuel distributor has a very slight seep in the split, I bet if I open it up it looks as bad as that thread Bob posted (or as bad as my gunked up WUR). Am I about to tear into a series of components that lead me to tear into more components till I write my own "Gold Plated Porsche" book?

Engine Photos/Numbers as requested:

http://forums.pelicanparts.com/uploa...1320603219.jpg


http://forums.pelicanparts.com/uploa...1320603230.jpg


http://forums.pelicanparts.com/uploa...1320603241.jpg


http://forums.pelicanparts.com/uploa...1320603251.jpg

Please excuse the nasty appearance of my engine compartment, I've only given it superficial cleaning until I have to drop the engine and do it all right.

It would seem the return line is blocked, can't seem to blow air through it a bit.

OK, so my diagram seems it's going back to the FD? (can't quite trace it back there at the moment)

The return line has a connection to the FD from the pressure relief valve, and a "T" connection for the line from the WUR. If you are trying to blow air from the WUR line, it should go back into the tank, regardless of the FD.

Since you cannot blow air through, first try to remove the return line going to the tank from the "T" connector itself, so you have only a rubber line to blow air through. Try again and if air goes through, you know the blockage is in the "T" connector. If air doesn't go through, you know the blockage is either in the hose, the line in the tunnel of the car, or the inlet port of the tank.

Gunk in the WUR likely means gunk elswhere so you may need to trace down several places. Again, don't get frustrated. You've already found the cause of your high pressure problem--a blocked return line--that's a biggie right there. Now it's a matter of following the line to uncover where the blockage is. If you need help on how or where to check the return line, post here and someone will chime in.

You're moving on!

Nope, not frustrated a bit, learning something and at least moving forward

Thanks for the help, I'll report back

As may be obvious my time to myself for tinkering is in short supply lately with some long work hours, a 3 year old maniac and a wife that likes some attention too.

I spent a little while trying to disassemble the "T" back from the WUR, trying to see if I could blow air forward to the tank. No luck at that so far so I'm still stuck with no clear answer as to just where my blockage is, I'll keep working on it.

....I decided to re-assemble my fuel lines so I could at least drive it once this week as I have for quite a while and when I took off the pressure gauge I found this:

http://forums.pelicanparts.com/uploa...1321221670.jpg

Does that mean what I think it means? Looks like rust to me, a tank removal and rehab in my future or???

my 911 had been sitting for four years and i had blockage at the return line in the fuel tank. I took weed eater plastic line and cleaned it out with it. it was easy to push it through.

Thanks, that's a good idea. I've been procrastinating further diagnosing that plugged line as I feel like I'm about to take the tank out and find all sorts of things which will have the car sitting dormant in the garage for several weeks (maybe less with a little time off at the holidays.

The weed whacker line is a good idea. You can pull the plug/filter out of the bottom of the tank to give yourself an idea if you have to pull the tank for cleaning.

21 gallon tank - and I bet it's near full.

I'm trying to run it low without konking out 2 miles from home (again) :D

...21 gal really? I swear I've never put more than 15 in and learned the hard way last year that a reading of <1/4 tank does not really mean 1/4 tank and that little light does work and ain't kidding.

Looks like the standard tank is about 16.38 US gallons and when the "G Program" car came out - Using my fingers to count through the years that makes 1977 - I think - there was an 80 liter 21.14 US gal tank fitted. In the early 70's the S had a tank that was nearly 30 gallons.

The low fuel light gives me about 40 miles. I think it is supposed to be about a gallon and a half reserve. Your owners manual will say.

HA! If I had one of those it might tell me what those confusing levers beside my steering wheel [are supposed to] do.

"16.38 gal" That makes much more sense to my experiences thus far.

funny story: Last year I noticed out of the corner of my eye that little light just starting to flicker as I pulled into my neighborhood, thought "huh, add one to the small list of "is working"". I quickly forgot that and a few days later went to show off my car to my visiting father. She coughed a bit under a full throttle pull on the way out of the neighborhood, coming back from a 3 mile quick trip she died at a light. 1/4 of a mile away from the house dies and wouldn't restart...Dad looks over says "Son, are you out of gas?" Doh! I'll not soon live that one down.

(I haven't actually seen that light since just for the record)