CIS Pressure problem

[davis911s]

Scott don't feel bad. Like I said I am 100% confident that these parts worked in your car.

I don't think the lines are mixed up. The one on the left side is the supply the one on the right is the return.

I sent a small blast of compressed air down the line and that is how I heard the bubbling and knew the line was not blocked (I used a real small air compressor and about 60 PSI)

[Mysterytrain]

Is the plunger hanging up?

[davis911s]

Plunger able to move freely

UPDATE

I replaced the fuel distributor with my old one, since it showed good pressure readings. I left the air plate sensor in there, since it worked with the throttle body, therefore I assumed they were "in tune" together.

New readings perfect 4.8 and 1 bar

I was smiling thinking it would run perfect now. The throttle body and air sensor were working together. WRONG!

Engine stated then died after 1 second.

Tried to restart, it turned over then backfired (I have pop-off)

I pushed up on the sensor plate to activate the fuel pump and injectors. Engine started right up then died again 1 second later.

I pulled all 6 injectors (kept them hooked up) Placed the injectors in jars and disabled the ignition (plug wire) . Since it is fathers day I had my helper (4 year old son) turn the key to "Start" and watched the injectors, nothing, no fuel came out. This was about a 5 second try.

So I pushed up on the air plate sensor. All 6 injectors looked good with lots of flow.

Replaced injectors and tried starting again, same thing, started for 1 second and died. On re-start it turned over a few times and backfired. Pushed up on sensor plate to give injectors fuel and it started for 1 second and died.

QUESTION- Should the injectors not be flowing when the key is at "Start"??

I am getting there. I am still confused by the extreme high pressure on the other fuel distributor but not concerned about that right now. Just want the car to run.

I was thinking this is a lean condition. I half considered adjusting CO mixture but reconsidered because they worked together before, and I am not sure that is the problem.

I am thinking it is either;
1- Injectors not firing at start like they are suppose to, or
2- It is a lean condition and I need to start adjusting the mixture and idle screw

QUESTION- Should the injectors flow fuel when the key is at "Start"??

Shawn

[Jim Williams]

Originally Posted by davis911s

Checked the return line.
I blew air into the line and could hear it bubbling in the gas tank, it is not clogged

Then I used the spare return line and attached it to the fuel distributor and placed the other end into a jar.

Turned on the fuel pump and there is gas flowing into the jar.

So the excess is leaving the FD and the return line is not blocked.

What else can cause high system pressure? I am really confused

Thanks, and Happy Fathers Day

Shawn

Without knowing how much fuel is flowing into the jar, it's possible that the FD has a partial blockage, or the pressure regulator is mis-adjusted. What is the max pressure reading on your gauge? Possibly 100 PSI? The pump is capable of producing a much higher pressure than the working pressure of 70 PSI. So if the FD is regulating (fuel still exiting the FD under pressure) at 100 PSI, there could still be fuel flowing into the jar.

The FD regulator is really pretty simple. Fuel in, pressure builds until the valve opens at a pressure set by the spring, fuel flows around the valve and out the return opening back to the tank. Nowhere in the FD should there be any pressure higher than that set by the regulator. This includes the pressure indicated at the connection leading to the WUR.

If you want to check the regulator, you can remove the plug that holds in the spring, shims, and valve with the FD in place, but you will have better control of these parts with the FD out of the car. In either case, you need to exercise care not to lose the parts. The shims are very small, and thin. You remove them to lower the pressure, and add to raise pressure. One thing that may not be obvious at first is that the thickness of the washer under the hex on the plug that holds the spring in place will also affect the FD pressure setting.

If the FD remains on the car, it may be a problem to get the valve out.

[Paulporsche]

Maybe it's time to check other components like the AAV, the AAR and the thermovalve. Also check the airbox for leaks, as well as all vac lines, and the decel valve.

It sure sounds like it could be a lean condition. It could be caused by an improper mixture setting or vacuum leaks if not the FI components themselves.

Are all ignition components good? How about your points?

Why are you doing this? Did these symptoms recently appear? Is the car new to you?

[Walter_Middie]

I could not adjust the mixture and idle to get the car to idle under 2500. Without it stalling or running it really rich.

These are classic symptoms of an air leak. Without fixing the original problem, your new parts won't work well either. If you turn the idle screw all the way in, and it still idles high, air is getting in somewhere. A lot of people incorrectly richen the mixture to compensate so the car will run, but the idle is still high.

Your old parts may have been working OK. Did you check them with your tester before removing them? Would it worth the trouble to reinstall them to find where you issues are?

[boyt911sc]

Originally Posted by Walter_Middie

These are classic symptoms of an air leak. Without fixing the original problem, your new parts won't work well either. If you turn the idle screw all the way in, and it still idles high, air is getting in somewhere. A lot of people incorrectly richen the mixture to compensate so the car will run, but the idle is still high.

Your old parts may have been working OK. Did you check them with your tester before removing them? Would it worth the trouble to reinstall them to find where you issues are?

Rex,

I just cannot fully understand why some people recommended adjusting the mixture at this point. The 'leak condition' is obvously caused by some unmetered air going into the system. The idle screw does not do any change even at maximum adjustment. So this is an indication of 'excess unmetered air'. No CIS components could help solve this non-starting problem.

Go to basic CIS troubleshooting.....make sure you have sufficient fuel pressure, correct ignition timing and decent sparks, all CIS component in spec, and no big air leak, the engine would run. The system has a MAJOR AIR LEAK !!!!. A while back, a member ( who is very acrive in this forum) had a problem starting his car and focused on the WUR. It took a very long time to convince the fellow that there was undiscovered air leak in the CIS system.

Not being able to find the air leak does not mean there is no air leak (vacuum leak). There are several techniques used in locating vacuum leak/s. This should be the concentration of the work to solve this nagging no-start problem. Otherwise, it will be a long hot summer. Good luck.

Tony

[Paulporsche]

For the life of me, I can't imagine who Tony is talking about!?! LOL! Actually, I never denied there was a vac leak, I just pointed out that 3 mechanics and I couldn't find one.

I had several issues w/ my car recently, including several WURs, none of which wanted to rise from a cold cp, a thin spot in the metal tube feeding the AAR and AAV that opened up into a 3/16" dia hole when prodded w/ a screwdriver, an atmo line connected to the thermovalve instead of a vac line, a small 1/8" dia port on the lower backside of the TB that was not plugged, and finally, a faulty electrical connection to the WUR.

It's possible that some or all of these things, added together, produced an engine that was hard to start, and ran too lean, or started well and ran too rich. I don't really know if there was one or several culprits, but I'm glad I took the time to find all of these incorrect items. Turns out, for example, that 3 WURs I had actually had faulty bimetal strips, which could only be discerned by testing.

I don't know how big a hole has to be to be called a MAJOR AIR LEAK. As I said. I found a 1/8" dia hole and a thin wall in a pipe! Hardly seems MAJOR, but apparently it was enough. Or maybe it was enough in combination w/ the other items found.

Several people here are saying the same basic things, each in his own (in)imitable style: Make sure all ignition components are good, look for vac leaks, make sure the vac lines are correctly routed, test CIS components.

BTW I had to take the airbox and intake runners off the engine to find the hole in the metal pipe and the open TB port, so it may take some hunting.

Regarding the cold cp. I found that the ccp setting was very sensitive once it got down near the correct level. It seemed to take a large plug move to get very small or no change, and then very tiny moves to get large changes.

I asked before: did this happen w/ your old CIS components? Or is this something new since installing the new ones? I haven't read anyone recommending you change your mixture. Maybe Tony spotted something I missed, but are you sure your mixture was correct to begin with?

[davis911s]

I agree with you guys. I have made the decision to pull the complete system off the engine. Airbox and intake runners included. I have a big airleak somewhere. I am thinking airbox or that metal pipe that Paul had the problems with. I will see once I get it all taken apart.

The "used" system was tested before I bought it. It ran well on his car and it is actually his pressure tester that I have. He lent his tester when I bought the parts so that I could get my car going.

I will keep you guys updated

Shawn

[unclebilly]

Shawn,

Did you get it figured out yet?

[davis911s]

Scott

Not yet, I have not had a chance to work on the car. I just got an airbox tester in the mail from CIPOTIFOSO , two days ago. I will be testing the two airboxes next week.

Sorry I have been preoccupied trying to get my old VW bus running. It is my daily driver so more of a priority right now

[T77911S]

Originally Posted by davis911s

MORE PROBLEMS

Paul. YES I have a vacuum controlled WUR.

Problem keeps getting worst. I thought since I had a complete set that was from a known working car I would save myself some time and swap the known good parts over. Didn't work.

I swapped over the fuel distributor and the throttle body- since these both came from the running car I thought they would still be set up. Put everything in....no start I was able to get it to start by lifting the air flow sensor for a second thereby putting fuel into the system. But it would start and die right away.

I re-checked the fuel pressures using the gauges;
with the valve closed as soon as I run the fuel pump using the bridged relay the gauge needle wraps ALL THE WAY around the gauge until the stop.

Obviously the system pressure is WAY too high with these "new" parts.

What is going on? I am getting frustrated

I know that just throwing parts on something is NOT the way to fix things but I thought since the "new" parts worked this would be easier.

Also does anyone have the correct vacuum diagram for a 77 CIS? I found the one for a 78 on Jims website. The two I have had different vacuum connectors

This is how I have t right now- Front ports on throttle body- top one to bottom of WUR, bottom one to Thermo time switch and t to dist (plugged). Rear smaller plugs on throttle body plugged. Vacuum control was hooked up the same on both.

PLEASE HELP

the vacuum line from the TTV, (it is a thermo time valve, not a switch), goes to the rear of the TB down at the bottom below the throttle plate.

when you lifted the sensor plate and started it, did you hold it up to try to keep it running?

did you have the dizzy out before you started any of this?

[T77911S]

Originally Posted by boyt911sc

Rex,

I just cannot fully understand why some people recommended adjusting the mixture at this point. The 'leak condition' is obvously caused by some unmetered air going into the system. The idle screw does not do any change even at maximum adjustment. So this is an indication of 'excess unmetered air'. No CIS components could help solve this non-starting problem.



Tony

hey tony,
i dont think he was suggesting to adjust the mixture. he said to tutn the IDLE screw in. i have done kinda the same thing with carbs. i put my hand over the top to reduce the air intake to see how much or if the idle changed, a big air leak and you could almost competely cover a carb intake and it keeps running.

but now that i think about it, if he has swapped parts, the mixture may need to be set.
if he has no air leaks, i would try to get it running by holding the air plate up, even after it has started, and adjust the mixture to keep it running.
he has not said, or i missed it, what else was done before this. anything with the timing?

[sparkymart]

I Also have a 2.7 CIS with almost exactly the same symptoms.
I am also trying to debug the same issue.

Could i ask when you switch on the ignition does the fuel pump run constantly ?
( Mine does and i'm not sure this is correct )

Cheers
Martin

[T77911S]

the FP should not run when the engine is not running. if it is, the first thing i would check is the electrical plug on the back of the air low meter. if it is removed, the FP will run, this is also a good way to make the FP run when doing pressure checks.

[Walter_Middie]

when you switch on the ignition does the fuel pump run constantly ?

It depends on the year. Sounds like a 77 does not run all the time. My 75 does. You turn the key on and the fuel pump runs. The fuel flows in a constant loop from the tank to the pump to the FD and then to the return line and back to the tank to start over.

[Porsche_monkey]

Depends on whether or not your car has the air flow switch....or if it is bypassed.