Nathan

Would it be kosher, when I remove the return line from the accumulator to open the gas tank and use some compressed air to blow through the return line. I can put a regulator on it and regulate down to 20psi or even lower.

mfyoung1086

I would probably just disconnect the return line from the accumulator and from the cis and blow through that way

btw here's a good site for you to trouble shoot some CIS stuff, my real CIS knowledge comes from VW's theres not a whole lot of differences, but this site is 911 specific

http://jimsbasementworkshop.com/CIS/CIShome.html

Nathan

I use it. That's where I was looking for AFR (duh, air/fuel). Thanks for the help so far.

MillenniumFalcon

mf- thanks for the CIS resource!

mfyoung1086

Not a problemo guys, working on CIS systems is a lost art really, they confused too many people. Engineering wise they are not complicated systems, basically have some injectors always firing, that concept in execution requires lots of lil subsystems to work under different driving conditions, and those subsystems usually fail after 30+ years of use

Nathan are you still getting FP bleed after a warm shutdown? Also have you tried disconnecting the thermal valve?

I really think that FP bleed you're getting is causing the hard starts warm, as a thermal valve won't really cause a warm hard start, but it will effort the drivability of the car... when your running the car does the exhaust smell rich, like unburnt fuel?

Nathan

Pulled the fuel line from the bottom of the accumulator. Blew thru it, clear. started the motor for a few secs. Shut it off. Fuel didn't run out of the bottom of the accumulator, but it did dribble a bit. I checked for a check valve. I don't believe my model came with one. I think it is part of the fuel pump. One can be put onto the end of the fuel pump though.

Nathan

Pulled the fuel line from the bottom of the accumulator. Blew thru it, clear. started the motor for a few secs. Shut it off. Fuel didn't run out of the bottom of the accumulator, but it did dribble a bit. I checked for a check valve. I don't believe my model came with one. I think it is part of the fuel pump. One can be put onto the end of the fuel pump though.

mfyoung1086

How much is a bit? Like a few drops and it stopped?

Whats your FP like after shutdown now? 15 minutes after you shut down a warm motor you should still have 1 bar left in the lines, if not you're still gettting FP bleed

Nathan

yeah a few drops and it stopped. I left the line unhooked over night, and tried it again this afternoon. The car ran for a couple of minutes. The FP was sitting around 2.1bar. When I shut off the motor. I saw nothing come out of the fuel accumulator. The FP dropped to .8 bar immediately and bled off to zero within the minute.

Nathan

Haven't noticed the exhaust smelling rich. What would be a test for the thermal valve?

Nathan

My thermal valve is not connected by vacuum. Both pos have vacuum caps and the WUR has a cap on the port that goes to it.

Nathan

Finally got the accumulator replaced. The pressure bleed off is corrected. I'll have to drive it before I know if it took care of the rpms diving to 0 between shifts.

theiceman

sorry just catching up. definetly no fuel out of bottom of accumulator,.your diaphragm was sbot. this should help with warm starts. does your car idle at 950 ?
mine dies between shifts when i did the cis and found my idle screw way to far out. turned it in bout 3 turns and noticed idle didnt go up but solved my rpm drop off between shifts.

Nathan

Adjusted the mixture a little so the idle smoothed out (lean), and then adjusted the decel valve counter clock wise slightly. The rpm dive between shifts improved. We're on the up and up. I'll have to double check the pressures later.