How to test CIS Fuel Pressure

[BB500]

I bought the fuel pressure tester today from Harbor Freight (along with a shopping cart full of junk that I was already contemplating returning on the way home.)
Well the extra junk was a must since Danglerb offered up a great 20% off coupon!

To get to the point,
Can someone write up how to check the fuel pressure before and after the fuel distributor on a CIS car and tell what the pressure should be?

This would help a lot of people in the future!

[american-kiwi]

BB500....its a easy test to do...let me take some pic's of the line you need to hook up to...and i'll post them for you...i can show you how to adjust the pressure too...i have a spare WUR

[american-kiwi]

guys correct me if im wrong?...im just trying to help BB500 ..not be a smart ass

this is the line you want (pic)...put the gauge set between this line...read this writeup...

http://www.porsche928forums.com/download/manuals/CISRebuild.pdf

it will help show which way the gauge shut off valve has to go on the line...but it doesnt show how to adjust the pressures...after testing and you see wrong pressures... take the WUR off the engine...turn it over...you will see a round brass plug under it...carefully remove the plug...and you will see a Allan key hole...find a key for it...then hook the WUR back up to the engine..but dont bolt it down, or you wont be able to get the key to turn......then if you need to adjust it...turn the key either way..re: pressures up or down...thats how i did mine
if your pump pressure is too high or low (closed valve)...you will need to add or remove some shims from the system pressure regulator on the CIS dizzy ...thats the fitting with the o-ring seals and spring inside..it faces the firewall

[devilinblack]

As I've pointed out before (I'm starting to feel like a broken record) the Harbor Freight kit does not come with the valve that's needed to properly test the CIS system. However, now that you've bought one let us know if it has all the adapters you need because if it does you could find/build a valve if you've got the time and inclination. Of course by the time you do this you're probably over the cost of just buying the right kit.

[rjm65]

I had come across this writeup for the WUR some time ago, they say to tap the bottom of the regulator in towards the center if the pressure is low, but you need to take the WUR apart to drive the regulator down if the pressure is high. It appears the WUR they used in the writeup didn't have the allen screw on the bottom. The allen screw seems more precise than tapping in/out for adjustment.

http://www.landsharkoz.com/images/pdf/wurfix.pdf

The writeup does do a good job of describing how to check the fuel pressure.



It does have a nice writeup on how to check the fuel pressure too.

[Danglerb]

Stephen are you talking about the T valve? I thought that was in there?

OTOH if its not, free rental of the pressure tester (return to HF).

BTW when I've seen a CIS tester used, the T fuel return line doesn't get hooked up, just goes to a gas can for dumping manually back in the tank when full.

[BB500]

I just tested the pressure the way you described WITH the Harbor Freight kit. It includes plenty of adapters to get the job done, devil.
Anyways, the pressure was perfect 75-77lbs between the top of the f.d. line and the WUR. It also holds pressure.

So now what? The car will start but not run. Where else should I check?

[american-kiwi]

BB500...have you adjusted the mixture yet?..the 3mm allan in front of the fuel dist'..its a little spring thingy...you might need to turn it up a little...take the air cleaner off...easier to do that way...clockwise rich...counterclock lean...it will fire with the startup cold valve (shot of fuel)...but be too lean to keep running...you'll need a long 3mm allan to do this...as you have to push the allan down to contact the adjuster...but dont push too hard, just hard enough to feel it grab the secondry adjuster inside ...get someone to help you...get them to startup the engine(keep starting)...till it will run with the adjustments...hope this helps you

[devilinblack]

Originally Posted by Danglerb

Stephen are you talking about the T valve? I thought that was in there?

OTOH if its not, free rental of the pressure tester (return to HF).

BTW when I've seen a CIS tester used, the T fuel return line doesn't get hooked up, just goes to a gas can for dumping manually back in the tank when full.

It's not just a T, which is what it looks like the HF kit comes with, it's an on/off valve for testing pressure with the valve closed off and with it operating. There are several tests outlined in the WSM and as near as I can see none of them just have it dumping into a gas can.

I've yet to check out those links that have been posted, but seriously now, has the WSM been consulted on this? Testing the CIS system is covered pretty thoroughly around page 25-5. You now say it starts but won't run, is it starting on its own or is it starting because you're putting ether/gas in the intake?

Sorry, but I'm a firm believer that testing needs to be done thoroughly and methodically otherwise you're no better off than just start throwing parts at the problem.

[BB500]

It will start on it's own, but just dies a second later.
I'm going to pull the tank in the a.m. and have it acid washed, following the advice of a friend

[american-kiwi]

did you try turning the mixture up?..to give it more fuel...dont be scared!...turn it 3-4 times... it will just run rich...if you didnt, and already your dropping the fuel tank! ,,,why?...you say you have 75+ psi!...there is one thing you may need to check in the WUR..remove the line fittings on the WUR..i cant remember which one has it, but inside the lines (in the WUR)is a screen filter..i bet thats blocked too........if you had read this before i edited this post sorry but...im trying to make this easy for you...you always seem to jump into the deepend everytime something doesnt work like you want....turning a screw is way easier than dropping a fuel tank first!
wish i was closer to you...would love to help you fix your CIS