fuel pressure

[onestar]

well i finally got my 928 running im working on adjusting the timing. but i ran into a problem. it seems like the engine isnt quite getting enough fuel. i checked the injectors they were good. so im thinking its the fuel pressure but looking through the manuals i cant find how to check the fuel pressure my 78 has the cis fuel system. if anyone knows how to check the fuel pressure and what the pressure should be i could use the help.

[Danglerb]

You need a special set of pressure gauges and adapters, Roger has some at Home - 928's R Us Porsche Parts Store .
How did you check the injectors for proper flow rate?

Pretty sure one of the Hawaii guys also has CIS, so you might be able to get some local help.

[MPDano]

CIS Gauges are a MUST to have. Take a pic of your Fuel Distributor, most are non-adjustable but some are. For the most part, all your adjustments will be on the WUR (Warm Up Regulator), which is really a Control Valve.

[Rupesy]

I just got done checking mine on my '79. I posted pics of where you can hook them up on the WUR. I believe the pressures are a little different depending on US or ROW. Mine is essentially around 20 psi cold and around 50 psi warmed up. I bought mine from JC Whitney. I also posted a link of the test kit for reference (on a volvo, but the pic shoes the test kit and other helpful info). Some people have not had success with this tester, however, I have used mine many times. This one has lots of adapters and I did not have to buy any additional fittings. The point is you need to get yourself a tester first.

Using the K-jet Fuel Pressure Test Kit

[onestar]

to answer danglerbs question i didnt check the flow rate of the injectors all i did was with the caron i uscrewed the injectors just to see if they had any flow they all did ill get pics of the fuel distributer as soon as i can got shcool for the week so idk when ill have a chance thx for the help

[JK McDonald]

Hey Onestar, Like Danglerb, MPDano and Rupey have indicated - it is almost impossible to troubleshoot a CIS system without the proper gauge setup. There are just too many variables involved if your problem turns out to be a fuel pressure issue.

One rough test (without running your engine) that you can make is to check the spray pattern and fuel delivery of your injectors. Just get 8 pint size clear plastic milk or juice bottles. Clean them out - point an injector into each bottle - jumper your fuel pump relay to send power your fuel pump, turn the key to on - then manually lift your air plate for 10 -15 sec.

Part 1) Compare the active spray pattern of each injector - turn your key off -

Part 2) Measure the level of the fuel in each bottle for an (approximate) equal amount.

Although this test is a bit crude it can help to indicate any injector that may need attention. Naturally, it is recommended that this test be carefully performed by a non-smoking participant…..

Good Luck, Michael

[Danglerb]

CIS specific gauge set, normal fuel injection gauge sets won't have the right configuration or adapters.

AND

Fire Extinguisher.

[MPDano]

Originally Posted by Danglerb

CIS specific gauge set, normal fuel injection gauge sets won't have the right configuration or adapters.

AND

Fire Extinguisher.

Mine did. The strange thing is that I can no longer find my set for sale. I tried last year to look for it, for another user who needed a set, no go.

[Danglerb]

Roger has a good set and good deal, I would look no further.

[MPDano]

Originally Posted by Danglerb

Roger has a good set and good deal, I would look no further.

There ya go!

[karlruiter]

Hi onestar
I am in honolulu and have a CIS gauge set, some CIS spare parts and a fair amount of experience with the CIS on the 928 (although my '79 is STILL not running perfectly). Happy to help out if I can. I'm not a frequent user here (generally on rennlist, but bdangler sent me over) so if you want to hook up contact me via my yahoo email. k_ruiter@yahoo.com.