he_mech_usmc

Good or bad, I don't know, but I have a k-jet car. I got back at it tonight by checking "warm" control pressure, 5.1 bar, system pressure was approx 5.15 bar, was fluctuating between 5.1 and 5.2...don't know exactly what that means, but I don't think that it's right. WSM section 25 in manual 1a on page 25-5 and 25-6 says system pressure to be 5.2-5.8, "warm" control pressure 2.8-3.2 bar. Any ideas guys?

Thanks,
Josh

jpitman2

Usual answer - most likely a blocked wur. follow watson's check list :-
1. loosen outlet of wur, check for fuel coming out and drop in control pressure. If no drop, wur is blocked.
2. if not wur, move to next union - at fuel distributor. loosen, check for pressure drop; if no drop, line back to wur is blocked.
etc - you may get all the way back to the tank return line , which should be checked for good flow.
Try loading tank with solvent like berrymans oil, bridge pump relay and leave run (while you remain close by with extinguisher!) for as long as you can to try to flush crud out of lines. Has some work been done lately, or has it been standing for a period? See other recent posts on this - there are fine brass gauze filters in inlet of wur - best cleared ultrasonically, or by removing the filters and burning the crud off. See notes at ferrari400.com on wur insides. Dont try to adjust anything yet, get it clean, and pressures stable. Also do a flow test - open return line over rh fender, feed into container - should see ~1350ml/30 secs.
jp 83 Euro S AT 54k

danglerb

Not a CI$ guru, but I know you need a set of CI$ gauges with the T and shutoff valve to measure relative pressures between the devices.

linderpat

Here are two good resources to keep on file if you have a CIS car:
http://www.ferrari400parts.com/Warmu...atorrepair.php
http://www.mediafire.com/?j4cdfaaqiqggcw5

SMTCapeCod

For some additional context....OP has been showing a lot of mettle and trying to gain some advice/input from folks at another venue. He's been through the WUR, and the FD and found a couple of blocked (!) fuel lines so far. This doesn't change the value of guidance provided, just want to establish that he isn't just cracking into it.

With the screens pulled from teh WUR and given indications of material obstructions, that Union in the FD fuel feed is very very often a culprit. Did you also check for screens/blockages in the FD ports for each line, when you had it apart?

There is a scan of or a link to the pressure curves in the Technical Specifications book, I found that to be more helpful than the manual but it may not be for your appliaction.

he_mech_usmc

SMT- When I was through the FD, I did check the inlet screen, it was totally clogged...cleaned it out and then moved on to the next part I thought I needed to check, I have not checked the individual screens on each injector line...when I get home tonight I'll get out there and check the WUR screen and the individual screens to each injector line. I'll also go out and check the flow from the FP if it's not raining.

I have been looking in the WSM that I downloaded from AO's signature line...it does get a little confusing, however I did find the section that was specific for 78-79 automatics they are the pages that I provided above...when checking flow should I use the flow spec for 2 pumps since that is what my car originally was designed with or just one since the intank pump has been removed by the PO?

Linderpat- thanks for the links, I have the WUR rebuild, but I did not have the Bosch k-jet manual.

Dangler- I used the CIS gauge.

Thanks,
Josh

Jadz928

Don't check 'em, chuck 'em. Easy to get out without damage using the right size torx driver.

he_mech_usmc

Jim- one was loose when I resealed the FD, I checked it and it was clear...be home in about an hour and I will be getting those out and checking the WUR screen...if they're not blocked...guess it's on to checking the injectors for blockage. I know that the return line from the WUR is clear, I had taken it out and cleaned it when I did the injector lines.

Thanks,
Josh

karl ruiter

10 second overview of the CIS system:
The amount of fuel going out to the cyls is determined by the position of the control plunger. As it moves up more of the metering slits are exposed. Two forces are acting on the control plunger: the air metering plate wants to push it up and the control pressure wants to push it down. So higher control pressure= less fuel.
10 second overview of the control pressure:
The pressure from the pump goes through the system pressure regulator which screws in the side of the FD. One of the places it goes after that is the control pressure feed, via a very small hole (0.03"?) in the gasket between the two halves of the FD. The small hole limits the flow and creates a pressure drop that depends on how much is flowing through it. Then the control pressure lines go to the WUR where there is a screen and a diaphragm. The screen creates a fixed pressure drop that just depends on flow rate and the diapragm creates a pressure drop that depends on the position of the WUR plunger and flow rate. The position of the WUR plunger depends on temperate and vacume. Fuel leaving the diapghram just goes back to the tank. So the control pressure is set by the balance between FD supplying fuel throught he feed orifice, and the WUR draining it away through the screen and diaphragm.
So if you control pressure is way too high (sounds like it is) then the problem could be either with the FD supplying too much fuel or the WUR not draining away enough. If the car has not been heavily molested then it is probably the latter, and probably the screen, but if the car has been worked on by people who didn't really know what they were doing then it could be anything in the circuit.

SMTCapeCod

Wish I were home in Mass I would probably be able to slide some parts you could just bolt in place of what you have to help isolate/monitor changes. No such luck though, won't be back up there for a while.

IcemanG17

I tried "tuning" a CIS car on a dyno...it was a "learning" experience.....while the car ran fine low through midrange it was became quite lean up high....NOT good, especially for a race car.... The significant downside was as we increased the fuel (screw in plate) it didn't change much up top, but nearly undriveable at idle.....it appeared to run out of fuel up top no matter what we did....but the idle ALWAYS got FAT...silly fat...like 10.8 AFR fat.... We ended up changing it back to its original settings....still a bit fat at idle, and still lean up top.....

What I learned....my L jet system is WAY BETTER.... you can adjust the spring tension on the AFM for noticeable improvements in AFR across the board...like near 1.0 AFR more rich improvements....plus the ability to increase fuel pressure with an adjustable regulator.....much more range of adjustment

jpitman2

I may be wrong, but I doubt blocked injectors will affect control pressure, unless there is a back door from the injectors to the WUR line ? By that I mean that if system and control are in spec (hot and cold control), and it wont start or run well, then look at injector lines, and injectors.
jp 83 Euro S AT 54k.

steve322s

Before you get to deep check the hoses for the fuel gauges your hooking up. I purchased a new set from harbor freight, showed system pressure due to a shreader pin in the hose not working! in the long run i took appart a wur that was working. may not be your problem but may save a lot of unneccasary work.

Good luck

he_mech_usmc

I didn't mean to imply that the injectors were the cause of the pressure issues, just that based off of the junk I got out of the lines there may be a couple of frozen up injectors....my gauge hoses do not have schrader valves in them, but thanks for the heads up.

Thanks
Josh

Luis_M

It would be helpful if you also listed your cold pressure and outside temp.

After refurbishing my wur cp and wp were in spec but stray fine debris in the system took a few days to work its way through and my warm CP slowly climbed from spec warm pressure to way too high. I wound up pulling the Wur about 3 or 4 times and flushing inlet with carb cleaner while holding it upside down then putting it back in. I left the gauges hooked up for about a week and finally disconnected them when the pressures were stable for several engine runs. I also cleaned out the Fd and all the engine bay fuel lines and had new ff before running first time so this junk was probably in the accumulator or lines between ff and firewall. Its been running perfectly for nearly a year now

1981 Euro S