| Author |
Message |
David Prall (Davidpra)
Junior Member
Username: Davidpra
Post Number: 95
Registered: 2-2001
| | Posted on Tuesday, June 25, 2002 - 6:18 pm: | |
While Brian S. is obviously a sharp guy, my typo of "Brain" was purely accidental. LOL |
David Prall (Davidpra)
Junior Member
Username: Davidpra
Post Number: 94
Registered: 2-2001
| | Posted on Tuesday, June 25, 2002 - 5:29 pm: | |
Brain is correct and on the right track. Forgive the forthcoming sermon. But, if it weren't necessary, I wouldn't have so many people bringing me their cars in desperation after Ferrari dealers and various mechanics were left "stumped" (and a lot richer).
BOSCH CIS - BASIC 101:
The K-Jetronic (in your 83 Boxer) and the later KE-Jetronic CIS systems utilize a "secondary pressure regulation" system and a "primary pressure regulation" system to control fuel pressure and influence fuel mixture.
The "secondary pressure regulation" system consists of: (depending on application) warm-up regulator(s) / differential pressure actuator (s), thermo-time switch(s), and the ECU (or, oxygen control unit). The cold start valve, relay, and temp switch actually function ancillary to the pressure regulation system; and, while they do affect mixture, they do not affect pressure.
That understood, the functionality of this secondary regulation system is really just to "trim" the primary system pressure --- it does not dramatically alter primary pressure whether hot, cold, properly functioning, mal-functioning, or even disconnected (any CIS equipped car will run with these things removed --- but it will be rich / lean as a result).
The parts of the "primary pressure regulation" system that actually set, control, and dramatically influence fuel pressure are: the fuel pump, the fuel filters (to a degree), and the system pressure regulator device (either a tapered screw / valve seat assembly in the fuel distributor; or, a vacuum diaphragm / spring assisted plunger / seat assembly external to the fuel distributor).
NOW, FORGET ALL THAT CRAP, AND FOCUS ON THE BASICS.
You're car will not start or run. So, either there is "bad" spark delivery or "bad" fuel delivery. First off, confirm you have ignition --- use an inductive timing light on a few plug leads (make sure you sample one from each bank). For now, don't worry about correct timing ---- any rhythmic spark is good to go. Next, check the primary system pressure --- use a pressure gauge at the appropriate tap on the fuel distributor(s).
If this pressure is in spec, and you have a spark, your problem is most likely fuel metering. And, I don't mean secondary system malfunctions ---- these will not prevent the car from starting or running!!! ---- these will merely cause the car to start or run poorly. What I do mean is that the system "basic settings" are off (e.g., airflow sensor height is incorrect, distributor plunger height is incorrect). All this points to basic mixture setting which is controlled by the airflow sensor / fuel meter (plunger) relationship and is adjusted via the mixture adjust screw on the sensor arm. This setting does not have to be very far off spec to make the not start or run.
NOW THEN
Every time a fuel distributor is taken off the car and put back on (even if nothing was done to it), this mixture setting has to be re-adjusted. If a fuel distributor is removed and replaced with a new one, the new one must be adjusted. If a fuel distributor is removed and rebuilt, it must be reassembled and pre-set to a baseline adjustment setting then re-adjusted once on the car.
Does anyone see where this going, yet? 1) Check spark. 2) Check primary pressure. 3) Check that the fuel distributors are pre-set and adjusted correctly.
I will be absolutely stunned if this doesn't take care of it (assuming there is nothing else going on other than what you've stated thus far). And, I will give you 100 to 1 odds that the problem is related to basic settings on those distributors. If I'm right, you just saved a bunch of time and money. If I'm wrong (and it has been known to happen), what did you lose?
(Oh, and by the way, Brain is right you should consider finding a new tech).
|
Brian stewart (Eurocardoc)
Member
Username: Eurocardoc
Post Number: 334
Registered: 11-2001
| | Posted on Monday, June 24, 2002 - 8:27 pm: | |
if the cold control pressure is at 4.0 bar, it wont have enough gas for cold running. sounds as though the basics are not set correctly IMHO. needs a knowledgable tech. |
Dr. I. M. Ibrahim (Coachi)
Junior Member
Username: Coachi
Post Number: 53
Registered: 5-2002
| | Posted on Monday, June 24, 2002 - 8:56 am: | |
Larry, I got the car back because I did not think the mechanic knew what he was doing... and the car does not start cold or hot. It tries to start and dies immediately. It is as if it does not get any gas... |
Larry Fletcher (Fletch62)
New member
Username: Fletch62
Post Number: 2
Registered: 6-2002
| | Posted on Saturday, June 22, 2002 - 5:30 pm: | |
I spoke with Dr. I. M. Ibrahim's mechanic, he told me that he had a cold control pressure of 4 bar and that he did not check the control pressure when the car was warm. From the limited amount of information I was able to get it looked like that there was a problem with the control pressure and this would point to the warm up regulator. I am working on the tooling needed to start rebuilding warm up regulators. For any tech support or advice needed please contact me at any time.
Thank you
Larry Fletcher
CIS Flow Tech LLC |
Dr. I. M. Ibrahim (Coachi)
New member
Username: Coachi
Post Number: 49
Registered: 5-2002
| | Posted on Saturday, June 22, 2002 - 8:59 am: | |
I do not have any numbers, but the FD was rebuilt by Larry Fletcher email [email protected]. He rebuilt it because the mechanic said the plunger was stuck, gummed up; Mr. Fletcher is real congenial and helpful and he can give you the numbers. My car was running real rich on the right bank, and fuel was actually running out of the exhaust. I tried to start the car this morning, and it would not start. It tried, but could not stay firing. It is as if no fuel is coming into the combustion chambers...there is no smoke, nothing, it just tries to start, then dies. Where are the warmup regulators on the Boxer, do you know? Interestingly, the car started fine before the FD rebuild, but ran extremely rich due to the plunger being half open. Does this make any sense Ric and Brian.? |
Brian stewart (Eurocardoc)
Member
Username: Eurocardoc
Post Number: 331
Registered: 11-2001
| | Posted on Saturday, June 22, 2002 - 6:25 am: | |
The warm up regulators affect the "control pressure" to a degree , that is how the mixture is altered cold to hot. The system pressure is set by the bypass valve on the side of the FD head. If the system pressure is altered it will affect the control pressure but not vice versa. can you get some actual #s for us? Who "rebuilt" the FD head and why?
Brian |
Ric Rainbolt (Ricrain)
Junior Member
Username: Ricrain
Post Number: 155
Registered: 2-2002
| | Posted on Friday, June 21, 2002 - 3:07 pm: | |
On a Bosch "K" type fuel system, the warm up regulator(s) affect fuel pressure based on temperature, running time and engine vacuum. This affects "system pressure" in the fuel heads, and is inversely proportional to fuel delivery. Thus, the the warm up pressure regulators allow the system pressure to rise too quickly or too far, the delivery pressure drops too low and produces a lean mixture.
If the warm up regulators are out of whack, the car will run fine cold and terribly at temp, or vice-versa. The regulators can be "serviced", but it's a PITA (IMHO). Replacement regulators can be expensive (>$300/ea).
|
Dr. I. M. Ibrahim (Coachi)
New member
Username: Coachi
Post Number: 48
Registered: 5-2002
| | Posted on Friday, June 21, 2002 - 1:40 pm: | |
well, I had the FD rebuilt for the Boxer, and now the mechanic working on it says, it starts well, and runs fine, but as the engine warms up, it starts acting up... it runs lean and he says it won't start again till it cools again. Something about the pressure being too high. Why would that pressure be too high (fuel pressure that is)? Any ideas out there |
|