CIS K-JET Cold Start Issue
#31
Jon,
The later Mercedes did run without accumulators. Actually, all CIS with O2 sensors have frequency valves which dampen any pressure fluccuations better than the accumulator. Concerning the accumulator holding pressure, since it's capacity is less than 75 ml, that function is best left to the check valve at the pump and the relief valve on the distributor. Actually, considering that they are prone to leak with age, the accumulators are more of a liability than an asset.
Dennis
The later Mercedes did run without accumulators. Actually, all CIS with O2 sensors have frequency valves which dampen any pressure fluccuations better than the accumulator. Concerning the accumulator holding pressure, since it's capacity is less than 75 ml, that function is best left to the check valve at the pump and the relief valve on the distributor. Actually, considering that they are prone to leak with age, the accumulators are more of a liability than an asset.
Dennis
#32
Update 5/29/07
Ok. To continue the saga...
I have not received the gauges yet but I have visually confirmed that the accumulator is not leaking or seaping fluid externally. It appears to be completely dry.
I have also confirmed that by pressing on the gas pedal fully, after three igntiion starts with a cold engine, it will kick over rather consistenly.
It also runs great right away, no stumbling.
So are we starting to lean toward cold start, or can the fuel accumulator leak internally?
I have not received the gauges yet but I have visually confirmed that the accumulator is not leaking or seaping fluid externally. It appears to be completely dry.
I have also confirmed that by pressing on the gas pedal fully, after three igntiion starts with a cold engine, it will kick over rather consistenly.
It also runs great right away, no stumbling.
So are we starting to lean toward cold start, or can the fuel accumulator leak internally?
#33
Brad,
From your description of the problem so far, it doesn't really sound like an accumulator problem to me. However, you can verify the leakdown after your gauge and book arrive. The first thing I would check would be the cold start injector. It is relatively easy to access. Also, a malfunction here would fit the description of your problem. The control pressure regulator (WUR) is also a possible cause. It is a simple procedure to check it with the gauge.
To answer your question on the accumulator: There are two types of accumulators used on the early cars. One type has a third hose connection that is a leakage line that directs leakage back to the tank. This type would not neccessarily show any external signs of leakage.The other type simply vents the back side to the diaphram to atmosphere, so a significant leak would show up after running the car for awhile.
From your description of the problem so far, it doesn't really sound like an accumulator problem to me. However, you can verify the leakdown after your gauge and book arrive. The first thing I would check would be the cold start injector. It is relatively easy to access. Also, a malfunction here would fit the description of your problem. The control pressure regulator (WUR) is also a possible cause. It is a simple procedure to check it with the gauge.
To answer your question on the accumulator: There are two types of accumulators used on the early cars. One type has a third hose connection that is a leakage line that directs leakage back to the tank. This type would not neccessarily show any external signs of leakage.The other type simply vents the back side to the diaphram to atmosphere, so a significant leak would show up after running the car for awhile.
#34
My 83 accumulator had NO vent, just a hole at the top plugged with a screw. On removal the screw was wet with fuel, indicating diaphragm failure....replacement cured the warm start problem for me, but YMMV.
jp 83 Euro S AT 50k
jp 83 Euro S AT 50k
#35
Update:
Dumb Question Alert!
Just to be clear, the thermotine (coolant Sensort) switch sits right behind the WUR on the waterbridge. Correct?
If this is correct , I am getting nada!
Please confirm!!!
Just to be clear, the thermotine (coolant Sensort) switch sits right behind the WUR on the waterbridge. Correct?
If this is correct , I am getting nada!
Please confirm!!!
#36
That sounds right. It's located directly under the WUR. Is there no evidence of it switching? IIRC, you have to make sure your test leads are connected right on the first try, otherwise you will have to wait for the switch to cool off again before testing.
#37
Brad, What does 'nada at the thermotime' mean ? Ignition on, one lead should have 12V on it, and when cold, IIRC, it should come out and go to the cold start injector. If this is the three wire , testing is a bit more complicated. DO a search on posts on this by Wally P, I have been here before myself when looking for a similar problem.
jp 83 Euro S AT 50k
jp 83 Euro S AT 50k
#38
Brad,
The sensor on the top of the bridge, behind the WUR, is the sender for the temp gauge on the dash (wrong thing to check). The thermo-time switch is located on the front, passanger side of the bridge, tucked in by the coolant hoses. You will notice one of the square bosch connectors plugged onto it.
The sensor on the top of the bridge, behind the WUR, is the sender for the temp gauge on the dash (wrong thing to check). The thermo-time switch is located on the front, passanger side of the bridge, tucked in by the coolant hoses. You will notice one of the square bosch connectors plugged onto it.
#39
A test light can be used for initial test on the thermotime switch. When cold the test light should show a circuit between the two posts (connector removed). If that shows a circuit then check each post to ground. If either shows a crcuit to ground or no circuit between the two posts the switch is bad.
Dennis
Dennis
#42
Ok. Quick update:
The good: Switch is operating fine. I tested per Dennis' instructions and everything checks out.
The bad: The electrical connector that goes over the switch is NOT showing any resistance as like the other connectors are. So now what? Fuse? Crack in the wiring harness? Any alternatives?
The good: Switch is operating fine. I tested per Dennis' instructions and everything checks out.
The bad: The electrical connector that goes over the switch is NOT showing any resistance as like the other connectors are. So now what? Fuse? Crack in the wiring harness? Any alternatives?
#44
Sounds right to me. Here is where I would use a networking type cable tracer - isolate which wire at the switch should have +12V on it, inject a tracing tone on it, and follow the tone with the tracer sensor until it stops somewhere it shouldnt, or it reaches the fuseboard, and there is a problem there. Its a real PITA trying to test this sort of thing with a DVM and long bits of wire all over the car...DIsconnect battery earth please.
jp 83 Euro S AT 50k
jp 83 Euro S AT 50k
#45
Originally Posted by checkmate1996
The bad: The electrical connector that goes over the switch is NOT showing any resistance as like the other connectors are. So now what? Fuse? Crack in the wiring harness? Any alternatives?