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If some dirt is trapped under the shim, rinsing it wont help - the spring pressure on the shim will hold the dirt in place. Try it, but I doubt it will help. IMHO I think it needs to be opened up.
jp 83 Euro S AT 57k
indeed it did not really help. I just got message from Kjet specialist from which I obtained my refurbished WUR.
He confirmed that the return flow is not correct. So I should have at least 1130cc / 30 secs (I only have 1 pump, otherwise it should be 1350)
If return flow is clogged, it would rather say that my control pressure would be much higher instead of too low, not?
Any idea where my return fuel flow could be clogged (I am measuring directly on the fuel return line over the engine cam) ?
Possible options :
1. fuel return line connected to outlet port on FD
2. outlet port on FD
3. inside my FD.. Is the system pressure relieve valve perhaps a possible culprit ? ( although my rest pressure 39 PSI after 1h and system pressure 84PSI are ok )
Perhaps the fuel pressure on this relieve valve is not sufficient to push it in so that excessive fuel can escape back to reservoir via the return line ?
If 24 ohms is correct resistance for heater, thats OK.
I would not adjust anything until you get the warm control rising as it should. If its faulty as fixed by somebody else, dont mess with any settings. If the problem is caused by a fault in the repair, good for you. If its caused by foreign matter (dirt, grit) getting in due to dirty fuel, they may charge you for a fix.
Important - tell them what the symptom/problem is, DONT try to tell them what you think the cause is ! Its their job to find out, and ask if they have tested it before you take it back.
jp 83 Euro S AT 57k
I might have found the problem when overthinking the KJET CIS working flow : pressure regulator valve stuck !
I am recalling to have overhauled the pressure regulator valve : new O-rings and 1 extra shim to raise the system pressure from 5.1 bar to 5.8 bar
Perhaps O-ring is stuck or dirt is causing it to become stuck.
I might have found the problem when overthinking the KJET CIS working flow : pressure regulator valve stuck !
I am recalling to have overhauled the pressure regulator valve : new O-rings and 1 extra shim to raise the system pressure from 5.1 bar to 5.8 bar
Perhaps O-ring is stuck or dirt is causing it to become stuck.
I'll check and come back to you.
That's what happened to mine. I mentioned it in post #3 here.
Well, I saw it but since your pressure was too high I did not gave it any attention since
my pressure was just the opposite
I removed the pressure regulator valve.
I did not seem to be stuck nor could I detect
any dirt.
I removed 1 shim , perhaps this would lower pressure on the spring
Car starts fine but I needed to adjust mixture
screw (turn CCW to lean) to raise idle from 600 to 1000 rpm.
But sparkplugs are still black and control pressure measuring at entrance of WUR
does not rise and stays at 1,8bar (25 PSI)
Next test to perform :
1. measure again the return flow
2. if return flow still too low, clean FD to make sure dirt is not clogging the FD
But there is one thing that is bothering me : the pressure measured at the entrance of the WUR.
Why is it not rising, supposing that my WUR is working fine ? Could clogged return line cause pressure drop @ WUR ?
Which root causes can drop the pressure @ WUR ?
That's what happened to mine. I mentioned it in post #3 here.
Can a clogged fuel return line lower the Warm Control Pressure measured at the WUR ? Normally clogged fuel line would rather increase the control pressure, not ?
My Control Pressure won't rise when engine warms up . It will stay @ 25 PSI => black spark plugs and engine runs rough
Nevertheless I have 12V @ WUR and WUR Bimetallic strip shows a resistance of 24 Ohm...
My WUR model ending -086 also has 24 Ohm heater, so yours should be OK. The diagram I saw recently is not quite correct - it doesnt show the groove with the critical Oring, or the Oring. If an incorrect section Oring was used this might lead to constant leakage leading to pressure loss. If it worked correctly for a while , then something has got inside it, OR the feed from the FD has a problem - is the input from the FD to the WUR at system pressure? Fit pressure guage, and close tap so you see system pressure.
jp 83 Euro S AT 57k
My WUR model ending -086 also has 24 Ohm heater, so yours should be OK. The diagram I saw recently is not quite correct - it doesnt show the groove with the critical Oring, or the Oring. If an incorrect section Oring was used this might lead to constant leakage leading to pressure loss. If it worked correctly for a while , then something has got inside it, OR the feed from the FD has a problem - is the input from the FD to the WUR at system pressure? Fit pressure guage, and close tap so you see system pressure.
jp 83 Euro S AT 57k
My WUR is also -086 model.
Feed from FD to WUR with closed tap shows me 5.8 bar (84 PSI)
So systems pressure is within range (5.2 - 5.8) and is still he same as it was before I had control pressure issues .
If system pressure is OK, does it also mean that my pump is providing the correct amount of pressure and flow ?
Black plugs are rich fouled. When you removed the shim from the pressure regulator I would have adjusted the idle screw to bring that up rather then the mixture screw. It's kind of difficult to adjust or know what the mixture is without a wideband AFR gauge and you have to rely on pressure readings and sound only, which isn't as accurate.
If your pressure out of the WUR isn't changing based on engine temperature, it sounds like the problem is in the WUR.
Black plugs are rich fouled. When you removed the shim from the pressure regulator I would have adjusted the idle screw to bring that up rather then the mixture screw. It's kind of difficult to adjust or know what the mixture is without a wideband AFR gauge and you have to rely on pressure readings and sound only, which isn't as accurate.
If your pressure out of the WUR isn't changing based on engine temperature, it sounds like the problem is in the WUR.
The control pressure at entrance of my WUR is about 1.2 bar (17 PSI) when cold (20° C) and after 1 minute running engine it rises
to 1,7 bar (25 PSI) and doesn't rise anymore.
So this would mean that my bimetal heater plate is working. But it sounds as if pressure from spring onto diafragma is not sufficiënt
Sounds like pump/filter and pressure regulator is OK. I still suspect the WUR internals.
jp 83 Euro S AT 57k
It indeed sounds more and more likely a WUR issue.
But what about the return flow? I still have only 480cc / 30 sec return fuel flow instead of 1130 cc ?
How is this related with my WUR?
Your flow IN test is misleading because the pump is not working against a pressure regulator. The flow OUT test shows how much fuel is flowing AFTER the pump produces the required pressure. Since the 475cc is ~ 30% of the spec, there is your problem - lack of power. Somewhere on the engine is a pipe with a blockage...
jp 83 Euro S AT 57k
Interesting test : without the spring inside the pressure regulator, my return flow = 1550 cc/ 30 secs
So nothing inside the FD, or return line is clogged.
I will try to remove the shim to see if I get the same result.
Interesting test : without the spring inside the pressure regulator, my return flow = 1550 cc/ 30 secs
So nothing inside the FD, or return line is clogged.
I will try to remove the shim to see if I get the same result.
Removing a shim won't help as this lowered my system pressure below 5.0 bar. (72 PSI)
So I reassembled everything as it was.
Then tried again : starting was good, running idle was also ok. ONLY pressure did not rise enough : ONLY 2.2bar (32PSI) warm control pressure!
Black plugs are rich fouled. When you removed the shim from the pressure regulator I would have adjusted the idle screw to bring that up rather then the mixture screw. It's kind of difficult to adjust or know what the mixture is without a wideband AFR gauge and you have to rely on pressure readings and sound only, which isn't as accurate.
If your pressure out of the WUR isn't changing based on engine temperature, it sounds like the problem is in the WUR.
Today I started car again to see how it reacted . Outside temp was 34°C / 93°F.
Starting was good but first 10 secs the idle was very slow rising from 400 to 1000 rpm. Pressure was 1.5 bar / 21 PSI .
After warming up for about 2 to 3 minutes, my pressure went to 2 bar / 29 PSI
So then I start driving the car, acceleration was good but once I kept accelerating above 60 Mph, it hesitated when I shifted up as if I lacked power
I checked my pressure again : still 2 bar. This is not good.
I also measured my mixture via color tune spark plug and it was nice blue when accelerating so combustion should be ok, not ?
I don't understand where my problem is, except that my pressure should be 3.4 bar instead of 2... so the only culprite that I can see is my WUR
07-17-2019, 07:09 PM
