K-Jetronic Problem
07-18-2002, 07:49 PM
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K-Jetronic Problem
I have a 1982 928 Euro 4664cc with K-Jetronic.
SOme idiot pout half a kilo of sugar in the tank and since then I have cleaned the system, reconditioned then Fuel Distributor, all new injectors and lines, cold start valve works, its was soaked and cleaned as were other parts. I have a problem with control pressure. The car starts and runs but very soon after gets hot and runs lean. If I switch off ignition for even 2 seconds and restart it pulls well again for another 30 seconds or so. WUR is clean, all fuel lines and vacuum lines are new and OK, is the WUR pressure adjustable? as the inlet has high pressure and the return side doesnt have a great volume or pressure of fuel to the return. Its not blocked but the pressure builds very quickly. the Fuel Distributor was professionally rebuilt and tested OK on their jig.
Any help appreciated <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
SOme idiot pout half a kilo of sugar in the tank and since then I have cleaned the system, reconditioned then Fuel Distributor, all new injectors and lines, cold start valve works, its was soaked and cleaned as were other parts. I have a problem with control pressure. The car starts and runs but very soon after gets hot and runs lean. If I switch off ignition for even 2 seconds and restart it pulls well again for another 30 seconds or so. WUR is clean, all fuel lines and vacuum lines are new and OK, is the WUR pressure adjustable? as the inlet has high pressure and the return side doesnt have a great volume or pressure of fuel to the return. Its not blocked but the pressure builds very quickly. the Fuel Distributor was professionally rebuilt and tested OK on their jig.
Any help appreciated <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
07-18-2002, 07:52 PM
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One thing I forgot to mention, the car ticks over well at 800rpm and will freely rev to 6000rpm smoothly , the problem only appears under load when driving.
07-19-2002, 12:52 AM
#4
Jackin,
One other question. Did they reset the fuel mixture when the system was rebuilt? Your system may be acting normally in that it is supposed to start rich when cold and lean up when the engine temp rises and the heater in the WUR kicks in. Also, when they rebuit the distributor, did they adjust the number of shims in the relief valve to get the correct control pressure? Sorry I didn't think of these sooner.
Dennis
One other question. Did they reset the fuel mixture when the system was rebuilt? Your system may be acting normally in that it is supposed to start rich when cold and lean up when the engine temp rises and the heater in the WUR kicks in. Also, when they rebuit the distributor, did they adjust the number of shims in the relief valve to get the correct control pressure? Sorry I didn't think of these sooner.
Dennis
07-19-2002, 10:47 AM
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Jack,
You need to test the control pressure running. Get a copy of Ben Watson 'How to Tune and Modify Bosch Fuel Injection' from Amazon, and a gauge set from JC Whitney. Mine has just gone high again, 3 weeks after fixing it the first time. Blockage in the WUR, under the inlet metal gauze filter. Washed in carb cleaner, blown out with air. Symptoms same - revs ok no load, but acceleration and throttle response tapering off. Control was at 70psi (with system at 75psi, no much room to move), should be 40-45psi. Also check the return pipe, blow it out.
jp
You need to test the control pressure running. Get a copy of Ben Watson 'How to Tune and Modify Bosch Fuel Injection' from Amazon, and a gauge set from JC Whitney. Mine has just gone high again, 3 weeks after fixing it the first time. Blockage in the WUR, under the inlet metal gauze filter. Washed in carb cleaner, blown out with air. Symptoms same - revs ok no load, but acceleration and throttle response tapering off. Control was at 70psi (with system at 75psi, no much room to move), should be 40-45psi. Also check the return pipe, blow it out.
jp
07-19-2002, 05:17 PM
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When I remove the fuel return line and place this into a tank there is a smooth and regular flow of fuel, its doesnt surge or increase the flow when the car is revved up.
I am sure the return line is fine as there is a reasonable flow of fuel that is not under pressure.
Does anyone know the amount of fuel that is expected on the return line? <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
I am sure the return line is fine as there is a reasonable flow of fuel that is not under pressure.
Does anyone know the amount of fuel that is expected on the return line? <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
