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Discussion Starter · #1 ·
Hi,
I've replaced the high pressure pump and injectors on my 2011 Tucson/ix35 2.0L diesel.
While priming the low pressure side was fairly straight forward it appears that cranking the engine over does not deliver diesel to the common rail and injectors.
I suspect that the suction control valve is being kept closed by the ECU and blocking fuel to the rail.
Apparently there is a priming function that is run via the GDS software but since I don't have the interface for the car I'm a bit hamstrung there.
Are there other methods of priming the high side. I thought of disconnecting the electrical connection to the SCV and opening it directly from a 12V battery source (its only a solenoid after all)while cranking the engine.
Has anyone else got any suggestions.
cheers Pete
 

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I've not done any work on that particular engine but generally applying 12V across the SCV/IMV fully closes the valve. If you want to force the valve fully open simply unplug it's harness connector.

To prime the pump I'd suggest disconnecting the fuel return hose and connect a vacuum pump to the side that leads to the pump/injectors. Use vacuum on the return line to suck fuel through the pump. Once you have fuel coming through, pinch the hose to prevent air leaking in then reconnect the hose leading back to the tank. Hopefully that will get it started.

Scottie.
 

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Discussion Starter · #3 ·
Autospark,


Thanks for your reply. I think you are correct in that applying 12V to the SCV will close it. My OBD11 scanner arrived and after reviewing the codes and the GDS manual there was a reference to full current across the SCV closes the valve. I will disconnect the lead and see if I can get some fuel into the rail.
In regard to priming the pump. I connected a battery source through a switch directly to the electric fuel pump in the tank. I pumped fuel through the filter into the high pressure pump inlet and could see the air come out the return via a plastic tube into a bucket. I then disconnected the tube and re connected the return line to the tank. I've also taken out the SCV a couple of times and can see residual fuel sitting in the recess. So I seem to have fuel to this point on the high pressure side.
I've unscrewed the pressure sensor at the end of the rail and it was completely empty so I definitely have no fuel getting up to the rail.
Any further suggestions are welcome but I will definitely try disconnecting the lead to the SCV and turn it over. cheers Pete
 

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Question: Does spraying starter fluid into the air intake (on a diesel engine) actually work to start the engine?

Have heard that some could start their diesel engine by using starter fluid??

Sorry for the side track
 

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I connected a battery source through a switch directly to the electric fuel pump in the tank. I pumped fuel through the filter into the high pressure pump inlet and could see the air come out the return via a plastic tube into a bucket.
You shouldn't have too much trouble priming the pump if there is an electric lift pump in the system. Some diesels don't have an electric pump and those can be a real pain to get started once the fuel system has been opened.

You mention reviewing codes. What are they?
Have you checked the fuel pressure on the scan tool during crank. Is there any pressure building in the rail?
What was the original reason for replacing the pump & injectors?

avisitor said:
Question: Does spraying starter fluid into the air intake (on a diesel engine) actually work to start the engine?
That depends on what is causing the engine not to start in the first place. If it's not starting because there's a fuel delivery issue, then yes it will start on starting fluid since that is a fuel source.
 

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I connected a battery source through a switch directly to the electric fuel pump in the tank. I pumped fuel through the filter into the high pressure pump inlet and could see the air come out the return via a plastic tube into a bucket.
You shouldn't have too much trouble priming the pump if there is an electric lift pump in the system. Some diesels don't have one and those can be a real pain to get started again after the fuel system has been opened.

You mention reviewing codes. What codes are being logged?
Have you checked fuel pressure during crank with your scan tool? Is there pressure building in the rail?
What was the original reason for the pump & injector replacement?

avisitor said:
Question: Does spraying starter fluid into the air intake (on a diesel engine) actually work to start the engine?
I suppose that depends on why the engine isn't starting in the first place. If the non start is due to a fuel delivery issue, then yes it should start on the starting fluid since it's a fuel source. It should start but wont necessarily continue to run.
 

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Discussion Starter · #7 ·
Autospark,


I've replaced the high pressure fuel pump and injectors after the original pump let go and put metal through the fuel system.
I only just received the code reader so haven't had a chance to monitor fuel pressure. The codes that are up could be a bit spurious as I've had the battery on and off numerous times.
The plan at the moment is to connect the code reader to monitor fuel pressure, disconnect the lead to the SCV so the valve is open as per previous discussion and crank the engine.
Do you know how long it should take for the fuel to work it's way up, is it instantaneous. How does the air escape from the rail ?. The system does have a pressure regulating valve on the other end of the rail which leads back to the tank via a banjo and I guess air would escape through the injectors and out of the exhaust valve port.
I thought about pre flooding the rail with diesel so the initial fuel inrush is not so great but this is difficult as I have to disconnect the system again. I could try to put it in by disconnecting the pressure sensor but not sure if this is at all necessary.
cheers Pete
 

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Yes, pressure should build in the rail pretty much instantaneously because the injectors wont start to inject the fuel into the cylinders until a specific rail pressure has been achieved. I've attached an oscilloscope trace of the rail pressure sensor voltage from a 1.7 CRDi engine (Kia Sportage). The dashed vertical lines on the trace measure the time interval between the start of engine crank and the rail pressure being high enough for the injectors to start operating....about 1.5 seconds in this case.

Monitor the rail pressure sensor voltage on your scan tool data list (or just use a voltmeter if there isn't a data pid for it in your tool). It should be 0.5V when the ignition is on and it needs to reach 1V during crank before the PCM will start firing the injectors. If 1V isn't achieved the engine won't fire.

SCOPE TRACE OF RAIL PRESSURE SENSOR VOLTAGE DURING ENGINE START.
 

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