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Discussion Starter #1
Hi everybody.

Hope I don't sound like an idiot whilst trying to make sense of the problem I have. I'm just repeating what my mechanic has told me. I have limited knowledge of engines.

My ix35 2litre premium 4WD 61 plate, broke down 4 weeks ago. I had it towed to the nearest garage, everything pointed to a fuel issue as it stuttered, stalled, then a mile down the road started juddering and stopped.
No engine management lights. It would crank but not start.

The garage initially changed the fuel filter, but it didn't help. They then sent the high pressure pump to be tested by a bosch specialist whom said its working fine.
We've now had advanced bosch diagnostics run and can only pick up the code P0253. The code is permanently on, no need to crank the engine, it can't be cleared.

There's plenty of fuel going into the pump, the pump is turning but zero or very very little coming out. They've ran voltage tests and looked at rail pressure modulation for the rail sensor. They say it looks fine. They've also tested continuity on just about every wire in the car, and all seem fine.
They think the problem is still with the pump despite being tested and given the all clear.

They're also unsure whether the ECU has stored this fault and is now causing the problem.

Has anyone got any feedback or advice they can give? I can feed back to the garage and perhaps get some exact replies.

The car twice stuttered over a two week period whilst pulling out of a junction on a hill (it'd lose power for a sec and then judder and accelerate fine). I only had the car a month before this all started.

Thanks for reading this far I appreciate any response!

Ben
 

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The trouble code relates to the Inlet Metering Valve (IMV) on the high pressure fuel pump. The IMV is a solenoid valve that controls how much fuel is allowed to enter the pump. If the valve is fully closed no fuel will enter the pump, and no low pressure fuel in means no high pressure fuel out.

The IMV is controlled by the engine ECU using a duty cycle signal. The higher the duty cycle that is applied to the solenoid the lower the fuel delivery to the pump will be. So the first thing to try is simply disconnect the solenoid's harness connector, which in effect applies a zero duty cycle which should fully open the valve allowing maximum fuel to enter the pump. And max fuel in means max fuel out. See if that at least gets it started.
445490
 

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Discussion Starter #3
Thanks for the quick reply @AUTOSPARK .

Just had this back from my mechanic:

The "ITV" is new.Checked live and earth to it and scoped the duty cycle,all ok.Identified HP pump getting fuel as we have fuel returning from the pump leak back of the pump.????Code will not clear so suggesting electrical fault. Physical checks suggest pump???

Any feedback would be greatly appreciated.

Thanks again
Ben
 

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Did they try disconnecting the valve to see if the engine would start?
They say they checked the valve's control signal. What was the duty cycle value they measured?
 

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Discussion Starter #5
Thanks autospark.
We disconnected the valve today, we could here it switching on and off whilst reconnecting.

When we wiggled the wiring loom we noticed the valve was opening and closing. So we opened the loom up to try and find the short/problem. But it disappeared. Funnily enough the code has now disappeared as well...

But the car still won't start, with the common rail registering no pressure. I'll try and find out the duty cycle.

My mechanic is worried the afformentioned code is something historic and isn't the reason the car broke down, also that the car should still be running but in limp mode.

They couldn't prime the high pressure pump because the code needed to be cleared first (which until now wouldn't clear) , so they pulled fuel through the line with a vaccume to prime it. They will do a bleed diagnostic and prime on Monday but aren't hopeful it'll make a difference as they already got fuel to the pump.

They say everything points to a broken pump despite it being given the all clear on the bosch rig. It's also had a new suction control valve whilst it was being tested.

They've worked really hard on the car but are trying to avoid replacing the pump (at such a high cost) when it's been given the all clear. But can't think of what else it could be.

It's driving me crazy.

I trust and know the mechanics.

Thanks again.
 

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They've worked really hard on the car but are trying to avoid replacing the pump (at such a high cost) when it's been given the all clear. But can't think of what else it could be.
If we assume the pump is working properly but there is no pressure building in the common rail that can only mean that the fuel is leaking out of the rail faster than the pump can deliver it. That is actually quite a common cause of non starts on CRDi engines. More often than not the leak is via a faulty injector. Has an injector leak off test been carried out?
 

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Discussion Starter #7
They're going to do a leak off test today.
They sent me this as a reply to your message:

Possible, but not likely as we have no diesel getting to the injectors or signs of diesel flooding into the combustion chamber ie white smoke from exhaust or hydraulic lock.
Spoken to the guys who ran the pump through their rig and they say its very unlikely the pump is knackered if they've tested and said its fine.

Is there perhaps a sensor that could be stopping the pump from running?

They are going to do a bleed and prime diagnostics on the system today now the previous code has been cleared.
They're also going to do a leak off test just to make sure. As they're both quick and easy to do.

Still no closer to figuring it out... 😩

Thanks again.
 

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They're going to do a leak off test today.
They sent me this as a reply to your message:



Spoken to the guys who ran the pump through their rig and they say its very unlikely the pump is knackered if they've tested and said its fine.

Is there perhaps a sensor that could be stopping the pump from running?

They are going to do a bleed and prime diagnostics on the system today now the previous code has been cleared.
They're also going to do a leak off test just to make sure. As they're both quick and easy to do.

Still no closer to figuring it out... 😩

Thanks again.
I think Sparky alluded to this in post #2 with the inlet metering valve which the ECU controls. But if they tested the pump one would assume that valve is integral and also would have been bench run as part of the test
 

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That's inside the pump I think. I'm not really great on Diesels myself just reading up on the code and what's been written. Handy to know what model it was for the right manual
 

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What's interesting is it suggests it fuel limits to limp mode on this code but this is not running at all.
 

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Discussion Starter #17
This is the bit (IMV) that has been replaced (attached).

When the harness was taken off the IMV/suction control valve, the engine still wouldn't start.
 

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ok, was not aware it was also called that, but Hyundai calls it the fuel pressure control valve or P-PRV
 

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From what I've read 100bar is about the default pressure with the connector off for that regulator.
 

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Discussion Starter #20
OK thanks very much. I'm forwarding details on to my mechanic as and when.

Just waiting for them to get back to me about doing the leak off test and bleed and prime.....


Appreciate the help.
 
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