Golf mk5 2008 diesel cranks but won't start

And you will find it’s not a high pressure pump. It’s a circulation pump.

And you will find it’s not a high pressure pump. It’s a circulation pump.

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Depends on what you define as a HPP and it certainly isn't 1 BAR, as aforementioned, you didn't even know it was a pump & it's 7.5 BAR before bypass and to me that anything over 5 PSI & since I go back to carburetors, this is considered pretty high PSI.

And Vasco I think it’s unlikely to be the tandem pump. Although it has a test port on it to couple a gauge to if you have to.
I’ve never had to.
As before if the problem is fuel starvation as you suspect. You should investigate the function of the electrical pumps first.

Both pumps are powered I think from the same relay so they will run at the same time. So if you hear a pump humming when you activate them
It does not prove both pumps run. You have got to check. A pump that’s not spinning will restrict the flow from the other one.

And you will find it’s not a high pressure pump. It’s a circulation pump.

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You are extremely incorrect!

I feel I need to touch on this again & because if people dont understand basics WTF good is the information?

I would like to add that the PD fuel pump & driven by cam is not by definition a "circulation pump".

Any pump, regardless of amount of PSI generated & when it is to be used by another source to be expelled, injected or converted such as a fuel injector helix etc. is by definition an HPP regardless of returned to tank.

If the pump only circulated a fluid and returned it such as a water pump and without losing any fluid that is by definition a "circulation pump" whether open or closed systems too.

You will note that if you read the aforementioned SSP or RTFB it will not refer to the PD cam driven fuel pump as a "circulation pump" however, when observing the chiller for fuel cooler as example & which uses coolant, does use a "circulation pump".

You have as have others simply became too reliant on what you believe is a definition of HPP, this since what is in your face now and what isn't, you just dismiss others & dont understand how pump systems work or classified in general.

This is clear!

Hmm 1800 bar is extremely high, The high pressure side in direct petrol injection is I would consider very high. Normal working pressure for an electric fuel pump in a petrol or diesel vehicle though can be as high as 7.5 bar and that would normally considered the low pressure system. This tandem pump has a pressure relief valve that will come off it’s seat at 7.5 bar that does not mean the pump runs at that pressure. If you blocked the return pipe 7.5 bar max and no more. Mostly it will run about the same as the other low pressure pumps that are feeding it.

But you are perfectly correct you could consider any pressure above atmospheric to be high pressure.

And Vasco I think it’s unlikely to be the tandem pump. Although it has a test port on it to couple a gauge to if you have to.
I’ve never had to.
As before if the problem is fuel starvation as you suspect. You should investigate the function of the electrical pumps first.

Both pumps are powered I think from the same relay so they will run at the same time. So if you hear a pump humming when you activate them
It does not prove both pumps run. You have got to check. A pump that’s not spinning will restrict the flow from the other one.

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If reading the SSP you will see a great layout of how the system works and bypasses air.

Bleeding the system and testing actual output with gauges and volume measuring devices are the proper advisement using RTFB.

Verifying the engine will fire by aforementioned tests is also advised.

I read the SSP years ago when I learned that pd engine did not need a high pressure pump.

Agreed but if the op has not got all the test equipment we have got he can still do some basic testing with little more than a screw driver and some
Hose and a bucket. Hopefully a test light if required.

Anyway it’s a nice day here today. I guess it’s probably high pressure I’m going to open a bud and sit in the garden as we’re stuck at home.
Cheers

I read the SSP years ago when I learned that pd engine did not need a high pressure pump.

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But you forgot the pump even existed?

Look man, I'm just more concerned with people understanding basic operations versus splitting hairs on what you want to rename for actual function.

The pump in tank or on head driven by cam is by definition an HPP & regardless of stage it is at, that includes the helix in the injector pump itself.

Thank you all

What I did was:

1 - Disconnected the diesel hose that supplies fuel to the tandem pump.

2 - I used VCDS to purge and lots of fuel comes out.

3 - Now what?

4 - Disconnected the intact manifold and injected with starter fluid <-- Thanks Jack.

5 - I cranked and I was able to ear some explosions.

6 - "Good, good. Let the explosions flow through you".

7 - Injected more starter fluid.

8 - Cranked again and it is working like a Swiss clock.

9 - After like 15 minutes at idle I checked the fuel filter cup to make sure it was being filled by the pump at the tank. And it was full. So that fuel pump in the tank is working fine.

So, what makes sense is that I really ran out of fuel and had an air lock in the system.

The big issue is that I have to replace the fuel pump at the tank because it's there where the fuel sender sensor is.

Yay!

Jack,

In my opinion there are 3 types of high pressure diesel pumps:

- Mechanical diesel pump used on the first diesel vehicles.
- High pressure pump used on the common rail diesel vehicles.
- Unit injector (pump duse injector).

These three types of pumps produce pressures around 1500/2000 bar or even higher.

This TDI engine produces a pressure of 1900 bar per injector.

All others a low level pressure pumps that serves to pump fuel work with pressures like 5, 6 ,7, 8... bar. Not 1500 bar.

^ So this is why when read/ear high pressure pump it must be one of these 3 types of pumps.

Pinpointdiag shares my opinion.

Pinpointdiag said:

I read the SSP years ago when I learned that pd engine did not need a high pressure pump.

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Correct. PD engines have other 2 pumps one on the fuel tank and the tandem pump but none reaches the pressure to ignite diesel.

This high pressure is achieve at the unit injector which can rise the fuel pressure up to 2000 bar or even higher.

Correct. PD engines have other 2 pumps one on the fuel tank and the tandem pump but none reaches the pressure to ignite diesel.

This high pressure is achieve at the unit injector which can rise the fuel pressure up to 2000 bar or even higher.

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High pressure atomization is not a contingency of igniting diesel fuel for combustion in a CF engine!

I’v sat and thought for a wee while. If it’s worth continuing this debate as I’ve never been that fussed about getting that last word in, because there is more to life. But the basics of compression ignition are that the high pressure system has always been there to over come effectively the high combustion chamber pressure at the correct time and with the correct volume of fuel. The device that achieves this will require a suitable low pressure fuel supply.
Vasco, that’s brilliant that you have got your car going and I’m so sorry if I caused distraction. you are very diplomatic.
But it doesn’t really matter as jack says. about splitting hairs. He is correct that learning and information is king and I understand he
wants to help people learn rather than tell them what wrong.
So as he will always be here to help. Probably best to listen to him.

Take care everyone.

But the basics of compression ignition are that the high pressure system has always been there to over come effectively the high combustion chamber pressure at the correct time and with the correct volume of fuel.

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This is to respond to incorrect information, not to get the last word.

This statement is incorrect for 2 stroke or 4 stroke.

Lets focus on the 4 stroke principle & since that is what we play with here.

When fuel is sprayed in an intake path raw, it will operate a diesel engine ( example starting fluid, gas/diesel & or natural gas ) and is why an engine can runaway on it's own oil example, say if turbo leaks oil into intake and nothing is there to close the air inlet.

A four stroke compresses the fuel in a four or two stroke and ignites the fuel from heat of compression, the only thing high PSI atomization does is help it burn better.

In a four stroke it does this better when both valves are closed and at the correct time with high PSI it is not a contingency for combustion to take place.

Just read about how the diesel generator which ran away from underwater natural gas and blew up the oil platform in the Gulf.

Hi guys,

When the OP gets around to pulling the in-tank pump for the level sender repair he might try this after reassembling:

http://wiki.ross-tech.com/wiki/index.php/Fuel_Pump_Basic_Settings_for_PD,_PPD,_and_CR_TDI_Engines

Although it is necessary for CRs, most PDs with electric pumps support BS 035.

We already know this wasn't a timing problem but in the event you ever need to verify G40 is showing some data MVB 051 can be helpful in a PD:

051,1,Engine Speed,(G28),Specification (Idle): 770...870 RPM\nSpecification (Full Load): 2800...3200 RPM
051,2,Camshaft,Speed,Specification: Engine Speed/2 = ±50 RPM

Thanks Dana

I will read now about the gulf rig, was that the BP one. That sounds interesting. Most tech’s will have a memory of when a diesel runs off uncontrollably on its own lubricating oil while sitting on the ramp above you so you can’t even try to stall the thing. Try explaining that to the customer. A compression ignition engine will quite efficiently run on pulverised coal dust or anything else that will burn.

Vasco may have used diesel starting spray to get the vehicle to run but hair spray or air freshener would even have worked, only If needs must. Anything flammable it’s the control that’s the thing. Easy start is a brand name. But if I remember is Ether. And is almost too strong. Fine for starting an old cement mixer but a little to violent for a modern car. Every week at least one diesel arrives after being at another shop with that unmistakeable smell of easy start and a pile of replaced parts.