On 2/10/2025 at 4:28 PM, nicam49 said:

I had this on a Renault Scenic diesel, had to get towed to the main dealer, 'cos AA couldn't fix it. Turned out the egr needed cleaning. 

Diesel engine,  I agree EGR blocked or jammed. This remains closed until engine reaches working temperature. 

Fuel filter 2 weeks old.  Priming pump and fuel hoses same time.  Only pipes not changed are the from fuel tank and return pipe. Injector leak off pipes changed 5 months ago. It seems like its sucking in air through the fuel filter. Priming doesn't seem yo be removing the air bubbles.

Yes it was the egr valve that was causing the problems with no power and no revs the bottom of the valve haD come clean off. So no faults showing as it was still moving rod. But not closing the gap causing the problems. But now I think I'm getting  air in the fuel line. 

the fuel filter was new and just replaced.  When priming the fuel system with pump im still getting small stream of bubbles. Do I have to run the engine and prime bulb  is there anyway to remove the air from the fuel lines. Or is it normal to have small bubbles in line when primer pump is pressed. This problem wasn't there before I changed the filter and priming pump pipes. So really don't think its a sensor and feel more like its air in system still. As I had it running normal for 1 day to work but then went into limp mode the next day. And again had it running normal on the road for 10 min hard drive.  Then when tried later in day limp modecand fuel issue again. 

If the new primer and pipes were low quality they could be adding air to the system.  It only takes a tiny pinhole or hairline to allow air in, but you'll never see any diesel leak out.

You said:

 "This problem wasn't there before I changed the filter and priming pump pipes." 

Is this one of those situations where the filter housing gasket has been fitted back in the wrong place... 🤔

I don't know the type of filter it uses... If it's one that goes inside a housing then it has a sealing ring/gasket that often gets fitted ABOVE the filter seating, instead of BELOW it. Causes all sorts of problems to do with air ingress. 

Its a sealed unit. Thought it could be a fake china ebay filter so refitted the old one still the same problem

 

On 5/1/2025 at 10:38 AM, TomsFocus said:

If the new primer and pipes were low quality they could be adding air to the system.  It only takes a tiny pinhole or hairline to allow air in, but you'll never see any diesel leak out.

I've now ordered  a new pipe and primer pump so will fit these incase of bad fitment.  Thank you.