TVR 350i ticking noise from pipe below cold start injector ?

[maston]

Hi all,

Just had a complete top end rebuild for my 350i.

Runs lovely, however, there is a "ticking noise" from the pipe below the cold start injector (the pipe that goes between the plenum and the fuel rail) and when you touch the pipe you can feel it vibrating (the ticking?).
Just wondered if anyone has come across this before and may not what it is causing it ???

For the record, we have not done a fresh oil/coolant change yet as we are doing that this wwekend.

Any help/advice greatly appreciated.

[Campbell]

Try disconnecting the cold start injector to see is the pipe stops pulsing, they are prone to sticking or weaping fuel.

Or it could be surging of fuel from the pump as the fuel rail is metal you proberly not feel it.

Cambelt

[maston]

Campbell said:

Try disconnecting the cold start injector to see is the pipe stops pulsing, they are prone to sticking or weaping fuel.

Or it could be surging of fuel from the pump as the fuel rail is metal you proberly not feel it.

Cambelt

Thank you for your reply.
So the pulsing I can feel is that actually fuel going from the fuel rail to the plenum or vice cersa ??? (apologies I am not a mechanic )
Also what does the pipe below the cold start injector actually do ?
And is it ok then to permanently disconnect the cold start injector ?
Thank you again everyone for all your help
Kind Regards
Ian

[350zwelgje]

Disconnecting (electrically) the cold start injector is 'standard' and will not cause problems.

The pipe below it, I think, is the fuel rail. Fuel is pumped from the back into this rail supplying all injectors, with one take-off for the cold start injector. Fuel then returns to the fuel pressure regulator (at the end of the rail in the engine bay) to ensure a certain fuel pressure in the rail. I would not expect any pulsing (firing of the injectors is I think to fast (milliseconds) to be able to feel that, but I could be wrong of course..), so it is good to investigate.

Could be that pulsing is happening due to a bottleneck in the fuel system like the fuel pump (you should be able to hear it running all the time when the engine is running) overcomes this bottleneck, a fuel line is 'squeezed' and the pump over comes the obstacle from time to time, faulty fuel pressure regulator (standard ones are not known to fail), fuel filter (inline or pre) that are of the wrong flow type or the fuel pump is on its way out or the electrical connections/relay are not ok....

Rob

[honestjohntoo]

maston said:

when you touch the pipe you can feel it vibrating (the ticking?)

I would suggest that the vibration is probably caused by a sudden change in pressure, and of the two places where that might happen, Pump and FPR, the pump non return valve may be failing at a certain pressure, releasing fuel backwards and then sealing again, without upsetting the engine performance,still seemingly OK.

If its the FPR then the malfunction may be similar step function pressure change as opposed to the normally smooth changes.

[maston]

Thank you all for your replies, appreciate it, will investiage further

Regards

Ian