Fuel pump cavitation caused by petrol heater t-piece feed?

[mshaw1980]

Oldiebutgoodie may be able to help with this one...and maybe a few other of you

I have my webasto petrol heater fuel line spliced into the fuel tank outlet hose before it reaches the van's electric fuel pump. The problem I am having is my fuel pump after about three or four months starts to get a bit 'sticky' in that it wont prime when you turn the ignition on. If I give it a tap then it will then prime when turning the ignition on again which tells me its starting to fail again. When the pump is running it never sounds smooth. There is always like an intermittent buzzing coming from it.

I am starting to wonder if the webasto fuel feed line is the reason for this as I am thinking that the van fuel pump is sucking the fuel out of it leaving behind a vacuum or air, causing pump cavitation.

Does thay sound feasible? Where do you peeps take your petrol heater feed from?

Cheers

[slowcoach]

Mine comes from the same point, just after the tank.

Is the pump earth good and clean?

[mshaw1980]

Have wired the earth direct to the battery negative now as it was an issue previously when negative was connected to the chassis

[slowcoach]

Do you have the T outlet to the heater dropping at a down angle, so fuel 'drops' out the main line to heater? any air is meant to stay in the main fuel line as per install manual. other than that not sure! only had mine installed for a month or so but the fuel pump hasnt changed its tune..

[Oldiebut goodie]

The tee-piece will not cause a problem to the pump. The pump cannot suck fuel from the heater line as when the heater pump is switched off it acts as a stop valve. It sounds like your van pump is failing if a tap will get it working again.

[mshaw1980]

Yes I realise that my van pump is failing but this will be the fifth one in about 3 years now. My question is why? I have a fuel injection tank from brickwerks, a bosch fuel pump, pump in same place as everyone else and apparently heater fuel line is in the right place.What is going on?
Could I have a vacuum in the tank causing pump to work harder?

[slowcoach]

Fuel pressure regulator failing? Have you been able to measure the pressure with a gauge attached to the fuel loop? That Could be worth a check. Injection pumps aren't cheap hey. A small fuel pressure gauge is cheap and a length of fuel hose make a quick diagnostic tool. I've had one from when I had the wbx and had issues there.