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Air in diesel cure !

Posted: Tue Jul 06, 2010 1:22 pm
by gumby6371
Hi all I seem to have cured the problem I had with fuel leaking back when she's parked up leaving me primimg her most mornings.

I've tried changing the spill pipes and various other bits of tubing, cleaned and reseated the fuel filter housing and even checked the lifter pump etc.....

I mentioned it to a mechanic friend of mine and he just scratched his head and said he'd have a think about it.

Well he turned up at my house last night, popped the bonnet, cut the fuel pipe just before the filter housing and slapped a little non return valve in.

Got in this morning after the car had stood for 12 hours and YES!!! THERE IS A GOD !!! started first turn of the key.
there was a couple of seconds of splutter as the pressure built up along the path back to the tank but she ran, hopefully never to need priming again (he said knowing he was on to a loser)

So there you go, when all else fails, BODGE IT !!!!

Hope this helps anyone with a similar problem, not sure how much the valves are but I'm guessing pennies as all my mate wanted was a pint next time I was in the pub.

Re: Air in diesel cure !

Posted: Tue Jul 06, 2010 2:16 pm
by swiss
You know, I had the same issue a couple of years back and went through most all the same troubleshooting steps. I did indeed end up buying a wee check valve but by the time I got off my arse to install if the problem somehow cured itself. Paid about three squids for the valve from Diesel Bob's website.

Re: Air in diesel cure !

Posted: Tue Jul 06, 2010 3:00 pm
by Welly
I thought that diesel must return to the tank via the spill lines - I hope he hasn't stopped it doing this as it'll build up pressure in the fuel pump won't it?

Re: Air in diesel cure !

Posted: Tue Jul 06, 2010 3:27 pm
by omega
Welly wrote:I thought that diesel must return to the tank via the spill lines - I hope he hasn't stopped it doing this as it'll build up pressure in the fuel pump won't it?

this is done quite often but its fitted in the fuel line from the tank to pump and not the return.

Re: Air in diesel cure !

Posted: Tue Jul 06, 2010 5:57 pm
by sirwiggum
As I've mentioned a few times, my fuel filter housing is the rarer 190162 2 port Siemens.

Last owner had put a 3 port Siemens on and blocked off the 3rd port.

Eventually air was getting in this.

Solved by getting a new 190162 from Pug (about £60). Another spare one from the scrap yard afterwards, put the clean filter from the 3 port in so ready for next fuel filter change, swap the housings! :)

Re: Air in diesel cure !

Posted: Wed Jul 07, 2010 12:15 pm
by gumby6371
The non return is fitted between the pump and the fuel filter, unburnt fuel returns to the pump from the spill pipes direct, so it shouldn't effect any build up of pressure. If the fuel pump goes bang I'll eat my words and let you all know :cheesy:

Re: Air in diesel cure !

Posted: Wed Jul 07, 2010 2:06 pm
by swiss
No no, IIRC the return line is quite separate.

Re: Air in diesel cure !

Posted: Wed Jul 07, 2010 3:02 pm
by steve_earwig
No no no, it dumps it out on the road :roll:

Re: Air in diesel cure !

Posted: Wed Jul 07, 2010 3:11 pm
by swiss
Cool, that'll upset the ecomentalists ^_^

Re: Air in diesel cure !

Posted: Wed Jul 07, 2010 3:14 pm
by Welly
When you lift your foot off the gas a valve should open on the fuel rail to send the excess fuel back to the tank non?

Shirley it can't be returned to the pump because the pump's job is to pressurise the fuel to the injectors/rail.

Re: Air in diesel cure !

Posted: Wed Jul 07, 2010 4:01 pm
by swiss
Yes, but it doesn't go back down the same line the fuel uses to reach the pump in the first place. Therefore the returned fuel will not encounter the the check valve. The check valve should, in theory, simply maintain fuel pressure up to the pump.

Of course if the air leak is before the valve, all the fuel up to that point is still liable to drain. Perhaps therefore a check valve should go as near the tank pick up as possible, so as to keep any fuel between the tank and the pump where it is? I can't remember if it's pipes or hoses at that point.