Vaccum in diesel tank when cap removed?

Submitted: Friday, Jan 13, 2006 at 08:22
ThreadID: 29645 Views:1822 Replies:8 FollowUps:4
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When i pull up at a servo to fuel up and loosen the filler cap there is a vaccum in the diesel tank (Landcruiser HZJ 105). This can take maybe three seconds to stop sucking air in. My thoughts would be that there should be a one way breather somewhere and that this vaccum could starve the fuel pump or at least make it work harder. Has anyone any ideas on this one?

Mick
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Reply By: lindsay - Friday, Jan 13, 2006 at 08:30

Friday, Jan 13, 2006 at 08:30
Mick, be careful as i had a breather blocked on my way to the cape years ago and the vaccum sucked the sides of the steel tank in an cracked the sides and i lost fuel.
It was a series 3 landrover with a petrol motor ,i converted it to a perkins diesel and when i converted it i did not allow for a breather, as the petrol had a carbon canister which allowed the tank to breathe.
AnswerID: 148231

Reply By: Member - Duncs - Friday, Jan 13, 2006 at 09:06

Friday, Jan 13, 2006 at 09:06
I have noticed the Patrol do the same thing, perhaps not as bad as you indicate. I just had a look because I thought the cap had a breather but I can't find it.

Duncs
AnswerID: 148237

Follow Up By: sajiie - Friday, Jan 13, 2006 at 13:50

Friday, Jan 13, 2006 at 13:50
My patrol does it also but only when tank is almost empty. Same with sub tank.
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FollowupID: 401556

Reply By: Ron173 - Friday, Jan 13, 2006 at 09:09

Friday, Jan 13, 2006 at 09:09
Mick,

Sounds like a breather blocked for sure, usually routed from tank upwards to as high a point underneath as possible.

Sure you'd find it with a bit of a ferret around underneath or ramp if available, I'd do it sooner rather than later if it was me though, or you will get problems.

(prob take a grease monkey 10 mins, if hes not trying to rip you off)

Ron
AnswerID: 148239

Reply By: Alex H - Friday, Jan 13, 2006 at 10:17

Friday, Jan 13, 2006 at 10:17
My dad had the same problem on a car he had about 20 years ago. He solved it by drilling 2 1mm holes in the filler cap - one thru the outer hard cap, the other thru the rubber seal, offset by about 5mm to slow fuel evaporation in hot weather.
Probably better to fix the breather, but I thought I'd mention it anyway.
Cheers,
Alex
AnswerID: 148256

Reply By: cokeaddict - Friday, Jan 13, 2006 at 13:56

Friday, Jan 13, 2006 at 13:56
To the best of my knowledge, they are supposed to be like that. I was told that its designed that way so that it stops excessive condensation in the tank. Also was told that if when you loosen your cap, if you hear the suction, its a good indicator that all your hoses are tight and without leaks, for example.... if when you loosened your cap, you didnt hear the suction, chances are ... you have a loose hose clamp in your fuel line OR a pinhole somewhere in the feed line.

Both my GQ's did it and i have heard many do the same when filling up at a servo.
Ange
AnswerID: 148301

Follow Up By: cokeaddict - Friday, Jan 13, 2006 at 13:57

Friday, Jan 13, 2006 at 13:57
Oh hello Mick.....sorry didnt realise it was you.

Hope ur all well...tc
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FollowupID: 401559

Follow Up By: fatz - Friday, Jan 13, 2006 at 14:01

Friday, Jan 13, 2006 at 14:01
Goin good Ange, we'll have to catch up soon. Looking at a trip to Jenolan at some stage in early March if you're keen.

Mick
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Reply By: fatz - Friday, Jan 13, 2006 at 14:03

Friday, Jan 13, 2006 at 14:03
Thanks Guys, I might get under it and have a search around. My thoughts would be that it would have a breather somewhere with a one way valve to stop fuel leaking out but would also have a filter to stop it sucking dust and moisture in.

Mick
AnswerID: 148304

Reply By: greenant - Friday, Jan 13, 2006 at 14:21

Friday, Jan 13, 2006 at 14:21
I have a HJ60 and the breather is behind the rear drivers side panel and comes off the filler pipe just below where the pipe goes to the actual filler before the tank itself hope this helps

Greenant
AnswerID: 148310

Reply By: Steve - Saturday, Jan 14, 2006 at 00:05

Saturday, Jan 14, 2006 at 00:05
When i pull up at a pisstop with my donkey, it has a bleep and it farts ...for about three seconds ...My thoughts would be that there should be a one way breather somewhere ...Has anyone any ideas on this one?
AnswerID: 148463

Follow Up By: fatz - Monday, Jan 16, 2006 at 15:18

Monday, Jan 16, 2006 at 15:18
Yep, stick your head up the donkey's ^$$ and keep breathing in...It may not help you but it will certainly help the rest of the decent and helpful folk on here.
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FollowupID: 402105

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