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 Fuel pipe fright
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EdinburghJoe
V4 Fan

United Kingdom
127 Posts

Posted - 09 Sep 2021 :  12:58:21 Show Profile Reply with Quote
Hi all,
I just had my worst driving experience with my v4 - it shook me up quite a bit. I was stuck in traffic, noticed an increasingly powerful smell of fuel, couldn't pull over to check it out. Eventually cleared the traffic, and then the engine died.

Turned out the fuel hose had come entirely disconnected from the in-line filter between the pump and the carb - must have spewed quite a lot of fuel- the driver behind pulled over with me and said she noticed fluid spilling out and thought I had a radiator leak. I can't believe how lucky I must have been to avoid a fire - the fuel was all over the exhaust downpipe, must have been loads of it.

Clearly I need to make sure I fix this properly, so I'd appreciate advice on my set up:

I've had the car 5 years. When I got it I replaced the original fuel line in the engine bay with fairly generic Halfords hose (SAEJ30R6, 5/16"), and included a plastic inline filter from Ebay, and all connections made with jubilee clips. I had no problems with that set up.

A couple of weeks ago I replaced it all with Gates Barricade Fuel Injection Hose, same bore, (30R14T2), and I fastened it all up the same way with no issue, all connections nice and tight.

When I had the failure yesterday I noticed that the new hose just kept sliding off the plastic pipe of the filter: when I tightened the clip, the hose just slid off: I could not make the connection with any strength at all. not only that, but the hose was leaving black marks all over my hands - it had become a bit tacky.

So I guess my questions are:

1) what (if anything) is wrong with this new hose? Surely it shouldn't be tacky like this? Have I bought the wrong stuff? (my fuel was still E5). For what it's worth it seemed to regain consistency when the engine cooled down - it was pretty hot under there yesterday.

2) I think I have learned the hard way never to use anything in the line that doesn't have a knurled ring for the hose to fit over (my plastic filter didn't). I like the idea of having a filter, but is it a good idea, and can they be bought with that ring, and would it be safe?

3) I used jubilee clips throughout, nice and tight. They seem OK to me, and yesterday's failure really wasn't the clip's fault, but are they generally OK?

Any advice appreciated. In the end I fixed it (for now) with a length of the Halfords hose, direct from the pump to the carb, so no filter at the moment.

I do carry a fire extinguisher, but I hope to avoid using it!

Joe

SAAB96L
V4 Fan

United Kingdom
122 Posts

Posted - 09 Sep 2021 :  16:05:23 Show Profile Reply with Quote
Hello Joe,

An interesting situation and I am pleased to read that you and the car are unscathed; as you say an unnerving experience.

Gates Barricade fuel line is the best you can get TBH and I feel that the issue is to do with the fuel filter. GB hose is available in Metric and Imperial and using the 5/16" ID is the best option rather than 8mm........... thus your choice there is spot-on.

Jubilee hoses are fine or you can use the next class up which is Mikalor clamps - these are second to none and hydraulic companies use little else. Jubilee clamps tend to pinch hoses, whereas Mikalor compress the OD of a hose equally around its circumference forming an even compression throughout 360 degrees. That is why Mikalor clamps should always be used when connecting exhaust sections and not the cheapo U clamps or the equivalent.

When you fitted GB hose to the filter initially, was it a tight fit or slide on easily ?? Ideally, you should feel significant resistance as the hose bites on to the inlet or outlet port of the filter.

For me, the suspect part here is the filter and I wonder if its quality is somewhat questionable. I use and have used plastic disposable filters on all my classics and never experienced your situation - thank goodness.

The filter exit ports should have a billeted end, which as you rightly state assists the hose staying put when clamped correctly.
The filter you have - are the outlet ports smooth ??

Ironically, petrol tends to evaporate instantly when applied to a hot surface and has a very narrow ignition band. The majority of petrol fires are caused by the petrol being ignited by a spark or flame. Conversely, brake / clutch fluid will explode on touching a hot enough surface. Therefore out of the 2x fluids it is brake fluid that is more dangerous................... although I do not expect folk to test the facts !!

A photo of you fuel filter will be useful if possible.

Regards.

Richard.

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melle
V4 Guru

United Kingdom
3388 Posts

Posted - 09 Sep 2021 :  18:07:36 Show Profile Reply with Quote
I know the feeling, experienced something similar years ago when I was doing about 80mph overtaking a few lorries on the Autobahn and the fuel pipe came detached from the carb. I first smelled fuel and the all of a sudden there was a fine mist everywhere, the windshield wipers could barely keep up it seemed.



You normally shouldn't even need hose clamps on disposable plastic filters, and if overtightened they do more harm then good. There's hardly any pressure in the hose, so friction should do the job just fine.

www.saabv4.com
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Derek
V4 Guru

United Kingdom
2041 Posts

Posted - 10 Sep 2021 :  12:42:02 Show Profile Reply with Quote
"Good" filters have retainer lips, sometimes 2 or 3 to suit various size hoses. Don't use tiny filters. Crossland ones are good and not expensive. Forget the 1 ones! Should be snug enough to hold on themselves if the hose and filter sizes match as Melle says. Max they have to cope with is about 5 psi. If you use clips, Jubilees are very bulky and inefficient when that small. There are much more suitable fuel hose clips that can be used for these connections and as a bonus don't cut into you hose. This style, Halfords should have them.
https://www.ebay.co.uk/itm/363500693115?epid=14049099443&hash=item54a254667b:g:3JIAAOSw-pthEmeH
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EdinburghJoe
V4 Fan

United Kingdom
127 Posts

Posted - 10 Sep 2021 :  13:36:39 Show Profile Reply with Quote
Thanks all for the replies. I was using filters without retainer lips, like these:

https://www.ebay.co.uk/itm/353538757452

They did fit snugly onto both the Halfords and Gates hose, tight fit without the clips (even tighter with them). The problem was that the Gates hose just seemed to have got slippery on the inside of the bore when it was hot and full of fuel: the filter just slipped out of the hose and could not be held in.

I've decided to order a couple of these:
https://www.eurocarparts.com/p/pierburg-fuel-filter-441770070 : A bit of a pain that they're not see-through, but I like the idea of metal, with obvious ring to hold the hose on. I'll also get the 'proper' fuel hose clips as suggested.

I'm still puzzled by the behavior of the hose though: I did an experiment dunking a longitudinal slice of the gates hose into hot petrol in a jar: it went tacky on the outside (thick black stain on my fingers) but this didn't happen on the inside, though it did seem 'slippery' as I mentioned above. I'm reassured that the stickiness was only on the outside (when I had my leak hot fuel was running down the outside of the hose, and I know it's not rated for immersion), but is the slippyness on the inside normal?

Joe
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melle
V4 Guru

United Kingdom
3388 Posts

Posted - 10 Sep 2021 :  13:59:01 Show Profile Reply with Quote
I usually use Mann WK31/2 filters, which don't have a retaining lip, never had an issue. Not had a problem with no-name 1 ones either.

EDIT: I typically buy fuel filters in bulk and haven't bought them in a while, but I don't think the Mann filters cost me much more than 1 apiece.

www.saabv4.com

Edited by - melle on 10 Sep 2021 14:04:16
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Derek
V4 Guru

United Kingdom
2041 Posts

Posted - 11 Sep 2021 :  14:33:08 Show Profile Reply with Quote
For this application I prefer see through, if just for the reassurance of checking that the fuel is coming through OK.
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andydeans3
V4 Guru

United Kingdom
1550 Posts

Posted - 20 Sep 2021 :  21:15:40 Show Profile Reply with Quote
Sounds like a hairy experience Joe.
Others have said most of what I would have said.

The very important one about the fact that petrol is unlikely to ignite simply by falling on to a hot exhaust, is worth repeating..

I've started using the glass fuel filters that can be unscrewed, and opened, to facilitate cleaning the filter.
https://www.ebay.co.uk/itm/223958853775

I try to avoid using jubilee clips on petrol pipes, always better to use proper petrol hose clips.

Andy



1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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