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Special Sports fuel issue

Crossley Stephenson
Posts: 251
Joined: Wed Feb 10, 2016 9:15 pm
Location: Victoria, Australia

Special Sports fuel issue

Post by Crossley Stephenson » Thu Dec 12, 2019 11:19 pm

I am still experiencing ongoing, intermittent fuel supply issues. The symptoms are similar to what would be experienced if something were loose in the petrol tank and occasionally blocked the pick up but there is nothing in there!
Thus far I have rebuilt the mechanical fuel pump and by-passed the reserve fuel tap (corks were very dry). With each action I test drive and think I've solved the problem but alas it reoccurs unexpectedly...happily motoring along and then the engine just stops. Wait a while, prime the fuel pump (it takes some priming too!) and off we go again. When the problem first occurred I felt the pump was taking far too long to prime and was probably drawing air from somewhere hence the pump rebuild and by-pass actions. The pump still feels like it takes too long to prime and my suspicion is that air is still being drawn in somewhere. The prime candidate now (no pun intended) is the Petrol Gauge Tank Unit Joint (Parts Catalogue pg 45 item 12) that appears to be a cork joint and without yet removing it it looks very dry. I will remove and inspect and if it is US can make another cork joint but is there some other modern material that would be better to form the joint?
Any of you wise people have any other suggestions?
Cheers
Michael

Big Col
Posts: 437
Joined: Tue Feb 16, 2016 12:45 pm
Location: Leeds

Re: Special Sports fuel issue

Post by Big Col » Fri Dec 13, 2019 12:10 am

I had similar problems with an SP. In my case it was an in line filter which was partially blocked. It allowed some fuel threw but not enough when the engine was under load for slightly prolonged periods. Is there a chance that your pipes have a touch of thrombosis?
If you are suggesting that your gaskets are dry then I would suggest that they are not immersed in fuel as the sender unit is atop the tank. In that case then the top of the tank would have air in it anyway all the time and have no ill affect upon the pump picking up fuel. (Presuming of course it isn’t a pressurised system.
Colin,
I may be slow but I’m rough as well !

Crossley Stephenson
Posts: 251
Joined: Wed Feb 10, 2016 9:15 pm
Location: Victoria, Australia

Re: Special Sports fuel issue

Post by Crossley Stephenson » Fri Dec 13, 2019 5:39 am

Thanks Colin and of course the joint for the sender would make no difference as the pick up immersed in fuel. I took the in-line filter out ages ago when the problem first started. I'm beginning to like the thrombosis suggestion or possibly a pin hole in the fuel pipe. I didn't replace the fuel lines when I restored the old girl about 10 years ago. I might try substituting a new fuel line and see if that does the trick.

Anymore suggestions from anyone - I have tried to think it through logically but a bit of brain-storming from others is welcome.

Cheers
Michael

Peter Grant
Posts: 215
Joined: Thu Mar 10, 2016 10:02 pm
Location: Sydney, Australia

Re: Special Sports fuel issue

Post by Peter Grant » Fri Dec 13, 2019 8:42 am

Hi Michael,
I’m stumped.
It isn’t the coil is it?
My DE would stall after a run if the revs dropped and it was the coil which got hot and I couldn’t start the car until the coil cooled down.
That is my first thought, for what it is worth.
Cheers
Peter G

qantasqf1
Posts: 149
Joined: Mon Mar 07, 2016 10:13 pm

Re: Special Sports fuel issue

Post by qantasqf1 » Fri Dec 13, 2019 9:21 pm

That’s a good point, Peter. The symptoms suggest it may well be the coil and not fuel related at all. Replacement coils are pretty cheap so I would definitely replace it if only for elimination reasons.
Steve

Crossley Stephenson
Posts: 251
Joined: Wed Feb 10, 2016 9:15 pm
Location: Victoria, Australia

Re: Special Sports fuel issue

Post by Crossley Stephenson » Sat Dec 14, 2019 5:34 am

Thank you Peter and Steve.

I have tested the coil and get 1.9-2.0 ohm on the primary circuit and 16.0 ohm on the secondary circuit which seems to be withing spec. But just in case I'll try a substitution.

Cheers
Michael

Marcel Renshaw
Posts: 378
Joined: Fri Feb 12, 2016 8:44 pm
Location: Derbyshire

Re: Special Sports fuel issue

Post by Marcel Renshaw » Sat Dec 14, 2019 10:01 am

Just a thought, if it’s taking some priming when it stops have you checked the floats?
I had a leaking one on my Consort which caused running issues.
There are some military specification ones which won’t leak and should not be affected by ethanol based petrol.

Crossley Stephenson
Posts: 251
Joined: Wed Feb 10, 2016 9:15 pm
Location: Victoria, Australia

Re: Special Sports fuel issue

Post by Crossley Stephenson » Tue Dec 17, 2019 8:16 am

Have checked the floats Marcel, all OK.

Have swapped the coil - the old mechanics adage: most fuel problems are electrical. Thank PG for the suggestion. Will need to look at condensor too.

Being a cantankerous old car I have been out to the shed yesterday and today - primed the carbs, less than a doz strokes, and she fired up no worries. Ran her up to op temp and idled for 15 minutes, all good.

Too hot here tom. but a road test on Thurs. will keep you posted.

Cheers
Michael

User avatar
John-B
Site Admin
Posts: 1257
Joined: Tue Feb 09, 2016 9:10 pm
Location: Salisbury, UK
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Re: Special Sports fuel issue

Post by John-B » Tue Dec 17, 2019 9:37 am

Crossley Stephenson wrote:
Tue Dec 17, 2019 8:16 am
Too hot here tom. but a road test on Thurs. will keep you posted.
Cheers
Michael
Too hot? I've just realised you are in Oz. Fuel vaporisation? Fuel gets through until it gets too hot and creates an air gap. Stop for a few minutes and the vapour gap disappears. Check fuel lines near the exhaust or run with the bonnet off, if possible (as a test only!).

No one above has mentioned fuel vaporisation, but it has been mentioned in lots of other topics.

Warsash 2
Posts: 307
Joined: Sun Feb 28, 2016 1:53 pm

Re: Special Sports fuel issue

Post by Warsash 2 » Tue Dec 17, 2019 11:30 am

Hi
I had fuel vapourisation on my V8 after fitting a stainless steel exhaust. I lacked the fuel pipe were it ran near the exhaust with material I got from a hydraulic hose specialist not pretty dut it works and just slips over the pipe.
Regards

Colin

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