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Special Sports fuel issue

Crossley Stephenson
Posts: 215
Joined: Wed Feb 10, 2016 9:15 pm
Location: Victoria, Australia

Special Sports fuel issue

Post by Crossley Stephenson » Mon Feb 04, 2019 7:44 am

OK Gurus,

I went to take the SS out for a run last week and it "failed to proceed" the first time a mechanical problem has stopped me. It ran perfectly when put in the shed a couple of months ago.

There is spark so the problem is fuel. The pump simply won't pull the fuel through. I immediately suspected the reserve fuel tap. Removed the tap and the corks were dry, possibly allowing air in. By-passed reserve fuel tap. No improvement. Removed the pump, all seemed OK. Refitted pump, no improvement. Where to next?

BTW there is plenty of fuel in the tank. Seems we are drawing air from somewhere stopping the pump from working as it should.

Suggestions welcome.

Cheers
Michael

Phillmore
Posts: 805
Joined: Sat Feb 13, 2016 1:25 pm
Location: Worcestershire Herefordshire border

Re: Special Sports fuel issue

Post by Phillmore » Mon Feb 04, 2019 9:11 am

After a two month lay up the pump will need a lot of priming or engine spinning to get the fuel from the tank to the carbs.
Andy

1954 Conquest Mk1, 1956 Conquest Mk2, 1957 Conquest Century Mk2, 1955 Austin A90 Westminster

Db n j
Posts: 196
Joined: Sun Mar 13, 2016 8:55 am

Re: Special Sports fuel issue

Post by Db n j » Mon Feb 04, 2019 10:01 am

I think Andy has a good point.

(from my experience, the fuel pump hand prime can be ineffective at some points on the cycle (ie the pump is driven by a cam - at its high point, this
can prevent the hand-primer from being effective in lifting fuel - move the cam by pushing the solenoid button to turn the engine a little)

To check the pump, remove the fuel input and replace with a hose and petrol can. (isolate the tank and switch)

Remove the rubber pipe before the carbs and catch the fuel in a bottle. (see that the petrol is leaving the pump)

Remove the carb bowl tops to see if the float needles are stuck shut (see that the petrol is getting to the bowl)

Stan Thomas
Posts: 466
Joined: Sat Feb 13, 2016 2:14 pm
Location: Penkridge. Staffs.

Re: Special Sports fuel issue

Post by Stan Thomas » Mon Feb 04, 2019 10:28 am

Prepare for a gob full of petrol!!

An old trick of the trade is to remove the outlet pipe from the pump and attach a length of tubing and suck until fuel comes through - but if you use clear plastic tube you can stop sucking just in time.

This wets the reserve tap seals and the valves in the pump etc. if they are dry.

Might give you a nasty taste - but a few "tinnies" (as they say in Oz) will soon take that away.

However, try Phillmore's suggestion first, as the pump lever might be on the top of the cam. There should be slight resistance to hand-pumping if the pump is O.K. which goes limp once the fuel has filled the float bowls.

Crossley Stephenson
Posts: 215
Joined: Wed Feb 10, 2016 9:15 pm
Location: Victoria, Australia

Re: Special Sports fuel issue

Post by Crossley Stephenson » Tue Feb 05, 2019 1:27 am

Tks Andy, David & Stan

I am aware of the cam issue having been caught before and a quick push on the solenoid usually solves that problem.

I have never had to use the hand primer more than about 20 times - until it is obvious it is no longer pumping (it goes soft) - to get sufficient fuel to start the car. I must have pumped about a 100 times his time.

I have tried Stan's suck trick - nothing

I have tried David's bottle with petrol on th inlet - nothing

The pump simply won't pump. The diaphragm is moving up and down and sounds like it is working but I fear I need a diaphragm kit as it seems likely one or more of the valves has failed or the diaphragm has a leak - modern fuel?

Now to find something locally! Goss used to make kits here in Oz but they were taken over and the range 'rationalised' might have to talk to Mr Beales.

Cheers
Michael

Crossley Stephenson
Posts: 215
Joined: Wed Feb 10, 2016 9:15 pm
Location: Victoria, Australia

Re: Special Sports fuel issue

Post by Crossley Stephenson » Tue Feb 05, 2019 3:19 am

I have now removed the pump, taken it apart and inspected everything, nothing obvious. Changed the valves for some others I had. Set up a test on the bench with a bottle of petrol to feed the inlet and a pipe to catch anything that came out - zilch. The diaphragm must be faulty, after all it was working last time out.

I have found a diaphragm kit her in Oz but it is cheaper to buy from Beales even with postage costs.

Watch this space
Michael

Sydsmith
Posts: 696
Joined: Sun Feb 14, 2016 11:15 pm
Location: Aberystwyth Wales

Re: Special Sports fuel issue

Post by Sydsmith » Tue Feb 05, 2019 9:19 am

Michael, sounds like you are doing all the right things but there should be no need to use petrol to bench test the pump, you should get a good suck when you operate the lever arm or manual lever and hold your thumb over the fuel input, if not you have a problem.

As you seem to have surmised most likely problem is a hole in the diaphragm or duff valves. Syd

Peter Grant
Posts: 167
Joined: Thu Mar 10, 2016 10:02 pm
Location: Sydney, Australia

Re: Special Sports fuel issue

Post by Peter Grant » Wed Feb 06, 2019 5:46 am

Hi Michael,
I once had this issue on the DE, heading north to our Rally in Queensland after the car had a six month holiday in Wodonga.
The mechanic in Wauchope thought it was the valves sticking.
When you put the kit in don;t forget to fit the diaphragm "extended" before you tighten things up. John Steel taught me that.
I have a couple of kits at home which are for the DE 36: if they are the same (and i will check) I can always send you one and you can get me a replacement in due course.
Cheers
Peter G

Db n j
Posts: 196
Joined: Sun Mar 13, 2016 8:55 am

Re: Special Sports fuel issue

Post by Db n j » Wed Feb 06, 2019 7:17 am

Michael.

The service kit is used very widely, and not just on Daimlers.

I think it fits the AC Fuel Pump Types "T" and "U" (and maybe others) - I would think yours would be a "U".

My bet is that you can get one locally.

Crossley Stephenson
Posts: 215
Joined: Wed Feb 10, 2016 9:15 pm
Location: Victoria, Australia

Re: Special Sports fuel issue

Post by Crossley Stephenson » Wed Feb 06, 2019 8:42 am

Peter and David

Thanks for your input. I have found a supplier for an AC repair kit here in Oz at $120 +GST so decided to order from Beales at £24. I agree they are similar to many other AC pumps fitted to many UK cars, probably interchangeable.

The more I think about it the more I suspect a valve sticking, despite cleaning them etc etc, the diaphragm may have a hole - damned modern fuel - but how would I know.

When I put my finger over the inlet and then pump the lever it creates a vacuum?

I am bewildered.

Hopefully a repair kit will fix the problem. Peter, I will call you about ditting the diaphragm 'extended'.

Cheers
Michael

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