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Fuel Priming system.


Wagger

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Last Autumn I reconditioned and fitted a mechanical fuel pump. The one with the glass bowl. I left an electric one in series with it in line 'Before' it as it has a small inline filter. I tested both pumps fitted before and after one another, and they both drew fuel through each other with no bother. 

I have not started the car for three weeks and today the main car is being collected for MOT. Therefore I need the Vitesse. It would not start. Fired briefly with no Choke, so I used the lever to 'Prime' the system. Still no joy even after 2 minutes of operating the starter 5 secs on, 10 secs off.

I then connected the electric pump and waited about 15 secs until I heard the note change. Car then started with no hesitation. I have found a momentary Pushbutton switch,  will now connect it to the electric pump and fit it under the dash. It will save a load of bother.

In all of my 'Playing around' in the Autumn, I realised that the glass bowl pump acts as a very good filter when fitted before the electric one. I used this set up it to drain the tank for cleaning purposes. All of the heavy crud sinks, and the floating stuff gathers on the gauze. With the car stationary and not running, it does not get stirred up. It is very simple to clean but don't use an aqua vac or you'll be handling a 'Flame Thrower'. How did I find that out? Don't ask! It was not very exciting. I have heard louder farts.

I do not run on 'Reserve' now as I can see milky stuff in the glass bowl. I have found it impossible to stop rust collecting in the bottom of the tank. Back in the 1970's I never used reserve on my 1600/6 for the same reasons.

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Many people don't use the priming lever correctly, including me... found that out the hard way. The lever should not be pulled up from rest, but initially pushed down from rest. Down as far as it will go, and only then pulled up. This moves the diaphragm fully and gets the fuel through. Simply pulling it up from rest until it stops, and letting it drop again, doesn't activate the full mechanism, so as the fuel is moving slowly it often seems as though nothing is happening. I discovered this very recently on the 1200 Estate engine and the difference in fuel shooting out of the end of the fuel line is amazing.

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but the reserve is not anything other than the suction tube is just lowered deeper into the fuel 

there is no separate tank or anything clever inside the main tank just a curved dip tube that lowers its end when you rotate the lever 

its all the same fuel from the same one and only tank 

the short rubber hose that links the dip tube to the supply pipe is often ignored /is degraded/ often very loose 

it will then suck air  but wont lean fuel as its above the head of the fuel level its a hidden place that needs a regular check

Pete

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Thanks Colin for the priming info. I had forgotten that one even though I noticed it after re-conditioning the pump. I have no problem with fuel flow so long as I use the car weekly. However, I always get discloured fuel if I use reserve. Tank has been out, shaken with tumbling pebbles in it, cleaned out and re-fitted. When budget allows, I'll find another tank.

When I pump the fuel out, it is virtually empty, using torch to view through the sender hole.

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13 minutes ago, Pete Lewis said:

the milky is probably air ...check that short pipe 

Pete

Your are correct Pete. If I flex it, there are visible cracks. Job for tomorrow is sort the spares box. There are several different sizes in there.

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Changed pipe and all ok. As it is a 'Syphon' there will always be air at the 'High' point. I guess this does not really matter. The only way of purging it is to force fuel through in reverse at a very fast rate. I won't bother unless I have to.

My post was also to suggest using the old pump as a filter for those who fit an electric pump. It can be left in situ, disabled, or bolted elsewhere. It is very easy to clean and all crud is visible.

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