Petrol Pump

[alexander]

My Javelin has a fuel starvation problem and I will be checking the manual pump first but just wondered if anyone can recommend an electrical pump that’s not overly noisy.
Thanks

[Keith Clements]

rebuild kits available from club better than electric conversion.

[David Morris]

Hi Alexander,

Sorry, in this case I don't entirely agree with Keith. Yes, of course rebuild kits are probably available from the excellent JCS, but you might not be solving your fuel starvation problem, especially in this hot weather.

I had a similar problem with my Javelin, that I eventually dubbed the 'Morrison's effect'. The problem was that I would drive her down to our local Morrison's for some shopping, with everything working well. Leave the store about 20 mins later with my shopping and would she start? No way. Admittidly this happened more often in warm weather, but after sitting in the car for another 20 mins, she would eventually start. I put this down to fuel evaporation. I tried wrapping the fuel pipes in asbestos rope, and this didn't really help.

My eventual solution was to do away with the mechnical pump altogether, just as Jowett's did on the Jupiter and to fit an electric pump. You can then position this somewhere handy under the bonnet, but well away from the engine heat.

In case you want to do the same, the model I used was made by Hardi in Germany and if you search on eBay under the old QH reference number of
AUF214Z you will see the one I used, described as suitable for a pre-1970's Mini currently at £79.25 with free p&p.

You may have to fit a pressure reducer, as I had to, as the fuel pressure from the pump may defeat the float valves and cause flooding. However, with the electric pump, you get excellent starting and a reassuring, but quite quiet pulsing sound from the pump. Being electronic, there is no need to give it a thump with a spanner if it packs up, as you used to with the old AC pumps fitted to Morris Minors and presumably in the Jupiters too, although I have never owned a Jupiter?

Hope this helps,

Stay safe,

David

[Forumadmin]

I accept the problem may be caused by heat causing a vapour lock. I also accept that having a petrol pump that you can switch on and off is an advantage as you can hear when it is going, thus telling you if your carbs are flooding or not receiving any petrol. But electric pumps with points also have their issues. Electronic ones seem to be unreliable in Jowetts perhaps due to the high voltages that can appear on the battery feeds due to poor earths, mechanical regulator and unsurpressed ignition.
Check when your pump seems to have stopped working that there is no petrol in the carb bowl. Priming the pump manually may tell you if it is a vapour lock.
Bear in mind too that UK petrol is not designed for the high temperatures we are currently getting.
The position of the carbs right above the exhaust also does not help if you have just parked up, as this can boil the petrol in the carbs causing over rich mixture.

[Nick Webster]

Is this petrol starvation manifesting itself as a flat spot while accelerating or the engine fading out above a certain speed (or engine revs)?

Nick

[Keith Clements]

Further to Nick's request for more information, you may be wrongly diagnosing the cause as fuel starvation.
Ignition coil, spark plug, carb jet, or air intake issues can cause sudden loss of power with throttle down fully.
Also if petrol is older than 3 months then try with fresh petrol.

[alexander]

Hi All
Thanks for reply’s the car runs up to fifty then struggles, if I lift off then go again the car picks up and speed increase, this repeats as I try to get the car to go quicker.
So far I’ve changed dizzy cap ,rotor, points, plugs. Changed the washer/spacer under the needle valve from .080 to .060 and now at .040 .
I used the car Sunday to display at the BL day at Gaydon after standing in the sun all day ad driving home in 80F heat there was no improvement but the car showed no sign of cutting out.
Yesterday I took the pump off and changed the diaphragm and cleaned the jets in the float bowels , ran out of time to test so that’s today , will get back with update.
Thanks again
Dave

[Keith Clements]

If still bad .
Check polarity of ignition coil matches polarity of car. Can use lead pencil method.

Try running with the petrol cap off. Breather may be blocked.
Try blowing back through the petrol intake to the pump to clear any blockage.
Try running without air intake tubes.

[alexander]

Check polarity of ignition coil matches polarity of car. Can use lead pencil method.
Checked already, even tried new coil and condenser

Try running with the petrol cap off. Breather may be blocked.
Tried this no change.

Try blowing back through the petrol intake to the pump to clear any blockage.
Did this yesterday while I had the compressor out to blow through float bowl jets

Try running without air intake tubes.
Not tried this will give it a go. But did clean and re oil filter.

My test this morning was the same, runs nice to fifty then had to back off then press pedal again to get small improvement.

Question could progress jets being blocked give me this problem or as I’ve never been sure that I’m adjusting the tappets correctly even through I try to follow “The Jowett Patient” notes give m e this problem.

Thanks again for your help
Dave

[David Morris]

Hi Dave,

Wow! You have tested quite a few things...well done!

My only suggestion is to check the ignition. She might be too advanced? I find the 'sweet position' is, statically, just a bit retarded from TDC. Are you using the flywheel marks to set TDC? They can be way off; I suggest you check TDC from Cylinder No. 1, using some fairly stiff wire down the plug hole.

Does the engine rev sufficiently, or does she not want to go beyond about 3000 rpm, which is around 50mph in top gear?

As for the tappets, the old Jowett advice is to ignore what's in the book and set the gaps so that both exhaust and inlet push rods can just rotate easily when the engine is COLD. Don't do this with the engine warm.

Hope this helps,

David

[alexander]

Thanks David will check tdc your method at the moment I set tdc at the1/2 mark on the fly wheel.
I had not thought of checking the revs so will add that to the to do list, then check tappets again.
Dave

[alexander]

Just checked that the car revs past 3000 and with no load the revs went to nearly 5000 ,I chickened out then as not certain what max rev are for a javelin.
I will now remove petrol cap again and remove air intake rubbers and try on the road if this does not work I will check tdc David’s method and check tappets.

[Keith Clements]

Ah. Perhaps it is the vacuum advance. Timing light should tell you if it is working. Should give extra 10 deg.
At 2000 rpm with vacuum pipe disconected should have 22 deg adv . connect vacuum pipe should get extra 10 when throttle blipped.

what colour are the plugs?

[alexander]

No improvement with petrol cap and carb intake rubbers removed. Timing seems ok and advances as it should. It still seems like fuel starvation so will recon spare pump just in case the one I did last week has other problems that I can’t see. Following the thread on timing but still think it’s fuel related due to slight improvement when lifting off and going again which I assume is the bowls filling up when demand for fuel drops.

[Keith Clements]

With the carb bowls removed, and a recepticle placed under each float valve, manually pump the petrol pump. How much petrol in cc is pumped out with each pump and is it equal both sides?
Now do the same on the starter for one rotation. Is it the same?
This might uncover an issue with pump actuator, pipe work or pump valves.
Some maths might also give you an estimate of how much fuel is required for each rev of engine at 50 mph!

I have a faint recollection that a faulty pintel valve can upset the fuel pump, because there is too much vacuum at one side of the pump diaphragm. Leaving oil filler cap off should prove this, perhaps fit cap with hole so as not loose oil.