Fuel union on P2
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Re: Fuel union on P2
I really thought that changing back to the mechanical pump had cured my problem but once warm I was still getting fading and surging which I put down to vaporisation although I was not convinced from what people have said that it happens whilst you are going along? Is that correct? Anyway I changed back to a new cheapo electric pump and that was disastrous (not the pump though) It started off well but died at the bottom of the nearest test hill and died again and again until nothing would restart her especially the flat battery. I had to be towed home ignominiously (the first time). I did see that there was lots of air in the fuel line (after the pump) and I mean more air than fuel probably. So that issue wasn't the old pump failing and hasnt gone away. But why only when the engine is hot? And if so much air is getting in why no leaks out?
In the meantime I have replaced the condensor on the distributor. I have soldered all the plug lead washers in place and retrieved old acorns and washers as the new acorns are not threaded long enough and wouldn't tighten down fully. The old washers were also twice as thick. All to no avail it seems. However I am bit suspicious of the centre pin sticking but that doesn't seem to fit the symptoms either.
I am at a loss what to do again. Unless that point about localised boiling in the block applies- she is getting much hotter than before the valves were replaced - maybe with a faulty water pump ? Or maybe the inlet manifold is not tight enough? Any suggestions gratefully recieved
In the meantime I have replaced the condensor on the distributor. I have soldered all the plug lead washers in place and retrieved old acorns and washers as the new acorns are not threaded long enough and wouldn't tighten down fully. The old washers were also twice as thick. All to no avail it seems. However I am bit suspicious of the centre pin sticking but that doesn't seem to fit the symptoms either.
I am at a loss what to do again. Unless that point about localised boiling in the block applies- she is getting much hotter than before the valves were replaced - maybe with a faulty water pump ? Or maybe the inlet manifold is not tight enough? Any suggestions gratefully recieved
Re: Fuel union on P2
Nothing would replace a systematic analysis. I repeat my suggestion to hook an up alternative fuel supply, directly to the carburetor. For inspiration see here: https://www.youtube.com/watch?v=KVwBOlCSPx8
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Re: Fuel union on P2
Thank you for your calming words Luli- you are right I have to pursue a logical sequence of tests to find this problem. I did test the fuel line and it maintained pressure for about 20 minutes although this was inconclusive because I couldnt get a good seal on the garden spray pump that I was using to pressurise so that lost pressure. I shall now connect a flexible supply direct from the tank to the pump and carb etc in turn and test out the various options for leaks one by one.
Re: Fuel union on P2
Rob - be careful, if the dip tubes in the tank are split, and it is common, you will still have the same problem because you will still pull air in. You need to rig up an alternative "tank" so that you are not using any of the original installation before the pump.
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Re: Fuel union on P2
Yes Stewart I keep looking at the dip pipes but damned if I can see anything split there. Would a split be invisible to the naked eye? Also I keep swapping to the reserve pipe which makes no difernece so would they both go at the same time? Are the even replaceable except by scavenging salvaged ones? (The unit I replaced had been marmalised with one pipe cut off and soldered shut and the other bent round through 90 degrees so that a disposable filter would fit so not much hope there)
Re: Fuel union on P2
Pressurize it with air, immerse in water and look for bubbles, which will indicate where the leak comes from - if it does.
See also here: http://wp.me/pXLKy-1nF
See also here: http://wp.me/pXLKy-1nF
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Re: Fuel union on P2
I have now pressure tested the reserve tank unit and dip pipes fully immersed under water and no bubbles so that eliminates that source of the leak. I have also pressure tested the fuel line between the tank connection and the pump and found no obvious leaks- the pressure did drop gradually (from 6 bar to 3 bar in about 30 to 40 minutes on average) but that could be at any of the temporary end connections or indeed back through the garden spray itself which I was using to pump up the air pressure. I did try connecting the tank direct to the pump with a flexible but the pump could not draw any fuel into it - I tried to prime the line with a hand syphon but that did not work either so that exercise told me nothing really. I cant think of any other test which might tell me where the leak is so (given that it is before the pump) I shall probably just reconnect everything and see if the problem is still there.
Re: Fuel union on P2
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- Posts: 320
- Joined: Tue Oct 22, 2013 8:04 pm
Re: Fuel union on P2
Thanks Luli for that interesting test rig illustration which I hadnt seen before, However I dont feel it is the pump as I am using a brand new electric pump (very cheap and noisy but it works) and it displays the same issues. Also previously I swapped to the mechanical pump and this still displayed the same problem - although admittedly I managed a 100 mile round trip and it only started to misbehave on the return leg.
Still plenty bubbles in the line this morning when she warmed up in the garage having reassembled after the last inconclusive tests. I did find the manifold bolts would take some tightening up - after the head had been refitted recently (I used 30lb ft as I couldn't find any guidance on that) but I dont think that would be implicated.
Still plenty bubbles in the line this morning when she warmed up in the garage having reassembled after the last inconclusive tests. I did find the manifold bolts would take some tightening up - after the head had been refitted recently (I used 30lb ft as I couldn't find any guidance on that) but I dont think that would be implicated.
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Re: Fuel union on P2
I realise my problem may be getting a bit boring (it is for me too to be honest) but I am under pressure to solve it because I have committed to a rally to France in just over a month (RRAF =Rotary Retro Automobile Fellowship) So please indulge me some more. I managed unwittingly to replicate the engine failure in the garage today (having removed a section with in line filter to test the joints again - still air bubbles). Anyway being stood right next to the pump it sounded as though the (electric) pump was struggling before the engine stopped even though there were not that many air bubbles going through. I had a plug tester on at the time which verified that the ignition was not failing. So I am wondering whether fuel supply starvation is my problem rather than the air leak. Suspects would be the tank vent as I recently coated the inside of the tank (but no seal on the filler cap so unlikely?) a blockage somewhere that moves when warm or perhaps the strainer mesh I made for the dip pipe foot is too fine?
Or even the constricted nature of the new tank connection union (I had this made to the original pattern but cannot see why the orifice is constricted although it seems to be correct)
Or any other ideas please?
Or even the constricted nature of the new tank connection union (I had this made to the original pattern but cannot see why the orifice is constricted although it seems to be correct)
Or any other ideas please?