fuel flow problems

Dear All,  I have had a recurrence of a previous problem with very similar symptoms. to this post.  To summarise, when I first got my Speed 20, 3 years ago, it kept stopping every half-mile. Over that first traumatic weekend I eventually ripped out the whole ignition and piggybacked a (relatively) modern Sparkrite ignition and coil (all fully reversible with original coil left in situ). It still kept konking out on me.  It turned out to be a fuel blockage in the pipe from the tank. Since then, I have had the problem again, but fortunately I have had the main/reserve changeover switch refitted, so was able to get home, literally bypassing the blocked pipe.  Modern petrols seem not to mix very well if left for a while. I had a similar problem in my Austin Healey 3000 a few years ago. So try blowing back through the pipe(s) (mark one lips at the roadside) and if sucessful, be prepared to drain the fuel tank when you get home.  Steve Laurence, DYE 166. Posted by g7psz 24/10/2012 20:01:48

here is a quick update,  the new stainless steel fuel tank has been painted (special etch primer etc..), refitted to the car and ....still the float chambers will not fill up. At least now the problem is so serious that the car just will not start without taking drastic steps to supply fuel to the carbs. It runs fine with the float lids removed and a jug of petrol keeping things topped up!   So, in desparation, I bypassed the clear "glass" filter and fuel pressure gauge which I had previously fitted to assist in fault finding and the *****y thing worked!!! I haven't yet investigated what might be wrong with three short lengths of rubber tube, a T piece and a clear see-through filter but I expect I will find some debris (which allows pressure, and good flow into an open container but will not flow into the carbs) or possibly a flap of rubber inside one of the hoses where it was pushed onto a metal tube of some sort.  Next step, take it for a drive to the petrol station to fill up and check all the possible leak points on the tank and if all goes well start to exchange various bits back towards the original installation of twin fuel pumps and pipework.  Plus refitting the boot lining panels.  One bit of positive news, the fuel guage seems to be working for the first time in my ownership (an earth wire to the sender unit seemed to be needed but was previously missing)  Fingers crossed, this might be the end of this frustrating and time wasting exercise - just in time to put the car away for the winter.  thanks to all for reading and contributing to this thread  Dave Posted by DaveT 25/10/2012 11:49:04

Fingers crossed indeed Dave! I hope that its all sorted for you now.  Regards, Paul. Posted by pryantcc 25/10/2012 20:44:35

Where, in line, did you install glass fuel filter & pressure gauge?  Anxious to hear your final findings as I am installing a similar Malpassi Filter King on my 2013 Peking to Paris VW Beetle and want to ensure I don't have related problems.  Glad you have resolved and looking forward to reading final chapter. Posted by johnlayzell 27/10/2012 02:12:28

Hi, this is not quite the final chapter!  The car successfully reached the local fuel station and back with some minor misfiring but nothing that worries me after all this time. However the new fuel filler to tank rubber hose (which I was not 100% happy with) is leaking so I stopped at about one quarter full. A more flexible hose and some heavy duty clamps (bolt and barrel) are on order to try to accomodate the various diameters of the fuel filler pipe, the tank inlet pipe and its swage.  The weather this past weekend put me off any further testing - but I am reasonably encouraged so far.  Going back to John's questions, the system was (in order) fuel tank, two parallel feed pipes, small K&N filter in each feed pipe, reserve / main selector tap, pump(s), T piece to pressure gauge, "glass" fuel filter, 3 carbs. The T piece and "glass" filter have now been removed and subsequent investigation appears to indicate that the mesh within the filter was too restrictive. I don't yet accept this as the answer but could not come up with anything better based on blowing through the assembly and then through each component in turn. I dismantled the (clean) filter and on reassembly it seemed better!!! perhaps the plastic filter was overcompressed.... Posted by DaveT 29/10/2012 12:39:57

A small alarm bell rang when you said the car easily started from cold without any choke.  I had problems with similar easy starting without choke and running rich, but without misfiring when hot. I found there was a spring missing in the choke mechanism. I wrote a brief article in a recent Bulletin about how I fixed it.  A similar problem may be confounding (but not being the main cause) of your problem.  Coincidentally, I have a similar blockage in my [i:u8hiwmir]main[/i:u8hiwmir] fuel line from the tank that you had, but the reserve is fine. Another winter job to deal with.  Steve Laurence,  DYE 166 Posted by g7psz 06/12/2012 11:01:07

at last I seem to be making progress. The car has just made to the Fougeres Rally and back (about 800 miles) although it did break down twice.   The first fault started as a fairly significant missfire but we carried on as it was raining and made it to the first hotel stop in France. The next morning the ignition was completely dead - ie much easier to fault find. Eventually I found that the earth to the points was open circuit due to the two screws holding the insulated distributor base having come loose. I had changed this two weeks previously to overcome a stripped thread (previous owner) in the points fixing screw that provides the earth.   The second fault (on the way home), again a missfire, but this time not too serious whilst travelling at speed around the M25. First sign of trouble was when the engine coughed as I put the pass lights on (it was starting to get dark). Then at the toll both for the Dartford crossing the car stopped completely. No lights and no ignition. About 40 minutes later, I found a loose connection in the back of the fuse box / regulator.  All this was whilst using the reserve petrol feed from the tank because I have fitted a non return valve in the main feed which is not permitting flow - yes it is the right way round! I suspect it is either designed for a higher pressure system (fuel injecton) or I have an air leak before the pumps, (only in the main feed) that is reducing the vacuum.  The other point is that throughout the rally the ambient temperature was not particularly warm, so although my confidence is growing, I am not totally happy yet  thanks for your interest and support  Dave Posted by DaveT 31/05/2013 04:48:39

I have now changed the non return valve in the main fuel feed line and (in the garage) the new larger one seems to be working. I will report back after next using the car on the road. The reserve line remains without a valve - I shall probably leave it that way. Posted by DaveT 01/06/2013 17:26:11

Great stuff Dave, thanks for updating us on progress! Posted by pryantcc 04/06/2013 09:54:27

1) Try checking the fuel FLOW from the pumps outlet into a container (safely) over an extended period to see if it reduces or varies. It may be that there is debris slowly clogging the line or the pump under suction/operating conditions.   2) Check the pump electric feed for amp supply over an extended period to see if there's any variation, perhaps a faulty ignition switch or bad connection not passing full current if it warms up?   3) By-pass the reserve tap - the cork seals are notorious for wilting and leaking air AND partially blocking the fuel outlet due to distortion.  4) If not positive, rig up a can of fuel underbonnet (safely) and run the car on the road with gravity feed and see if the problem persists.  5) Even though you have overhauled the ignition, substitute another ignition coil, condenser, cap & rotor individually and test as there are a whole load of duff units of these around. Any of these can fail under load as they 'warm-up' after a few miles and give your sort of symptoms.  Adopting a systematic process of diagnosis will be much better.  Nick Simpson. Posted by Nickalvis 06/10/2013 11:58:09