Pete Lewis Posted May 29, 2019 Report Share Posted May 29, 2019 MkIV has a suction tube down from the top of the tank, So a thought, when you shut down the head of fuel in the dip tube drops and syphon's it all back to the tank The only thing to stop it is pump valve and if the float needle is closed if no air is let in it wont run back . But if fuel has not evaporated from the float chamber , it should start on whats in there. Pete 1 Link to comment Share on other sites More sharing options...
Badwolf Posted May 29, 2019 Author Report Share Posted May 29, 2019 So perhaps a fuel tap between the disposible filter and the engine filter may stop the 'back syphoning', or one in the boot out of the tank. Link to comment Share on other sites More sharing options...
Pete Lewis Posted May 30, 2019 Report Share Posted May 30, 2019 The valve in the pump is the main controller in any thoughts that it is drain back Tap good idea untill it wont start because you forgot to turn it back to ON !!!! Do make sure the tank vent is working .so there is not a vacuum in the tank Pete Link to comment Share on other sites More sharing options...
Badwolf Posted May 30, 2019 Author Report Share Posted May 30, 2019 Pete - I now see it like you. The fuel evapoates/drains from the float chambers, float valves open, air gets into the system so fuel syphons back to tank. I'm sure the tank vent us clear as there was no vacuum when I filled up yesterday. Not sure if there is a correlation between the level of fuel in the tank (it was holding 2 gallons, so quite low) and the amount of run back. I will get a fuel tap for when the car is not to be run for a few weeks. Is this something other members has found and why is the fuel draining/evaporating from the carbs, is this normal? Link to comment Share on other sites More sharing options...
johny Posted May 30, 2019 Report Share Posted May 30, 2019 That sounds perfectly normal although the drain back on the engine side should only reach the same point in the fuel line as the level in the tank. It happens because the carb float chamber has a vent to atmosphere through the air filter which allows air out when filling the chamber plus overflow if the float valve doesnt close properly. I dont think a tap in the line is necessary as if the non return valves in the fuel pump are good it should quickly refill the carbs but its true a higher level in the tank will help.... Link to comment Share on other sites More sharing options...
Colin Lindsay Posted May 30, 2019 Report Share Posted May 30, 2019 +1 to that (pump valves). My GT6 is still off-road and only starts up to move out of the garage, when I need the space, and then back in, and it starts first time every time without excessive cranking. I rebuilt my pump, a glass-topped Delco, with a complete kit including valves, seals and filters and it's always got fuel in it. I think I fitted one of those as it reminds me of the petrol pumps I saw as a child, with the clear glass bit on the side so that you could see the fuel pumping. Some of them used to have a little spinner inside and it was fascinating. Link to comment Share on other sites More sharing options...
Badwolf Posted May 30, 2019 Author Report Share Posted May 30, 2019 Colin - I vaguely remember those pumps Johny - I think the non-return valve on my fuel pump must be shot. Doubt if I can repair it. Never realised til now that it had one. Failing that, for the cost, a small cut off tap between the filters looks to be the best bet or maybe one of these.. https://www.ebay.co.uk/itm/Inline-One-way-Non-return-Check-Valve-Fuel-Gas-Air-Vacuum-Aluminum-6-8-10-12mm/163664093802?hash=item261b23e26a:m:m2HtjcUbjnMtQ6YrmRmd_6g&var=463120832013 I will keep an eye on the situation while the tank is full. Like so many things, I am probably more aware of problems now than I was when the car was running 20 (odd) years ago. Link to comment Share on other sites More sharing options...
johny Posted May 30, 2019 Report Share Posted May 30, 2019 theres two in each mechanical pump, both of which have to seal well and they come in the repair kits but are a bit fiddly to change. You can test them individually by removing the pump filter cover then blowing back through the outlet pipe and next sucking on the inlet. In neither case should air flow but I bet in yours as in mine it will so the easiest option for me was a replacement pump which has worked perfectly although Ive seen recent posts complaining that some produce too much pressure..... Link to comment Share on other sites More sharing options...
Pete Lewis Posted May 30, 2019 Report Share Posted May 30, 2019 here we go sucking an blowing just dont get Doug involved with inlets and outlets or we drift wildly we converted a glass top from a vauxhall cheap to repair a worn old orig glass top ,, swapped the arms over i like them you can see whats going on Pete Pete Link to comment Share on other sites More sharing options...
Badwolf Posted May 30, 2019 Author Report Share Posted May 30, 2019 Not sure which is the correct pump or repair kit for mine as the engine is from a Herald 13/60. May just get the cheap non return valve to try and if it solves the problem think about sorting the pump over the winter. Link to comment Share on other sites More sharing options...
johny Posted May 30, 2019 Report Share Posted May 30, 2019 only one pump for all Heralds at 16 pounds from Paddock or repair kit 8.75. VAT and postage on top.... Link to comment Share on other sites More sharing options...
Badwolf Posted May 30, 2019 Author Report Share Posted May 30, 2019 Thanks Johny, much obliged. Link to comment Share on other sites More sharing options...
poppyman Posted May 30, 2019 Report Share Posted May 30, 2019 Paddock ones are decent make and seem to last as well Tony. Link to comment Share on other sites More sharing options...
Badwolf Posted May 30, 2019 Author Report Share Posted May 30, 2019 1 hour ago, poppyman said: Paddock ones are decent make and seem to last as well Tony. Tony - Thanks for the endorsement on that. I'm going to put either the service kit or a new one on my parts list. As long as it does the summer, I can take my time over the winter when its too cold to do the paintwork. so much of this has been new to me and I would (as normal) not have been able to sort it out without everyone's input. She is now ticking over and revving up nicely in the garage and I will see what happens on Saturday when I next go out. Will try the Italian tune up for the backfire then. I finally remembered the problem which caused the last backfire problems, the choke wasn't coming off at the carb when pushed in. Lubricated all the linkages and will see if that sorts it. Now, as long as she keeps starting/running, back to the plot. Fuse box next, along with that bl**dy leaf spring farce. Link to comment Share on other sites More sharing options...
johny Posted May 30, 2019 Report Share Posted May 30, 2019 yes keep on knocking them down - remember its all part of the fun and one day will give you stories to bore the grandkids with🤣 Link to comment Share on other sites More sharing options...
Badwolf Posted May 30, 2019 Author Report Share Posted May 30, 2019 Fun....Grand-kids... you must be joking!!! -- Bah Humbug (sorry, wrong season) Link to comment Share on other sites More sharing options...
Colin Lindsay Posted May 30, 2019 Report Share Posted May 30, 2019 4 hours ago, Pete Lewis said: we converted a glass top from a vauxhall cheap to repair a worn old orig glass top ,, swapped the arms over Have some great NOS Delco pumps with incorrect arms from eBay, I'll do the same when I need to use one on a Triumph. 4 hours ago, Pete Lewis said: here we go sucking an blowing just dont get Doug involved with inlets and outlets or we drift wildly Do you suck the inlet and blow the outlet, or is it the other way round? Link to comment Share on other sites More sharing options...
Pete Lewis Posted May 30, 2019 Report Share Posted May 30, 2019 I prefer to put my finger over the outlet while pumping !!! Pete Link to comment Share on other sites More sharing options...
Badwolf Posted June 1, 2019 Author Report Share Posted June 1, 2019 Does anyone have a link for good quality auto cable. Something that is coloured with a trace colour that will also take a bit of current, not like the .5mm thinwall auto cable on fleabay? Link to comment Share on other sites More sharing options...
Anglefire Posted June 1, 2019 Report Share Posted June 1, 2019 Not sure about the trace colour but I’ve used this company for other stuff https://www.tlc-direct.co.uk/Main_Index/Cable_Index/Tri_Rated_Cable/index.html Link to comment Share on other sites More sharing options...
Anglefire Posted June 1, 2019 Report Share Posted June 1, 2019 Thought these do trace colours I don’t think it’s tri-rated https://www.12voltplanet.co.uk/news/bi-colour-cable-with-tracer-stripes-and-cable-by-the-reel.html Link to comment Share on other sites More sharing options...
Clive Posted June 2, 2019 Report Share Posted June 2, 2019 just used http://www.vehicle-wiring-products.eu/ as I had a loom "mishap". They sell both thinwall and "traditional" cables in virtually all colours and with traces (some cables are only available plain, but I managed to get exactly what I needed) Link to comment Share on other sites More sharing options...
Badwolf Posted June 2, 2019 Author Report Share Posted June 2, 2019 Thanks Mark. Can you explain tri-rated please. I am looking to get some lengths of cable to match the existing colours for when I do the fuse box. Especially for extra bits like a cigarette lighter socket, so I can identify in time to come. Thanks Clive - Got the fuse box from them through fleabay, never though to look at their other stuff (doh!!). Link to comment Share on other sites More sharing options...
Anglefire Posted June 2, 2019 Report Share Posted June 2, 2019 Tri-rated is to 3 different standards - used mostly in electrical cabinets because it is flexible and normally thin wall. So Clives link is probably just as good. Link to comment Share on other sites More sharing options...
Badwolf Posted June 2, 2019 Author Report Share Posted June 2, 2019 Thanks everyone. I noticed when fitting my headlight relays that the original earth (black) wire was a little thinner than the two feed wires. Earth = approx 2mm, feeds approx 2.5mm overall dia. Is there a technical reason for this and is there any point/advantage in replacing the earth with a thicker wire, while I am messing about with this? I am looking at using 2mm wire in everything that I upgrade, is this just overkill and, on the whole, would 1mm be as good. I can handle a soldering iron, but when it comes down to V=IR etc and working out loading, cable thickness, power requirements etc, not so good!! Link to comment Share on other sites More sharing options...
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