Luke Remon Posted December 25, 2019 Report Share Posted December 25, 2019 Hi everyone, I recently bought a Triumph Spitfire 1500 and had it rebuilt by a member of family who is more knowledgeable than I, but now its back at home it's having some teething issues. The first problem when I drove it back was the fuel pump, but that has since been replaced. Now the engine pulls well until around 3500 rpm when it bogs down and then when it eventually reaches 4200 rpm ( only in first mind), it accelerates like a rocket for the brief moment I keep my foot down. Shortly after the engine bogs there is a strong smell of petrol in the cabin. But the strange thing is that it revs up fine when in neutral and sometimes it won't even bog down when in gear which is really quite odd because then 20 seconds down the road it will start to bog again. I'm only 18, this is my first classic and also I don't have much money to throw at it for unnecessary parts so it would be really helpful if someone could help diagnose the issue. Thanks in advance, Luke Link to comment Share on other sites More sharing options...
Pete Lewis Posted December 25, 2019 Report Share Posted December 25, 2019 after any rebuild theres a good chance of the dreaded rubber slivers blocking the float needle valve and when full flow is asked it is restricted caused by fitting fuel hoses onto the metal pipes , they cut a small slice off the hose inside and they float about , , ths can get repetative if you keep removing just outof hospital so not up t speed and it christmas . ask away lots of clues and fun on here Pete Link to comment Share on other sites More sharing options...
Anglefire Posted December 25, 2019 Report Share Posted December 25, 2019 Fuel starvation as Pete alluded to Either the wrong pump is fitted (even if you can these days) or restriction in the fuel lines. Given it will accelerate for a short while it’s going to be fuel line related 95% sure. If they aren’t new, then I would fit R9 rubber in place - and get it from somewhere like the club shop as you know it will be the correct stuff and not fake stuff. Link to comment Share on other sites More sharing options...
Pete Lewis Posted December 25, 2019 Report Share Posted December 25, 2019 good idea on fuel pump the 1500 orig had a spacer replacement pumps need it removed and shorter studs fitted or packed with washers all due to the pump lever om 1500 is longer , fit a short reach pump and ....you get very little pump action if the spacer is left in place pete Link to comment Share on other sites More sharing options...
johny Posted December 25, 2019 Report Share Posted December 25, 2019 I think rather than the pump not giving enough it's more likely to be that the greater pressure it generates at higher revs is overcoming the carb float valve. This is causing the mixture to go very rich so the engine bogs plus the carb overflows which then gives the strong petrol smell.... Link to comment Share on other sites More sharing options...
Pete Lewis Posted December 26, 2019 Report Share Posted December 26, 2019 yes but the pressure is depenant on the pumps spring nothing to do with any rpm the spring gives a contant pressure regardless of what the engine is doing some replacement pumps have been found to give far more than the 2.5psi specified and yes overcome the float needle valve Pete Link to comment Share on other sites More sharing options...
Luke Remon Posted December 26, 2019 Author Report Share Posted December 26, 2019 As I said I fitted a new fuel pump from Rimmers, however the petrol smell was still around with the previous pump. Also it seems to bog more when the engine is hot, but I will change all the fuel lines. Many thanks, Luke Link to comment Share on other sites More sharing options...
Luke Remon Posted December 26, 2019 Author Report Share Posted December 26, 2019 If the pump is a problem should I fit an inline regulator in the fuel system? Link to comment Share on other sites More sharing options...
dannyb Posted December 26, 2019 Report Share Posted December 26, 2019 I had a couple of new mechanical pumps that put out different pressure at different times. One pump was putting out 9 lb pressure. The quality of the new pumps are questionable. since switching to electric pump with regulator I have had no problems in 8 years. Danny Link to comment Share on other sites More sharing options...
johny Posted December 26, 2019 Report Share Posted December 26, 2019 I know it can be frustrating Luke but don't be tempted to just throw money at this problem. If the bogging down and fuel smell are connected then the problem must be in the carb area when an excess of fuel occurs. As it did this with the previous pump that only leaves a float/needle valve problem. Possibly you have dirt or something in the float chamber that is intermittently stopping the valve from closing? Link to comment Share on other sites More sharing options...
Luke Remon Posted December 27, 2019 Author Report Share Posted December 27, 2019 I cleaned out the float chambers today and there was no dirt in them, they closed properly and they opened properly and there were no cracks in the float. Also the engine runs really poorly when its really warm and also really struggles when it has been idling for 10 seconds or more. This is only under load though- if I put the clutch down the engine revs up fine. Thanks again, Luke Link to comment Share on other sites More sharing options...
KevinR Posted December 27, 2019 Report Share Posted December 27, 2019 If the car still has standard points, condenser and coil ignition, check that the condenser hasn’t failed as revving properly under no load, but struggling when on load is a symptom of a failed condenser. Link to comment Share on other sites More sharing options...
Pete Lewis Posted December 27, 2019 Report Share Posted December 27, 2019 yes good call, often backed up by misfires and random back fires Pete Link to comment Share on other sites More sharing options...
johny Posted December 27, 2019 Report Share Posted December 27, 2019 It's the petrol smell that's mystifying but of course it and the poor running could be completely separate problems! That's the fun of old cars😉 Link to comment Share on other sites More sharing options...
KevinR Posted December 27, 2019 Report Share Posted December 27, 2019 As Johny has hinted at, don't assume there is a single fault that when fixed will cure the all the symptoms in one hit ! Link to comment Share on other sites More sharing options...
Luke Remon Posted December 27, 2019 Author Report Share Posted December 27, 2019 It's got electronic ignition on it Link to comment Share on other sites More sharing options...
Anglefire Posted December 27, 2019 Report Share Posted December 27, 2019 Put it back to points 😂 not uncommon for electronic ignition to fail either. Link to comment Share on other sites More sharing options...
Paul H Posted December 27, 2019 Report Share Posted December 27, 2019 What make of electronic ignition are you using ? Paul Link to comment Share on other sites More sharing options...
Nick Jones Posted December 27, 2019 Report Share Posted December 27, 2019 Is the choke fully returning? You need to check that both jets go back to their normal warm ruining position against the adjuster nuts when the choke is pushed in. My vote is over-fuelling. Possibly due to excess fuel pressure if the choke is working as it should Nick Link to comment Share on other sites More sharing options...
Luke Remon Posted December 27, 2019 Author Report Share Posted December 27, 2019 Accuspark ignition Also when it bogs if I pull the choke out it sorts it out and it runs better and revs further. It's also started to hunt at idle. When I get back I'm going to check the plugs so I'll update then. Link to comment Share on other sites More sharing options...
Luke Remon Posted December 28, 2019 Author Report Share Posted December 28, 2019 Right I've checked all the plugs and they're all white so I'm guessing carbs aren't tuned properly Link to comment Share on other sites More sharing options...
Luke Remon Posted December 28, 2019 Author Report Share Posted December 28, 2019 Hi all, I've been researching these symptoms all over the internet and I've found that it could be the wax stat jets that are in it. Apparently when the engines hot they cause too lean a mixture (which I saw from the plugs) and a very rough idle. So I may try some standard jets in it and see if that resolves the issue. Any other suggestions would be greatly appreciated however. Luke Link to comment Share on other sites More sharing options...
Dick Twitchen Posted December 28, 2019 Report Share Posted December 28, 2019 Luke, Suggest you get yourself along to the East Sussex area meeting (not all TSSC members are regular forum users) and say hi to them, all being well you will be overwhelmed with practical help that will/may save you £££. Details are in the Area Contacts on the home page and it looks like they meet not far from Bexhill. Dick Link to comment Share on other sites More sharing options...
johny Posted December 28, 2019 Report Share Posted December 28, 2019 A lean mixture can give the symptoms you describe (well except for the fuel smell but that could be something else) and might just be the carb setting. I don't know how it's done on your type of carb but it sounds worth checking.... Link to comment Share on other sites More sharing options...
Anglefire Posted December 28, 2019 Report Share Posted December 28, 2019 If you do have waxstats on your carbs - and the 1500 did as far as I know (Mine did!) then you can remove them with either a kit of bits to convert to conventional jets or use a couple of pennies. Instructions on how to do the latter are here http://ekalakal.com/gallery/albums/userpics/SU_Waxstat_Jet_Tube_Conversion.pdf Link to comment Share on other sites More sharing options...
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