Alfie

Don't have the waxstats fitted. One of the many things Ive done was to run the fuel line around the rear of the block on top of the bulkhead which made no difference so next move will be to strip the carbs and check them over. Any body have the correct the height the fixed jet is below the carb body bridge.

The SU electronic fuel pump has arrived, fitted beside the fuel tank in cool air. Ran the engine until upto operating temp then swithched off for 5 mins and trued to start again but no luck had to lift the bonnet and leave for 15 mins to cool down, the engine then started after a littl cranking over. So my thought is to pull the carbs off and check over the float height and also the fixed jet height in relation to the carb body, both carbs were overhauled so there may be something i have missed or set incorrectly when overhauling them. Does any body know what the measurement is between the top of the fixed jet and carb bridge?  

I am wondering if maybe there is a pipe in the wrong place or missing, has anybody got a photo of there MK3 GT6 engine carburetor side so i can compare.

With what you have said JohnD regards no pressure build up in float chambers, i need to re create the hot start issue then drop the carb fuel bowls to see if there is fuel in the float chambers which should be the case if the float needle valve is closed so causing the build up of fuel vapor pressure in the carb fuel supply pipe.

Thanks for all the replies guys. Ive fitted electronic ignition and replaced the rotor arm with one from the Dizzy doctor online. Today i took the car for a good hours drive parked up for 10 mins with the bonnet closed then tried to start the engine with no joy, even after trying the full throttle scenario. Lifted the bonnet to check the glass filter bowl on the King fuel regulator/filter and surprise surprise the bowl was totally empty tried to manually pump fuel with the lever on the mechanical pump but no resistance in the lever so cranked the engine over still no fuel being supplied to the glass bowl so slackened one of the fuel rubber hose clip's on the front carb and slid the rubber fuel pipe off the copper pipe at which point a pressure hiss could be heard with a strong smell of petrol, replaced the rubber pipe , cranked the engine and the glass bowl started to fill with fuel then the engine started. There is never a fuel issue when the engine is running, no starvation under heavy throttle or poor tick over how ever if the engine is ticking over for a number of minutes at stand still and the twin electric cooling fans kick in the revs drop due to alternator load then after a few minutes the engine stalls, lifting the bonnet shows no fuel in the King regulator glass bowl. This all points to fuel vaporization which must be creating an air lock in the fuel supply pipe that the manually pump can not overcome so fuel starvation occurs. What i need to find out is the air lock in the new mechanical pump which would indicate the no resistance in the pump manually lever i felt when i tried to manually prime the system or is it in the pipe from the mechanical pump to the carbs either way it points to heat build up in the fuel pump transmitted from the engine block plus the hot air being blown over the engine bay by the electric cooling fans. If this is the case how can i overcome this, would fitting an electric fuel pump be the answer and also why would triumph design a fuel system that was unreliable to say the least OR is it modern fuels that have made the problem worse.    

The fuel line has been re routed along the bulk head in rubber pipe clipped to the bulk head and any copper lines have been covered in a heat reflective sleeve. There is a stainless heat shield behind the carbs between the carbs and exhaust manifold. The one area that has direct contact with the block is the mechanical fuel pump, ive changed this (metal top not a glass bowl top) to eliminate it but now are starting to think an electric fuel pump may be the way to go. Ive read the electric fuel pump was chosen when fuel vaporization caused the engine to cut out in hot weather not poor hot starting so still not convinced the elec pump is the way to go. I seem to be making more questions than answers so far. The dash pot oil is general engine oil, why do you ask Any advice guys from some body who has manged to cure a poor hot starting Gt6 engine.

Been trying various fixes to get my Mk3 gt6 engine to start easier when hot, at the minute i have to floor the throttle with a little choke and keep cranking till it fires up this can take 10 to 20 seconds which i think is to long. The carbs have been fully overhauled, engine has new rings with honed bores with hardened valve seats for unleaded. Also fitted new dizzy arm from dizzy doctor online in case it was faulty when hot as ive read there was a batch of dud ones. Electronic dizzy fitted from H&H. When the engine is cold it start first turn on the choke so my thought is its running lean plus the possibility of fuel vaporization, this i have tried to overcome by insulating the copper fuel pipe around the carbs plus Ive fitted a stainless heat shield and wrapped the exhaust manifold and exhaust system in heat wrap to cut down on heat radiation, once the engine does fire up the choke is pushed home and it ticks over happily, the exhaust fumes smells rich to me which contradicts the lean theory so i am now at a loss as to what to do next. The engine pops when on throttle over run which indicates its running lean, i adjusted the jets to enrich which took the popping away on throttle over run but still had the hot start issue. This problem occurs even if the engine is stopped for 5 mins for say a refuel at a petrol station, just the other day i had to push the car away from the pumps and lift the bonnet to cool the engine down for 10 mins at which point the engine started. Any advice welcome, and just in case it helps ive fitted a fuel regulator and gauge then tried various fuel pressures from 2 psi to 8 psi which makes no difference to the hot starting problem.

Ok so i have wrapped the exhaust manifold and the engine still refuses to start when hot. I have at the moment sainsubury's unleaded petrol in the tank which i assume contains ethanol so my next question is anybody using a standard unleaded mix that contains either 5% or 10% ethanol without any problems OR do you tend to run on one of the main suppliers super unleaded mix which i have been informed is ethanol free at the moment. Ive not ran the car on the road so do not have any previous experience with this engine.

The fuel line is re routed to the back of the block which is close to No 6 cylinder exh manifold pipe which is where i think the problem may be, also dusz has pointed out there should be thermal spacer's between the carbs and manifold is a thermal gasket ok or do you mean a thicker block type insulator.

I have a ally heat shield fitted covering the carb float chambers etc maybe i need to look at a shield between the exhaust manifold and intake manifold. Is a none starter when hot fuel vaporization a common problem with the GT6.

The reason i am thinking of fitting the wrap is to eliminate a heat source which i think is possibly causing fuel to vaporize in the intake manifold when the engine is up to temperature. The problem i have is if the engine is switched off once up to temperature then i try to re start it won't i have to leave it 30 mins or so before it will start so i thought by wrapping the manifold it would cool the engine bay down.

Looking to wrap a stainless manifold in exhaust wrap. Can any body recommend a good brand and what length will i require for a six branch manifold plus is 1 or 2 inch better.

Ok i think i may of found the problem, i think the fuel is vaporizing due to the heat build up in the intake manifold. Ive got a stainless manifold which i am going to wrap in heat tape to see if that cures the none starting problem. Today after the engine was stopped then tried to restart unsuccessfully i let the engine cool for half an hour at which point it started, i removed the plugs after the attempted restart to check if they were dry which they were so no fuel getting to the cylinders when hot.

Thanks Guys, checked the float chambers for deb re etc but nothing found so turned the regulator down on the filter king however the engine still will not start when hot but is not flooding now. The symptoms are engine starts with choke when cold and idles, pulls away ok but once up to temperature with the electric cooling fans working and i pull away then stop lifting off the throttle the engines dies and wont start again, if i gently touch the throttle the engine does not stall. There's a smell of petrol out of the exhaust when turning the engine over after it stalls which suggests cylinders have a supply of petrol. The carbs have been refurbished with a full build kit including butterfly valves, the ignition is a brand new electronic system with new plugs leads and dizzy, the engine has been fully overhauled also. One thing ive not done is check the fuel mixture with a gunson colour tune. Any advice as to what may be the problem.  

Been having problems with a pair of overhauled 150 strombergs, engine starts ok with the choke and warms up but if the engine stalls with the engine hot and you try to restart again petrol pours out of the front carb from a hole on the filter mount flange face. Ive included a photo showing the hole the petrol pours out of. Ive also fitted a new mechanical fuel pump and a filter king. All petrol pipes are brand new. Can any one suggest what the problem is. One thought is to reduce the fuel pressure by the filter king but my line of thought is that if it is a high fuel pressure then why only one carb flooding.