fuel supply problem
Turbo Mini Forums

im trying to start the engine for the first time, but it doesnt want to know. i have fuel to the carb ok, at around 5psi, there is fuel in the fuel chamber, but it doesnt seem to go anywhere from there, the plugs dont smell of petrol at all, i know there arent ay blockages in the pipe that the jet holder is located around as i blew through it, any ideas why it isnt reaching the head? cheers

A-series power! 1972|1310|T3 turbo|Omega pistons|Cantre main strap|Orange clutch diaphragm|AP race plate|Comp pressure plate|Lightened steel flywheel|13-row oil cooler|Vernier duplex timing gear|Phase 2 Piper cam|Green air filter|Hi boost carb needle/spring|2"Stainless exhaust|3"Play mini stainless rear box|Jack Knight s/c 4spd gearbox|Jack Knight s/c drop gears|Silicon coolant hoses|Lumenition HT leads|GAZ lowered height shocks all round|Steel flip-front|Rear safety devices cage|Group 5 arches|6x12 deep dish Minilites|Surf blue/Old english white|

blocked main jet?

stuck piston?

alex

AlexF

ive had the jet out and cleaned it up and that didnt seem to sort it, im thinking of taking off the vacumm pipe on the inlet manifold to see if i can see fuel run in the inlet manifold, do you think (if there was any fuel there) if you would be able to see if flow?

A-series power! 1972|1310|T3 turbo|Omega pistons|Cantre main strap|Orange clutch diaphragm|AP race plate|Comp pressure plate|Lightened steel flywheel|13-row oil cooler|Vernier duplex timing gear|Phase 2 Piper cam|Green air filter|Hi boost carb needle/spring|2"Stainless exhaust|3"Play mini stainless rear box|Jack Knight s/c 4spd gearbox|Jack Knight s/c drop gears|Silicon coolant hoses|Lumenition HT leads|GAZ lowered height shocks all round|Steel flip-front|Rear safety devices cage|Group 5 arches|6x12 deep dish Minilites|Surf blue/Old english white|

The SU is so simple, there are only a few things that can cause problems like this.
no air flowing over the bridge (venturi)
Needle closing off the jet tube
or float chamber open to atmosphere.

So, in reverse order - have you sealed off the anti-run on pipe from the carb? Clamp the hose with a set of mole grips just to be double sure.

Needle closing off the jet... Easy to check by removign the piston assy. The piston should move (check it aint seized). Check the needle holder is flush with the bottom of the piston, and (still with the piston assy removed) check the height of the jet against the top of the bridge in the carb body. As a guide, the jet should be 3mm or so lower than the bridge. This height is altered with the mixture screw.

No air flowing over the bridge... hmmm tricky one! A HUGE manifold leak, badly timed in cam, or rockers wound right up such that the valves were open all the time - as you can see, all stuff that would be obvious after a compression test, or just the sound of cranking the engine over...


I really can't think of anything more! oh - just make sure you have oil pressure before firing it up, a lack of oil will kill a turbo in seconds...

Edited by turbodave16v on 23rd Dec, 2003.

Cheers for the pointers dave, trying to answer all of them. i have got oil pressure, as i connected up the pressure gauge and just cranked the engine over without the plugs in so it turned freely, got good oil pressure, more than 50psi.

when you talk about the anti run on pipe, is that the one that loops back on the carb from the mounting flange to the body? if so, i have the pipe connected.

i could see by taking off the vac connection on the inlet manifold that there was fuel in there, so i am assuming it is reaching the bores as i could smell slight petrol on the plugs. i am quite confident that the cam is timed in ok as the guy who did it also did my mates and he also races in the mighty mini series (Paul Inch)

the piston moves freely so that is not seized. i have also checked that all of the valves are closed, as there is the tolerance gap that there should be between the rocker tip and the top of the valve, so again i am confident that all of the valves are seating as they should.

the only other thing is that i might have the ignition timing out, i did that once before and had it 180deg out. i can check this by making sure piston.1 is in tdc and that the rotor arm is about to fire on lead one yes?

only thing that concerns me is that i can hear sparking, while the engine is cranking over, the same sound as when i take the plug out to make sure that it is sparking. also, when the plug does spark, it doesnt spark once, it sparks 2 times very quickly as if it looks like one spark but you can see its two if you look close, does this sound normal? lol

A-series power! 1972|1310|T3 turbo|Omega pistons|Cantre main strap|Orange clutch diaphragm|AP race plate|Comp pressure plate|Lightened steel flywheel|13-row oil cooler|Vernier duplex timing gear|Phase 2 Piper cam|Green air filter|Hi boost carb needle/spring|2"Stainless exhaust|3"Play mini stainless rear box|Jack Knight s/c 4spd gearbox|Jack Knight s/c drop gears|Silicon coolant hoses|Lumenition HT leads|GAZ lowered height shocks all round|Steel flip-front|Rear safety devices cage|Group 5 arches|6x12 deep dish Minilites|Surf blue/Old english white|

The anti run on pipe is the one on the side of the carb near the fuel in pipe.

To time the engine roughly you have the right idea, but there are 2 different tdc one on the compression stroke and one on the stroke to push the exhaust gas out. You need tdc on the compression stroke (basicaly watch the inlet valve, once it closes and then you reach tdc you have the right position to fire on 1, if you are turning the engine over the correct way that is, (i have made that error!)

The anti-run on pipe is the one around 3/4" forwards of the fuel inlet pipe on the same side and same orientation. If this is not sealed, you will never start the engine!

Just as sumpnut said, turn the engine over (easiest way is to jack up one wheel, put it into 4th, and turn the wheel to turn the engine!)
Once you see the inlet valve on no.1 shut (second valve from the 'stat) then tweak the engine until the crank is at TDC (valve shuts 30-60 degrees after TDC depending on the cam). you can use the pointers on the pulley, or remove the spark plug, and feel for exact TDC with a (clean) screwdriver touching the top of the piston.
Once at TDC, remove the dizzy cap, loosen the dizzy clamp and rotate the dizzy such that the rotor arm is pointing towards one of the contacts when you re-fit the cap. This point on the cap is now no.1 plug lead. Re-fit the cap.

Noting the rotation of the rotor arm as you crank the engine over (i always forget if it is CW or ACW!!! someone tell me!!!) fit the other leads in the order 1-3-4-2 from your reference lead (no.1)

Now, get someone to crank the engine over, whilst you rotate the dizzy with your hand. It should crank into life if all is ok. Next, advance the dizzy until the revs just start to drop, and that is close enough until you find a strobe light or Rolling road.

Edited by turbodave16v on 24th Dec, 2003.

thanks lads, yeah i have a timing gun. i believe my engine to be from the mk1 metro turbo which, i think already has the run on pipe blanked off as i only have two connections on the carb, the fuel in, and that link pipe that loops around from the side of the carb to the flange of the carb. i'll have another go today at timing it in, but i dont think i will gain much as i have noticed a water leak between the head and the block by the engine ident plate! which means i think the head will have to come off and be skimmed! destined not to have this car on the road

A-series power! 1972|1310|T3 turbo|Omega pistons|Cantre main strap|Orange clutch diaphragm|AP race plate|Comp pressure plate|Lightened steel flywheel|13-row oil cooler|Vernier duplex timing gear|Phase 2 Piper cam|Green air filter|Hi boost carb needle/spring|2"Stainless exhaust|3"Play mini stainless rear box|Jack Knight s/c 4spd gearbox|Jack Knight s/c drop gears|Silicon coolant hoses|Lumenition HT leads|GAZ lowered height shocks all round|Steel flip-front|Rear safety devices cage|Group 5 arches|6x12 deep dish Minilites|Surf blue/Old english white|

What was te fault in the end with your crank / flywheel?

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