Thread: Hot engine won't start

Could be several things but these two spring to mind.

1. Running rich will cause difficult starting when hot and unburnt fuel will explode in the muffler on an over-run. Might be worth checking the carburettor but I am unfamiliar with the Solex (if this is what you have), so can't offer any specific advice. Make sure that the choke butterfly opens fully and isn't being caught by a fouled linkage, or frayed cable.

2. Weak spark from coil. Substitute a known good one when it plays-up and see if that improves things. In the meantime give the ignition system a thorough overhaul.

Cheers Charlie

Points closing up?
Fuel in bowl vapourising?
Payback for neglect?

Vapour lock

dave

After a long run ,take a spark plug out and observe what colour it is ..if it's a dark sooty black.. your running rich ... also look at the exhaust pipe end and check for black sooty colour ..it should be a greyish colour .

It could be petrol starvation too .. you said it started with some choke .. a clue there ..

I agree with the comment.. do a thorough check of the ignition system and put a new coil in .. makes a big difference. A weak spark will cause inefficient burning of the fuel ... this can lead to fouled plugs too . The condenser is a off the shelf item at super crap auto .

Mike

Thanks for your replies everyone... except Scouse <_<.... ,
So I need to check the plug condition, the points gap, butterfly opening, replace the coil and condenser (brand/ part no. at SuperCheap?), 'overhaul' the ignition (getting hazy here...) and try adjusting the mixture.

What is 'vapour lock' is that the same as "Fuel in bowl vapourising" and how do I fix it if it's happening?

the greyish colour of the pipe is no longer as good an indicator as it used to be now that we dont have lead in the fuel...

try hand priming the carby prior to starting it or giving it a sniff of areostart to fling it over and let the engine prime itself up.

it might also be a points thing and the quickest and easiest way to prove or disprove that one is to put a test plug straight off of the coil and place it somewhere you can see it then fire it over if it sparks nicely then you know it s a fuel issue and providing it was a warmish day Id suggest a vapour lock or all the fuel evaporating out of the carby.

Originally Posted by Blknight.aus

the greyish colour of the pipe is no longer as good an indicator as it used to be now that we dont have lead in the fuel...

try hand priming the carby prior to starting it or giving it a sniff of areostart to fling it over and let the engine prime itself up.


This is a series 1 with an electric pump - no priming! but listen to the pump - no clicks, find out why (sick pump or wiring) - clicks do not stop; either flooding (new needle and seat or perforated float), or the pump is pumping vapour, probably due to a partly blocked strainer on the tank pickup or on the inlet to the pump or (unlikely) the fuel line is too close to the exhaust - from memory it is nowhere near it).

it might also be a points thing and the quickest and easiest way to prove or disprove that one is to put a test plug straight off of the coil and place it somewhere you can see it then fire it over if it sparks nicely then you know it s a fuel issue and providing it was a warmish day Id suggest a vapour lock or all the fuel evaporating out of the carby.

My guess is that it is a fuel issue as indicated, but a sick coil or other ignition component is possible (coils are the most likely to be heat sensitive)

John

slightly different but near enough to the same.

a vapour lock is where the fuel in the fuel line evaporates. the kicker is this.

as the pump "sucks" on the fuel line the pressure lowers, as the pressure lowers so does the vaporising point of the fuel. when the 2 get close enough the fuel in the line evaporates faster than the pump can shift it so you dont get any fuel just vapour hitting the carby.

Its a bigger problem on mechanical pumped engines as you either have to get out and hand prime OR wind the engine on the starter to get it to lift fuel to the carby. On an electric pumped engine just wait 10 minutes and try again, (treat it the same as below) the first order of the day on the preventative measure side is to make the suction line as short as possable, move the pump if you can and preferabley put it somewhere where there will be airflow over it when the vehicle is stopped

the fuel evaporating out of the carby bowl is simply a case of the residual heat in the engine causing the fuel in the carby to evaporate, cranking the engine over will usually overcome this as the fuel in the line should still be cool enough to not vaporise so the carby will fill up fairly quickly. If you have an electric fuel pump its just a case of turning the ignition on and waiting 15-20 seconds prior to trying to start the engine, usually you will hear the pump ticking or whirring away and when the carby reaches the correct fuel level the needle and seat closes, the fuel pressure in the line rises and the pump slows down.