hi guys i need your help ive just bought a 1.4 340 and it will not tickover it has new plugs leads cap rotor arm i also did a compresion test
it seems like fuel starvation it will run ok on choke but as soon as the choke is off its like its ran out of petrol
i have stripped the fuel pump that was ok and changed the carb but it has made no differance
please guys any ideas i dont want to see another 340 die and go to the great scrapyard in the sky
any way merry christmas and happy new year to you all
If it's ok on choke, it must be getting fuel I'd say. If it dies off choke, I'd say its an air related problem, have you checked the carb top is secured to the carb body (needs to be torqued correctly, else you'll get more problems!)
Actually, this happened on my 1.4 several times thinking about it, check your spaceman tube first, I reckon its cracked. Its the 2" ish diameter ali tubing between the exhaust manifold sheild and the airbox, that really screwed mine up when there was no hot air feed. Don't get new stuff from factors, its a lot thinner, and crackes within 6months with the way the 1.4 manifold moves. Not sure if Volvo still make it, but worth a go.
Chris_C wrote:If it's ok on choke, it must be getting fuel I'd say. If it dies off choke, I'd say its an air related problem, have you checked the carb top is secured to the carb body (needs to be torqued correctly, else you'll get more problems!)
Actually, this happened on my 1.4 several times thinking about it, check your spaceman tube first, I reckon its cracked. Its the 2" ish diameter ali tubing between the exhaust manifold sheild and the airbox, that really screwed mine up when there was no hot air feed. Don't get new stuff from factors, its a lot thinner, and crackes within 6months with the way the 1.4 manifold moves. Not sure if Volvo still make it, but worth a go.
the top of the carb is the first thing i looked at its all tight
how would i look for air leaks around the maifold or shall i just change the gasket
spray round all the joints with the engine idling as best it can, with Wd-40 or an unlit blowlamp, when you find an air leak, the idle will suddenly improve.
I would say there's an air leak from somewhere, check the 4 bolts at the base of the carb for tightness, they should be fairly tight, but don't hang off them otherwise you might crack the gaskets
The hot air hose is important at this time of year, with the cold weather. I would have said its a worn carb, but then you say you changed it over already
My car doesnt have a hot air feed from that exhaust shield at all so its definately not that. If it will only run on the choke i say its more likely to be fuel mixture or even check the throttle adjustment screw to see if it worked loose. Other than the idle does the car run fine? Try holding the throtlle down a bit and taking the choke off, if it stays running its the throttle adjustment screw!!
Adam
Good check, but I don't agree on the warm air feed. Both my carb cars have stopped idling with the spaceman tube cracked, and thats in the summer as well. Surely if the carb is tuned for the hot air feed, then the mixture will be screwed if you loose it, with the relative air densitys?
Under what condition have they been playing up with it cracked? Exactly what does the engine do? It could be a case the valve is not working and constantly directing hot air maybe?
They'd run fine beforehand, and then the car would just not idle when you take it off choke. I got to the stage that I sussed this was happening after a time, so I wrapped the pipe with gaffer tape to get me home. As soon as the crack is covered, the car worked perfectly again (to the stage I left one of my tubes gaffered for 6months...)
The one I have on Fake at the moment is fibreglassed, as I can't get any good tube to replace the orig stuff. Steve was with me the last time it went as I was on a rally, so he can testify I'm not making it up! Literally looses nearly all power, and unless you keep some throttle on it will stall.
If that is the case the engine will have been up to temerature. When the engine is up to temerature the air flow should only be coming from the cold air tube and not the hot air.
I would suggest jamming the flap so it only ffes in cold air - if yours is not working you will be loosinbg a few BHP and couple of MPG as well.
When you do it you will probably need to tweak the fueling for the cold air.
Are the flappy things known to die? I've just looked at Haynes way of checking it... I'll put the hair dryer onto both Kar and Fake when I get a min this week!
now thats interesting. I didnt realise it could have such an impact but the affect of sucking in warm air to a warm engine /carb does make sense.
My understanding is the thermostat in the air intake closes once the engine warms up. From haynes it seems the air intake is a mixture of cold and warm air as the valve allows a mixture of the two up to a max of 100% warm or 100% cold. Presumably the thermostat uses the ambient air temp in the engine bay.
So, if the system is stuck on warm air only, the carb mixture will go out of acceptable range once the engine warms up, too little air entering the carb ( volume unchanged but density lower ).
Interesting since Michol's car ( the guy who owns the non idling 340 with a cross threaded spark plug ) runs worse at it warms up.
I think I'll add this to the list of thing to check!
interestingly, my 240 ( lives in a garage and gets started, exercised round the yard and put back ) also have enver idled well from day one. Admittedly, this car hasnt had lots of time spend on it apart from coolant changes and oil changes but the warm / cold air intake hose is disconnected and has holes in it.
If this air intake temp has such an impact, that might explain why this 240 always needs a little choke to make it idle ok.
Chris, you;re car also needs a little choke?
Michols car, worse running to the point it only barely idles on full throttle once warm. I'll add the air intake thermo to the lists of check but I wonder if it were jammed on warm intake only would it be able to cause such poor running as this?
this would mean therefore the air intake temp to the carb is kept within a narrow range.... wonder what that is?
would be interesting to do some datalogging on that with three electric thermometers........
