Conking out! [Archive] - SaabCentral Forums

: Conking out!


heavy_t
29th March 2003, 08:08 AM
Recently the beast has started to lose all power at the most innapropriate times. This happenned earlier when i was on a roundabout. Basically the engine just seems to almost die and I have to rev it hard to get it to kind of "pick up" again. This problem tends to only happen when the car has been driven at full temp, then parked up for 10 minutes or so and then driven again.

My feeling was that it could be vapour lock as it also needs a fair bit of cranking when starting from hot. I've wrapped some foil round the fuel line so I hope that will help. I've just had it serviced, new plugs, air filter, points checked and cleaned etc. so I don't suspect any of that.

anyone got any ideas?

thanks

Tom

TFatC
29th March 2003, 08:35 AM
Almost certainly vapour lock T. This new fangled unleaded is more prone to it than the old 4 star, had the same problem with the P6 and re-routed the fuel line away from the engine as much as possible. Foil may help, but some proper asbestos lagging or glass lagging if you cannot get the asbestos would be better.

kemosaabey
29th March 2003, 05:12 PM
I had a similar problem - turned out the float level was too high. I also fitted a new needle valve for good measure. But yes the unleaded fuel doesn't help matters..

I think saab recongnised it as a problem as later models had a return line from the carb so fuel was always circulating, and an anti run-on valve was fitted too.

kevitree
30th March 2003, 05:18 AM
Certainly sounds the vapour trap problem

If memory serves me correctly there is a Saab Mod to cure this

Memory being what it is I think its something like this....

After cars being driven and parked when hot and then hot day with sun beating on car(Bonnet) fuel vapourises from carburettor lines. Causing the car to start normal but on driving a short distance (in my experiences even a mile or so) fuel starvation occours causing spluttering and stalling

Saab did a pipe and fuel evaporator modification kit at the time! although I dont know if its still available.(I may have the info buried somewhere if you need it)

heavy_t
30th March 2003, 06:08 AM
Thanks kevitree - I might have to give the good old Saab Sanctuary a call.....

heavy_t
30th March 2003, 03:51 PM
Thanks for the advice everyone. It's been running terrible today in the hot weather. Basically was running too hot (slightly above N) around town and conked out on me twice, even though I hadn't parked up and left it at all..... When it dies it doesn't really splutter or cough, it just literally stops running, sometimes you can just about catch it and rev it back into life. I set the air filter adjuster back to the summer setting but it's still running just as hot, not dying out so much but is a bit spluttery and has a real flat spot when accelerating. Really frustrating this problem.....

Maybe the answer is to run it in summer mode and adjust the brass screw under the carb to make the mixture slightly richer (do you screw it in or out :-?? :o ) - I think I'll tape the fuel line to the top of the air filter just to get it away from the engine a little too....

I hope it makes it to the Kodak meet 'cos I want to take advantage of the Krypton tuning.....

kemosaabey
30th March 2003, 04:07 PM
To richen the carb turn the nut clockwise (looking from above).

Welshwizard was having similar problems and I think the cause was his timing was out...

heavy_t
1st April 2003, 11:06 AM
I called the old fella at Saab Sanctuary and got some free advice. He didn't follow the vapour lock theory (now I'm more confused) - I've tried re-setting the points and have set the gap to 0.015 (inches, AC Delco) so will see how this goes. This is what he reckoned, he thought the point gap may have closed.

Might try running U/L instead of LRP also as my car is actually intended to run on 95RON. It's cheaper too!!!

WelshWizard
1st April 2003, 03:02 PM
Yes, the timing was out on mine but the symptoms on heavy's car sound different to mine. What didn't help me was a heavy handed Welshman using the 'let's prod a screwdriver in there and see what that does' method while losing the screw that holds the condenser on the dizzy!! :roll:

Mine can run on 95 UL but is certainly happier using LRP and the occasional dose of lead replacement juice and redex.