Stumbling/Stalling Out

[Timo04]

Greetings,

Yesterday when driving home from work on the freeway the Scorpion (a completely OEM car, ie no mods, US spec) ran flawlessly as it has all summer. However aftering exiting the free way and driving on "surface" streets and during excellaration, the engine stumbled and quit running. I managed to coast the car down an overpass and then hit the starter motor with the clutch pedal depressed and the car started up and ran roughly for about 1min or so moving me along about a 1/4 mile and then the same thing happened all over again; mis-fire, stalling re-start. The engine is not easy to re-start but it does fire back up eventually after several attempts. Then finally upon one of the re-starts the car started right up and run perfect/smoothly like there was never a problem for several miles (at least for a while) until it stalled out once again. Also I want to add that at times the engine idles very smoothly at other times it idles roughly, and sometimes there is slight stack fire when depressing the gas pedal.

I have driven the car almost 1k miles, back and forth to work and mostly on freeways, since early June and all this time it has run really perfectly until just today.Could it be the fuel pump going out? dirty carb jets? Somthing to do with the auto choke? The car is timed correctly and just passed smog in May. All suggestions and advice as to what the cause could of this "stumbling" are very welcome. Have a great weekend and thanks in advance!

[Darren]

Hi Timo,

One of those difficult things to trace that takes time - you gotta start with the fuel lines and check them through - fit a fuel filter if you don't have one already- check spark plug colour for ideas on where the problem lies. I'm sure you'll get a rake of different ideas here mate - but certainly ( to me at least!;o)) ) sounds like fueling, so you got to check all in that circuit - pipes, pump, relays etc

Hope you get it sorted!

Darren

[Timo04]

Hi Darren,

Thanks for the tips and advice! I will post the solution one I discover it. Have a good one.

[A1.6HPE]

Hello Timo04,
I agree with Darren, sounds like fuel starvation. Change whatever you can - fuel pump (is it mechanical or electrical - if electrical check the wiring), filter element could be collapsing if old (fuel filter). If no filter, check the one in the carburettor (brass hex underneath the fuel pipe connections). Original rubber hoses could have perished internally so that a flap of rubber occasionaly blocks the flow.

Leo

[Geoff T]

Timo,
My two cents worth............
The first place I would check is the carb! Sounds very much like you have a bit of grass or something floating around inside the carb. Webers are very prone to this regardless of how many filters you have on the fuel system!
If it was running fine then suddenly played up, this is where I would start.
Remove all the idle, main and air jets and blow them out with compressed air. If you can, do the same with the jet holes. Cover the carb with a rag first as gas will go everywhere!
If you are careful pulling the jets out, you may even find the bit of debris stuck in one of the jets. I have numerous times, especially in the idle jet. If the engine refuses to idle but will run at higher rpm, you definately have a blocked jet. If your fuel pump fails it will either refuse to start altogether, or will die at higher rpm and recover again as the revs fall. The fuel pump can't keep enough fuel up to the carb.

Geoff T.
Series 2 Montecarlo.