Hi - I wonder if anyone can offer any advice regarding a problem with a Series 2a 1970 2.5 petrol. The problem: when the vehicle is on the level it starts without any problem, revs and idles well. When you drive up an incline its cutting out and just before it does cut out, emits a puff of dark smoke from the exhaust, then its hard to restart, until you can get it back onto level ground. So far its had the following replaced - piston rings, valve seals, valves, spark plugs, head gasket, fuel pump, fuel lines from tank to pump, distributor, carburettor, coil. Any suggestions/advice on what would be causing the problem (which Im guessing prevents fuel uptake when going uphill) and how to resolve it would be really appreciated. Thank you.

 

My guess is too much fuel, not fuel starvation (with the observed black smoke). The first thing I would suspect is the carb float level is too high. When on an incline it may spill directly into the intake. Please keep us posted on your progress (or dead ends as well) with this issue.

 

Oh, I just noticed you replaced the carb. Did it do the same thing with the old carb?

 

Hi - yes that was one of the reasons for replacing. Someone has suggested adjusting the float in the carb but would this need to be done on a new carb? If it was happening with the old one as well what else could be causing the issue. Thanks for responding by the way.

 

Yes. Float adjustment is really an installation and 'tuning' function just like setting idle and mixture screws, not something that gets cured by bolting on a new carburetor. You might get a new off-the-shelf carburetor that has the float set to the right level, but that really would be more luck than anything.

 

Hi - thank you for responding. If it’s the float, why would it just suddenly start happening on the old carburettor? Presuming the floats dont slip?

 

Hi all. Please bear with me as Im not the owner of the vehicle - it belongs to someone who lives abroad so Im relaying messages and asking questions! Just had a phone call to say a mechanic has been working on the vehicle and this is the latest. He says it’s not a carburettor issue. When it’s on the level it works and drives just fine. When going up an incline it cuts out and puffs dark smoke. This doesn’t happen when it’s on the leve. If you take off the line to the carburettor and pump by hand, everything is ok but when the line goes on it’s being starved of fuel. When it comes back onto the level it’s fine. Sorry to be a pain with this.

 

Fuel, air, spark. That's it.

​​​As @Harvlr noted, puff of smoke sounds like excess/unburned fuel. Fuel has to be pumped to carb (tank pickup, lines, pump). When it gets to carb, it has to get metered with air. Metering is done with jets and butterflies. Fuel metering is done from bowl... which is kept full by float. That's it.

On a hill, not much changes... except pickup angle in tank. Is it out of gas? And carburetor bowl level. Is it getting too much fuel that then spills un-metered and un-mixed with air into the engine?

 

Seems 2.25 engine was replaced with a 2.5? check ignition wiring by Hot Wire ignition and bypassing all stock wiring , if issues is resolved then look for the stock wiring grounding out as vehicle encounters incline, engine swaps can chew wiring by accident.