Cuts out while stop

[79rolla]

Hey guys and girls. Just wondering if any one has any idea as to why my 79 ke55 shuts off under braking. Its under moderate to hard braking it cuts out. Light braking its fine and doesnt cut out. But moderate to hard braking it does. Doesn't matter if your on the clutch or not. It cuts out. Its done this with multiple Carby's now. Good and bad ones. But i don't know what it could be so would like some help on finding the problem. It is also a pain to restart. It will just sit there fast winding. It will take about 5 pumps of the pedal to restart if not more.

 

 

Cheers 79rolla 

Edited Tuesday at 09:48 AM by 79rolla

[altezzaclub]

Does it have the electrical fuel cut-out on the side of the carbie that the later ones did? Maybe that was KE70 only.

Is it easy to start otherwise, cold or hot?

Do you think it still has the same amount of fuel in the bowl when it stops?? So it shouldn't need a choke, or pumping the accelerator, it should start on idle.

Will it start just holding the pedal down about 10-20%?

Check the coil and distributor wiring, I've seen a broken coil wire that sat on the terminal until you braked hard, whereupon it swayed away and only went back to the coil as the motor shook from cranking.

[Banjo]

Could well be either fuel starvation, or an electrical issue, like Altezzaclub suggested ?  I'm going to suggest something slightly different. The olde mechanical fuel pump, on the engine, unfortunately gets little attention. Again unfortunately; they suck, fuel all the way up from the tank. You only need a small hole in the diaphragm; or crack in the fuel line; to have them give up. My initial suggestion, is to ensure you have fuel feed to the carby.  Take all four spark plugs out & disconnect the power feed to the ignition coil. Unscrew; the fuel inlet pipe to the carby, slightly. Only do this test, with a cold engine. Crank the engine, & see if any fuel comes out at the carby. If not, or very little, then remove the fuel tank cap, & try again. If removing the fuel cap results in fuel now coming out; then it could be the tank breather is blocked. If still no joy; then it is time to remove the fuel pump, & check the diaphragm for holes or cracks.  If still no obvious reason, then I suggest taking the inlet line to the fuel pump off, & blowing back to the tank, with the fuel cap removed. A second person should hear the bubbling at the open filler cap.  If the line is free, then your attention should turn to the carby and the fuel cut-off switch solenoid, which I've had fail many years ago, in outback NSW.  If still no joy, then time to remove air cleaner & the top of the carby, & remove jets etc. & look for blockages. 

If all that fails, then check the contact breaker (points) gap in the distributor. If the rubbing block on the points wear badly, You can get to a point when the engine is running the points open enough to run the engine; but at idle they barely open.  Let us know how You go.

Cheers Banjo

[79rolla]

Cheers Banjo and altezzaclub. 

It does have a old fuel pump. So we are going to have a look at it. We know points aren't sparking 100% of the time. They are sparking 90% of the time. So it could be spark or the fuel pump.  It has done it with multiple carby's so we will have a look today to see. It does also run very rich. So we will be having a look today and ill let you all know how we go.

 

Cheers 79rolla 

 

[Banjo]

From your latest advice, I'd say it is definitely ignition related, although it would not hurt to carry out the fuel pump tests, suggested, anyway. As it is intermittent, I'm going to have a guess that it maybe ballast resistor related. There are a lots of things in the ignition system that can go wrong. Only way is check it from ignition switch to spark plugs & everything inbetween. We've come across some "doosies", over the years.

Cheers Banjo

[altezzaclub]

"We know points aren't sparking 100% of the time. They are sparking 90% of the time."

If you haven't replaced the condensor it is time to do it, they make the spark good or bad.

Rich is interesting, do you think it might be running a high fuel level, either float level or dirt on the needle seat. Is one of the other carbs any better?