1974 1.8L engine fast idle then stalls, Fuel injection issues Options

[tshih914]

My 1.8L 914-4 with stock Bosch L?-Jetronic FI after being stored several years started to develop a hard to start problem. When finally started would stall when I give the gas pedal any input to raise the revs. I suspect there was some kind of intake air leak and while fiddling around had a backfire which blew the AF meter which I had Pelicanparts repaired. After replacing the fuel lines with the stainless ones from Tangerine Racing and flushing out the fuel system with Techron the engine started to run normally for a short time. Now the engine can be started and fast idles at 3000 rpm but again any input to rev up the engine results in stalling. The idle adjustment screw at the base of the throttle housing is fully closed. Any suggestions on how to fix?

[wonkipop]

ok
@Van B and @tshih914

i found Van's topic regarding the way the car will run with the AFM plug out.

link to the page.
goes over next 3 pages.

http://www.914world.com/bbs2/index.php?sho...6678&st=320


mine with OE wiring of fuel pump (runs when cranking and then runs off AFM flap which moves enough at idle to open the fuel pump contacts) would crank and fire and run for about 10 seconds from a cold start. conclusion was it was running off cold start injector.
after that on repeated starts it would crank, fire for a second and die.


starbear's with non OE wiring of fuel pump (pump on whenever ignition on).
good condition AAV. good condition decel.
would crank, fire and run but die after a longer period of time than mine.
repeated starts led to repeat of cycle except it ran at idle on its own for longer each time with revs gradually rising.
eventually getting out to running for 40 seconds.


van's with non OE wiring of fuel pump similar to starbear.
started with high idle (1400). slowly rose to 2000 rpm this was when the car was still suffering from a poor low idle at cold due to the non functioning AAV. but after a non functioning decel valve had been corrected. ran happily at high idle. van blipped throttle and it died. started it a second time and it repeated the effort.
van noticed the next day his AFM plug was out. plugged it back in and car started normally with its usual poor/low idle from cold.

as a result of this accident, wonki and starbear were asked to see if they could repeat what van's car did. see results above.

from this we worked out that if the ignition circuit was running the fuel pump an L jet would start and run in a strange way without the AFM plug. but only if the ignition circuit was running the fuel pump. wonki car with OEM wiring needed the hand off between the cranking circuit running the f p to the AFM flap which kicked forward and opened the contacts to run the fuel pump. no hand off with the plug out. so it dies instantly.

none of them would run once you kicked the throttle open as all of them were looking for the AFM signal once the throttle comes off the throttle position switch at idle.

this is the condition we want to try and tick off the list for @tshih914 .
to do this we have to work out what is running the fuel pump at start up.
is it ignition circuit modification or is it still stock.