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?

[Geezer914]

1+ on the AFM not being connected. Check for vacuum leaked. The intake boot may have a crack.

[tshih914]

1+ on the AFM not being connected. Check for vacuum leaked. The intake boot may have a crack.

I assure all that the AFM is plugged in and my fuel pressure gauge reads 28psi. One other piece of info is when the engine is "idling" at 3000 rpm I placed my hand to cover the nozzle of the air box housing feeling for vacuum from the air passing through the air filter into the AFM and felt little air flow! This means that there is an air leak (like when you adjust the idle by opening the screw at the base of the throttle to bypass the AFM). I had replaced the intake boot when the initial problems showed up. When searching for vacuum leaks there are lots of hoses and connections and even the O-ring gasket under the oil filler cap to check. Also is there an auxiliary air flow sensor in the 1974 1.8L FI system?

[wonkipop]

1+ on the AFM not being connected. Check for vacuum leaked. The intake boot may have a crack.

I assure all that the AFM is plugged in and my fuel pressure gauge reads 28psi. One other piece of info is when the engine is "idling" at 3000 rpm I placed my hand to cover the nozzle of the air box housing feeling for vacuum from the air passing through the air filter into the AFM and felt little air flow! This means that there is an air leak (like when you adjust the idle by opening the screw at the base of the throttle to bypass the AFM). I had replaced the intake boot when the initial problems showed up. When searching for vacuum leaks there are lots of hoses and connections and even the O-ring gasket under the oil filler cap to check. Also is there an auxiliary air flow sensor in the 1974 1.8L FI system?

BTW @tshih914 - thats not the fuel pressure test for L jets.
you are going to find the correct test in the links to the manuals i posted previous.
you are actually looking for 35ilbs pressure when you operate the AFM flap.
its all in the manual. you can also test flow which is important as well as pressure.
again all the manual. but that is jumping ahead at this stage.
you need those manuals. the fuel pressure regulator is non adjustable in the L jets.