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?

[Van B]

Boy does that all sound familiar.

I’d still like to know what changed from when it ran normal.

[wonkipop]

Boy does that all sound familiar.

I’d still like to know what changed from when it ran normal.

it does sound a bit familiar, but not completely the same.

he said he left it to sit in storage for a few years.
something in there gave up the ghost during rip van winkle period.

they don't like sitting around.


EDIT - i seem to recall you ( @Van B ) got some weird thing where your 1.8 would run at 3000 rpm and not do anything else when you had something off. but its a couple of years ago and i can't find that thread anymore. maybe its my imagination and false memory? there was something i was asked to do by you and i think it was see if mine would start and run without the AFM plug in. mine would not. but yours would? and it was the way the fuel pump in yours had been wired in after moving to the front. mine is still stock and fuel pump is run off the AFM contacts after cranking phase. i could have this wrong. but yours would run and it ran at 3000 rpm? until you hit the throttle. my memory is not that good.

EDIT EDIT - can you see where i am going with this @Van B ?
we have to find your thread again and go through it.

[porschetub]

Boy does that all sound familiar.

I’d still like to know what changed from when it ran normal.

it does sound a bit familiar, but not completely the same.

he said he left it to sit in storage for a few years.
something in there gave up the ghost during rip van winkle period.

they don't like sitting around.

(IMG:style_emoticons/default/agree.gif) reckon the only thing that will cause that is a sticking air gate in the AFM,most normal air leaks will cause a high idle of say 1500 but generally not more but not 3000.
I had this with one of my old BMW's after top overhaul and found the AFM was full of crap,run great after a good clean,same system but the 914 AFM is known to suffer issues after backfire of I'am thinking that's happened.
Cheers.

[wonkipop]

Boy does that all sound familiar.

I’d still like to know what changed from when it ran normal.

it does sound a bit familiar, but not completely the same.

he said he left it to sit in storage for a few years.
something in there gave up the ghost during rip van winkle period.

they don't like sitting around.

(IMG:style_emoticons/default/agree.gif) reckon the only thing that will cause that is a sticking air gate in the AFM,most normal air leaks will cause a high idle of say 1500 but generally not more but not 3000.
I had this with one of my old BMW's after top overhaul and found the AFM was full of crap,run great after a good clean,same system but the 914 AFM is known to suffer issues after backfire of I'am thinking that's happened.
Cheers.

yeah though this is even weirder and its something @Van B discovered.

it could be internal to the AFM like dirt, corrosion.wear on contacts etc.
but @tshih914 does have a new/rebuilt AFM now. i would think its probably pretty ok in those terms.

@Van B is on to this one i think.

if there was ever an argument for preserving a car in original condition - and by this i mean technically, not just aesthetically, it was during his relentless program to get his 1.8 running right. he knew i had a pretty unmolested car. so he kept giving me scenarios to try on mine. we didn't get the same outcomes. eventually between us all we cracked the fuel pump wiring trickery.

it sure is weird. but if that fuel pump is wired to the ignition circuit and it stays on, the car will run with the AFM disconnected from the ECU. but only with the TPS closed in idle position. no other position. and however it does it, it runs it at elevated revs.

and if its factory original wiring to fuel pump it won't run. it will fire, but it won't continue to run.