1991 320i wont idle unless you put fuel direct into manifold

Look for a vacuum leak around the inlet manifold , also check rubber vacuum lines for leaks.

Try TPS. Throttle positioning Sensor. This sets base idle. (Unless this model is too old for that sensor)

To start with, you have a throttle body instead of a carburetor.
On that throttle body is a component called an air control valve.
That valve is how the computer controls the idle speed. It should open and close the air flow into the intake manifold as needed.
Is the check engine light on when you are driving ? Have you checked the fuel pressure ?

First thing I would do is a compression test on cylinders, then fuel pressure test. Make sure your starter relay is good. If it is cranking over but not firing could be fuel relay, fuel pump, and could be as simple as a vapor lock. Spray some starter fluid in the intake, if it fires up for a couple seconds, then tells you not getting fuel, and this narrows down the search to the fuel pump relay, fuel pump.

Now your statement is YOUR CAR wont start or idle, as you can tell that is two different things. Which one is it, wont start at all? or starts then dies because it wont idle?If it wont start, then check the things I just advised, if it wont idle, then that could be plugs,coils,idle arm, fuel filter possibly clogged. List goes on and on. Need to know little more detail of what exactly it is doing, and what you have already checked or tried for me to dissect it down more direct with trouble shooting. I can help you for sure, just little more info needed, or you can go through the list I just said and it will I am sure fix problem once you check and repair or replace as you come across that problem area that is not functioning proper. Thanks Mike

Clogged fuel filter.
Turn the truck all the way off.
Disconnect the two lines at the top and bottom of the fuel filter -fuel will start to run out of the upper line.
put in a new fuel filter being careful to get the flow direction correct.
crank the engine awhile until it starts.
If the problem persists it could possibly be clogged fuel injectors or a faulty idle speed sensor.

apply a light force to the gas pedal and start the car continuing to regulate the rpms with gas pedal if you can make the car idle with the gas pedal then you will probably need a new idle air control valve

check for air leaks on intake manifold,and check your fuel pump

Low / uneven idle problem can cause by a lot of components.

Dirty air filter

Dirty injectors + o-rings

Vacuum leak at intake manifold and vacuum hose.

Bad Idle Air Control Motor (IAC)

Low compression (170 psi + is OK)

Start cleaning and repair these trouble spots and see is there any improvement.

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For more advance DIY'er then you may try this.

Use a can of Berryman carburetor clean to locate the vacuum leak.


SEE SAMPLE PICTURE HERE


This is a 20-30 minutes job.

Vacuum leaks can occur in following locations.


Intake manifold AND/OR vacuum lines.


Intake manifold is not accessible unless the engine head if off.

You can still check the potential leak by spraying some Berryman near the intake manifold.

Listen for rpm increase after you introduce the Berryman (FUEL) at idle.


Do the same starting from the brake booster unit (the round unit) on the drive side fire all.

Carefully listen for increase of RPM right after to spray the Berryman to the potential vacuum spot.

Get a friend to HEAR the ROM increase or monitor for RPM on the tech.

DO NOT AIM the Berryman into any heat source.


PLEASE RATE my answer if it is useful to you.

Early Toyota fuel injection use a cold start injector, it only works when the engine is cold. It is located in the intake manifold. for the mean time you can turn up your idle by turning a flat head screw in your intake manifold counter clock wise . It could be a coolant temp switch for the injector that has gone bad also.

sounds like dirty fuel check your fuel filters see if ther blocked