Had customers car dropped off few days ago -- dont know much about these and dont have a lot of information about them.

Here is scenario --
Starts up great idles for days on end -- as soon as throttle plate is moved even slightly engine shuts off -- have to crank it til it fires back up like it is flooded but of course cant use throttle or it wont start at all.

fuel pressure is running 35 psi into fuel dampeners. --

smells rich --

tried blocking off auxiliary air valve -- valve is still open slightly at idle with it warm.

pulled throttle body off and cleaned contacts for throttle position sensor -- I have the proper resistance at idle and then moves open and closed up til it reaches full throttle.

it seems like as soon as it clicks for coming off of throttle that it shuts down engine like you just shut off the key. Then it is hard to start(cranks long time) til it fires back up and clears itself out.

any thoughts would be helpful. thanks.

With the throttle plate moved so that the idle contacts are open, are there sparks available at the coil/plugs when cranking, or are sparks available only with the idle contacts closed?
How about when WOT contacts are closed?

If there are sparks in all conditions, connect a voltmeter (an O-scope would be even better) to an injector positive (+) lead (the brown wires are grounds). By selecting a voltage scale below 12V a pulse should be observed when idling. Does that pulse cease when the idle contacts are opened?

spark at all times. tested with bosch probe and show voltage through spark plug wires at all positions of throttle position when cranking --

each time throttle plates open it kills engine and I am assuming that injectors keep firing because the engine gets flooded --

As soon as the engine stops, injector pulses are cut off. A rich condition can be caused by the cold start valve sticking open, however, a rich condition will usually not cause an immediate engine stop with throttle opening, rather, there will some stumbling until the excess fuel is burned off. What is being described corresponds to a lean condition.

With the high fuel pressure (28-29psi is normal) mixture adjustments may have been set very lean (short pulse time).

What do the plugs tell you? Fuel soot (dry black), clean, or oily (wet, shiny black)?

When it cuts off just as soon as you open throttle it will restart but it has to crank for probably 15 to 20 seconds before it will fire -- spark plugs are black but when I pulled out were fuel fouled so will check for condition after it runs for bit.

checked fuel pressure at fuel rail after regulators and running 30 psi --
ohmed out injectors 2.9 ohms each cold

it smells like it is running rich when its idling

Checked for injector pulse -- it is consistent flashing --

as soon as throttle plate opens -- kills engine immediatly -- shut key off and it takes extended crank for it to fire and then clears out and runs smooth up til you move throttle plate. fuel pressure did not drop when it died off -- stayed consistent at 30 psi

just pulled plug after running for while black and sooty but dry.

When the idle contacts are closed, i.e., throttle plate closed, the injector pulse time is set by a potentiometer adjustment on the ECU, and is independent of manifold pressure. As soon as the idle contacts open, manifold pressure becomes the main signal to set pulse time. If the manifold pressure sensor has an open or shorted winding in either the primary or secondary circuit, it can cause a shutoff of injector pulses.

To check the pressure sensor, pull off the four-pin flat plug, and use an ohmmeter to test the windings. The center two pins are the primary, nominal value =88ohm. The outer pins are the secondary, nominal =350ohm. Neither winding should be shorted to ground, or to each other.

Additionally, check that the ignition points are in good condition and properly gapped, and that movement of the breaker plate does not interrupt the primary circuit.
While inspecting the distributor, clean the injection trigger contact sets (4) that are in the base of the distributor, under the ignition breaker plate.

Check the manifold pressure sensor and see if it holds vacuum. If it doesn't, it will signal to the ECU to run rich. This condition causes sooting of the plug and black smoke from the exhaust.

checked map sensor -- map sensor holds vacuum -- no leaks from manifold to map sensor
readings are same as frank suggested but opposite pins -- middle is 351 ohms and outer pins are 93.2 ohms -- no shorting to case or each other --

Also -- A question --

if you go to full throttle does it cut out injectors?

I know with other manufactures in flood condition it will shut off injectors if you go to full throttle.

thanks for all the input

checked the resistance of map sensor -- inside pins were at 351 ohms -- outside pins at 93.4 ohms -- no grounding to case or either winding -- this was backwards from what frank submitted. but I assume correct just different pins then described?


checked and made sure map sensor held vacuum -- no leaks from intake to map --

Probably there are not two sets of inside pins; try again.
The respective values are correct.

How many pins are on the throttle valve switch? Five? If so, three are for the closed/WOT contacts, and the other two are connected to a variable resistance track that is very much like that of a TPS. If that track is open, it may kill the injection signals.

there are 4 pins for the map sensor -- middle 2 pins had resistance of 351 ohms outside pins were 93.4 ohms

I cleaned throttle switch and checked the resistance per a previous article I found. I have the proper signals coming out of throttle position switch and can hear injectors firing off as switch is activated. actually seems to load it up with fuel once engine is killed and takes longer to crank before engine fires due to build of excess fuel in intake after engine is killed by moving the throttle plate.

I ordered an ecu today. I am not condifent that it will fix it but hopeful. I will update as soon as I get ecu --

if anyone has any more thoughts I have the car for a week and can keep testing components. Just trying to understand this car little more.

thank you for all your input so far.

Installed new(reman) ecu -- now vehicle runs and has acceleration but as it gets to higher revs just before it shifts gears it bogs down and tries to stall --

ordered a second ecu and installed that. vehicle runs like a top.

Thank you everyone for your input

Glad you sorted it out .