91 351 W wont start or run

[furz4]

So it would seem just change the PIP sensor first since there is spark, the TFI is probably working. I think advance calls the PIP sensor Ignition pickup/stator. What level AC voltage would be expected at the PIP input to the computer? And have you ever heard of a TFI opening up and not passing the signal?

[furz4]

Is code 126 for the Map sensor on OBD1, perhaps my book is incorrect. If I unhooked the wiring wouldn't it go closed loop anyway and run like crap?

[trvcampbe]

If you unhooked the wiring it should go into open loop(limp mode).

[trvcampbe]

If the ecm is getting the incorrect reading from the MAP sensor,it could extremely richen or lean it back.Also retard or advance the timing incorrectly..

[furz4]

Sorry I stand corrected that's what I meant. I could see where a bad sensor might cause the computer issues but would it actually keep injectors from firing? I will pull the plug on it tomorrow and see if it starts in limp mode.

[trvcampbe]

Yes 126 is the three digit obd1 ford code for the MAP sensor..Which manual are you using?

[furz4]

It's and IEC reader, just looked at the book again and it does say map sensor and below that for code 126 it also lists cylinder ID circuit failure. It was pretty hot when I was scanning it i can't beleve I missed that. Do you think a bad MAP would keep injectors from pulsing?

[trvcampbe]

You said the noid light is lighting up ? Do you smell gas? If yes.Essentially the injectors are being pulsed but at a WOT rate..Check the vacuum to the sensor.....Check this site out..It is better than a haynes or chilton manual..I have a small repair shop and i use the Alldata on disc but you can purchase a single subscription for you truck...
http://www.alldatadiy.com/

[furz4]

They light up my test light, not a NOD light and no I don't smell any gas. It will only run when primed into the throttle body. It is holding a solid 40 PSI on the fuel rail.

[trvcampbe]

Are you connecting the test light across both injector wires and not a engine ground and one wire?

[trvcampbe]

You said you can get it to stumble some with starter engaged and working the throttle?What if you hold throttle wide open and start?

[furz4]

was going from one wire to ground both sides gave same indication. Should this be wired in parallel with the injector?

[trvcampbe]

You have a MAP sensor code,go with it..Its the process of elimination..If i pull 02 sensor codes on a vehicle,i first check the 02 sensors..Doesnt mean its going to be the 02 sensors but its what i have to go on..Yes a MAP sensor can and will cause a no start-fuel related condition..

[furz4]

I'll try disconnecting the Map sensor and see if it will run in limp mode first thing after work tomorrow and post results. Thanks to all that have contributed to solving this. Should be useful for others down the road

[trvcampbe]

You have a Positive and a ground going to the injectors,the ground is switched through the ecm..You need to put a light across the two..