95 F250 crank, no start. 5.8 L

95 F250 5.8 L Crank, no start. Throttle not responsive. Check engine light.


I have been trying to use the Fasttec method to find the problem.

Truck had been starting until i unplugged one sprk plug without grounding it ......to investigate something. Made me suspect i fried something.

Fuel:
I have fuel pressure at rail with either fuel tank. I can hear pumps prime.
I can hear the two fuel injectors that I listened to click.
Wont start even with help from carb cleaner into intake.

Air:
Filter was not dirty. No obstructions.
Throttle body not dirty.
Maf sensor not ruled out.

Spark:
I replaced plugs and wires. They were old. I can see spark from grounded plug.
I installed new ignition coil. It lights up plug tester.
Installed new entire distributor. Have tried 11 to 15 degrees of advance. Nothing.

I have tried starting with and without the computer bypass.

Other:
I checked all fuses with test light.
All relays in under hood box work.
Coolant temp sensor is responsive.
Tps is not very old.


Wtf? I have ordered an obdi to obdii adapter. I will see what codes say.

I wonder about ignition control module? Maf sensor?

Does your truck have california emissions? (I only ask this as fuel injectors and a few other items have seperate circuits for individual components like each injector has its own ground side switched pinout on ecm)

Which end of plug wire did you disconnect from (at the cap or at the plug)? Is you icm mounted with distributor or is it mounted to the drivers side fender?
Have you checked if you have a 5 volt ref? This engine should have a map sensor only either mounted on firewall on passenger side or near the ignition coil. Which you can test with a dvom that can read hertz and a cheap fluid transfer pump that looks like a bike pump to check if map is working like it should. I would ohm test the coil and test the icm. Where was the exposed end of plug wire touching at or near? Here is a worksheet to reference. work down the list and don't skip anything. Let me know what you find.

Update:

I cannot detect an injector pulse on the two injectors that I tested. Kinda strange because I Thought I could hear a click when I put screwdriver against them. Resistance across four Accessible injectors Was about 16.3 ohm.

I had a new PCM installed not long ago. I dont see any visible wire damage. I saw a post that a bad TPS will cause the puter to shut off the injectors....anyone else believe this? I will try to start with tps unplugged.

The obdi to obdii adapter i purchased only produces “bad link” so i guess my cheap code reader doesnt work with it. Or could that mean a bad pcm? I will check for 5v reference to thermistor.

I really appreciate input. I am near the end of my skill set....

Thank you!!

Truck has been in California so i think it’s California emissions.

Icm is on driver siide wheel well.

It has maf instead of map sensor.

Truck only has 55 k miles.

California emmisions ok... all injectors have there own wire going back to pcm. Let me see what I can find out

[quote="Corliss" post=40294 I saw a post that a bad TPS will cause the puter to shut off the injectors....anyone else believe this? [/quote]


This is TRUE!

With an open TPS showing 5 V on the signal wire the computer takes it as "clear flood mode" and will not pulse the injectors. Spraying propane or something similar into the intake while cranking will make the car start and running....til you shut it off and you 'll have to repeat the procedure.

Here is the images from my book and where they go to the ecm.

For the tps sensor

Brown/ white wire 5 volt ref from pin 26 @ ecm (this should have 5 volts all the time with key on)

Grey/white tps signal to pin 47 @ ecm (this voltage with key on throttle closed should be .9-1.1 volts)

Grey/red sensor ground pin 46 @ ecm ( .3 volts or less cranking)

Please note the colors listed is the wiring harness colors not the tps sensor wires coming from connector to tps.

Also included the maf sensor image as well

Red wire 12 volt power feed (fed power via ecm /pcm power relay spliced into pins 57 & 37 of pcm/ecm pin 2 @maf is 12 volt power

Tan/light blue pin 9 @ ecm pin 4 signal return

Light blue/red pin 50 @ ecm pin 5 @ maf signal

Black/ white pin 3 @ maf ground wire grounded near sensor

The two outer pinholes on your connector should be empty

Hardtopdr2 wrote: Also included the mad sensor imag e as well

Finally you got the villain nailed, even with a foto. I was after him for years, but that bloody mad sensor always fooled me.....:lol:

Sorry, couldn't resist.

Lol got to love autocorrect