After browsing and trying many things on this site. I figured I would throw this out there.

Pulled in Driveway running, few hours later no start.

Problem: NO spark at Distributor and Fuel pump "clicks" but can't here it run.

have Replaced:
Coil ( have power but no pulse/dwell on back side even after new dist.)
ICM
Distibutor
Checked Coil Wire

Question 1: Can bad fuel pump cause no spark in the PCM engines?

Question 2: Is it easy to tell if PCM is bad?

Been a backyard mechanic for years... stumped at this point. 73 bronco is much easier to work on.

Can someone send me in the right direction?

Thanks in advance

 

1. No a fuel pump can not stop spark.
2. No it is not easy to tell if PCM is bad.

You can try unplugging the PCM and see if spark returns.
If it does then check to see if you have power to the PCM (pins #1, #37 & #57). Then check for a good ground to the battery (pins 40 & 60).
If the ground is good, power is good with the key on and you have spark with it unhooked and no spark with the PCM plugged in then you have a bad PCM.

 

Thanks Bill,

Will give that a shot in a few. Unplugging seems simple enough... any tricks or watch-outs I need to be aware of?

 

No just unplug it and check for spark while it cranks.
Some say you need to unhook the ground cable from the battery when you unplug and plug in the PCM but I have had no problem leaving it hooked up.

 

No spark PCM plugged in

Spark at Distributor PCM unplugged

Pins 1 (12v all time) ...... Pins 37 and 57 ( 12v when on)

40 and 60 continuity is good for ground...

Looking like a new PCM? If so any suggestions?

 

Yes it sounds like a bad PCM.
Maybe an auto parts store to get one.

 

Thanks for the information. Asking for any suggestions because I am having trouble finding one on-line hopefully my local guy can... if not maybe a pick-ur-part is in my near future... Thanks again and have a great weekend.

 

Yes the 1994 460 PCM is a little hard to find with the E4OD.
I have been looking for a spare for my F53 for a while. The closes one I can find is about $375.00 near Joplin, Mo. out of a salvaged F53. I do not want a rebuilt PCM from an auto part store.

I may be willing to buy your old PCM for the core price and I will pay shipping just to take it apart and find out what when wrong if you also have an E4OD transmission.

 

The 7.5 in 1994 will start with a bad PCM but won't stay running after (look at your electrical diagram...most times the electrical harness to the TFI is corroded due to being exposed to the weather non stop in front of the engine...I would definately replace the EEC and fuel pump relays before I did anything else and I would clean the hell out of the electrical connectors. Any water in those relays will producet very strange problems. Especially where this problem came on out of the blue (F'ng gremlins)!

 

Most of the time it will not start with a bad PCM.
Also on the F-series truck the TFI (ICM black in this case) is not on the front of the engine, it is tucked away way back on the inside of the drivers fender.
The relays are all so enclosed inside a box with a lid on it and it would be very hard to get water in one if the lid and the hood was open.

 

I believe the TFI Is on the distrivutor.

 

Not true in a 1994 460 Thread.

The TFI is a type of Ignition Control Module (ICM).
TFI: Thick Film Ignition. An ignition module comprised of a custom integrated circuit, Darlington output device and associated thick film integrated components.

Here is of a photo of the ICM of the type TFI for the 1994 F-series we are talking about in this Thread:

/

 

Don't be rude, the TFI was on the distributor but they were having heat failures so it was moved to the fender with a heat sink. On a 460 is could very well be still on the distributor.

 

The trucks with the 460 were the first ones to move it off the distributor in about 1989.

 

Your face.