Matt21

So put on those thinking caps and get ready for a challenge. I have a 96 Jeep Cherokee with the 5 speed. Darn thing ran beautifully until i washed then engine bay to remove all the oil. And now the darn thing wont run.
Things i have done.

Symptoms-
No spark no fuel
OBD scanner cant read computer
It will crank until the end of the world (or until i burn out my starter)

Things i have done in diagnostics-
Tried 3 brand new ECU's

I noticed that when I put the Black plug in just slighty and wiggle it that the fuel pump will kick in and everything seems to work fine. In doing this i was able to start it only for a few seconds before it stopped running. But when i fullly seat that black plug nothing works.

I replaced that black plug with a new one. Still the same thing as with the other ecu's.

The only gages that work when i turn the key on is the volt gauge and Oil gauge.


I know my check engine light mil and gen light are supposed to flash when you turn the key to the on position. But they don't. And i know that the ECU is good and is getting power.

Where do I look next. What part of the engine would cause this when hit by water etc.

Turbo X_J

What's a ecu?

Bangarang

Did you JUST wash it? If so that means you doused it with too much water. Wait a few hours for the water to evaporate and try to start it again.

XJPat

x2 if you just washed it give it a couple hours to dry with the hood open, especially if you power washed it.

Matt21

ECU i meant the computer. Also its been sitting for a week I even removed all the dist and spark plugs there all bone dry. But even then is wouldnt cause no fuel pump when i turn the key on.

investinwaffles

I washed my motor last Sunday after I went mudding, and my TPS died while I was on the highway on Tuesday.

I would check the CPS first because that can often times cause a no-start condition. Make sure the distributer is dry, and remove all electrical connections and let them dry out.

Do you have spark while cranking? Do you have proper fuel pressure?

93gc40

Yeah, you probably shorted out some sensor or the fuse box. Water and electricity don't mix.... Extreme care need to be taken when cleaning the motor with water. Also if you are plugging and unplugging the computer with the battery hooked up or have a shorted PDC.... You might be BLOWING the new computers, on installation.

EZEARL

Engine/engine bay hot from running when you washed it?

Matt21

Yea no spark when cranking. Fuel is good. Found a worn power wire running out of the Engine fuse box and fixed it but the problems still there. No dummy lights when key is turned on , no spark no fuel, BUt they are all connected in some way

Matt21

How can the PDC be shorted out? It doesn tlook like anything could short out since its just wires going to specific relays and fuses.

Matt21

Nope Cool as ice

EZEARL

Very good.

skife

time to play chase the wire, no spark? dloes the coil have power?

Matt21

I assume that the coil spark fuel ect is all controlled by the ECM thus why none are working. Like i said earlier when i turn the key i dont get any dummmy lights.

Things I have done so far.
Replaced the black plug that goes into the computer
ripped my dash out to ge better visibility to all the under dash wires.
Replaced The CRANK POSITIONING SENSOR
fixed a corroded wire leaving the engine control fuse box.
unwrapped the engine wiring harness to visually inspect all the wires. (didnt find anything)

Problems still there. Its has the symptoms of a BAD ECM i have another ecm coming in on tuesday. Because I am paranoid and always assume that any new computer that i get is defective or blown.





-Is it possible for the engine fuse box to be shorted out? how would i check if it is shorted out?
-How many fuses and or relays control the ECM and where are they located? That way i can check. Because From what i read theres only one fuse that controls the ecm.

skife

Don't assume.