7.3 shuts off

[whitecc250]

Recently, my 2000 7.3 Powerstroke has been doing some strange and odd things. Several times over the last month, the big mule just decided it wants to shut off. Most of those times it had cranked right back up, but on recent shutoff's, I have had more difficulty than normal to get it to fire back up. I have noticed that when it is hard to get started, that the "wait to start" light will go off almost instantly when key is turned on. Sometimes, the light will actually cycle on and off very rapidly, Sort of like there is a relay losing and regaining connection. I can actually hear a relay or actuator clicking under the left side of steer column ( where the fuse panel is). I have pulled and checked the relays and fuses in that area and did not notice any bad connections or burnt smells. No blown fuses, loose wiring (that I can tell), that are associated with any of the Injector modules, PCM, etc.

Are there other components behind the fuse panel related to the glow plug circuit, Injector modules, etc. that I can not see without removing the fuse box?

For reference, I can hear the fuel pump running (before it times out for no start?) and I have changed out the CPS several years ago with a unit from IH. Also, nothing in the Main Fuse Box under hood seems to be amiss. I will admit that I have not checked all connections under the hood and will be looking at them in the morning when the sun comes up.

Another note, today after running to town for some quickrete, I had left the truck idling for the wife to stay warm while I was out and when I started to move, the big mule acted as if you stuck a hot prod to its rear end and took off like it had a super super programmer in it. Man, it had the power! But, no trans shift after 1-2. Thought it was demonized for a moment. Pulled into the parking area, shut down ignition, restarted and all seemed normal. No codes set @ dash. Made it home with no other problems, but later after coming out of the field heading to the house, it started its shutdown routine again. I finally coaxed it into cranking, and made it back to the house.

I know that this is kinda long winded, but you guys have any thoughts, PCM, Injectors, CPS (again)? I normally do all my own wrenching and have owned this truck for 8 yrs, but I seem to be at a loss when it comes to non-mechanical (electrical) issues that I can not see what is broken.

Thanks for any info.

 

[iracemine]

its gonna get asked so Ill do it first. pull your battery terminals and get rid of the dead lead? if not, Id try it.

 

[JRJ04]

sure sounds like a CPS to me...

 

[JLDickmon]

sure sounds like a CPS to me...

yeah, me too..
possibly the #30 fuse in the underdash fuse block having loose terminals.. would explain the strobing WTS light

 

[whitecc250]

Thanks for the input, guys. I did call myself checking the #30 Fuse and did notice that when running, the 7.3 will die when this fuse is pulled. Maybe I need to look deeper into the wiring/connectors. I will take another look this morning. I had also thought that maybe the CPS may be faulty again, but was hoping not. The way that it was acting, (with the WTS light rapidly strobing for 1-2 secs at same time that key is turned on) made me think that there was a connection or relay problem). On this year model (2000), cant the CPS be checked by observing the tach needle while spinning over when in the non functioning mode?

Also, the truck has a piggyback SuperChip programmer installed. I guess that I should have removed it at first sign of trouble. I will remove it and drive it for a while to see if that may be some of the issue.

Thanks again, I will post any progress on what I find.

 

[BIG JOE]

its gonna get asked so Ill do it first. pull your battery terminals and get rid of the dead lead? if not, Id try it.

I'd Second That.

sure sounds like a CPS to me...

And maybe That too ?

 

[rammertide07]

On this year model (2000), cant the CPS be checked by observing the tach needle while spinning over when in the non functioning mode?
QUOTE]

Non-functioning mode??? On normal start-up, yes you should be able to see the tach jump during the start. But pulling the pcm fuse (to cause a no start) will not diagnose the cps as that is were the cps signal goes too.

I think the cps would be worth a shot, cheap and quick enough to do. If not then you got an extra in the glove box. But I think your problem lies in the electrical connection somewhere....and I hate tracking them gremlins down. Good luck

 

[JLDickmon]

Thanks for the input, guys. I did call myself checking the #30 Fuse and did notice that when running, the 7.3 will die when this fuse is pulled.

that one contols the fuel bowl heater (often cause of failure see here ) and the IDM/FICM

was hoping the fuse was just loose in the spades..

 

[Tail_Gunner]

that one contols the fuel bowl heater (often cause of failure see here ) and the IDM/FICM

was hoping the fuse was just loose in the spades..

Bad i.e. intermittant fuse maybe. I've seen fuses that were cracked, making intermittant contact.

 

[whitecc250]

After looking it over some more today, I think that I may have stumbled upon the item causing me the problem. While trying to determine if there was a loose connection, wire, terminal, etc. around and behind the inside fuse box, with the engine running, I inadvertantly hit the rear of the PCM box where the programmer is piggybacked and the engine shutdown instantly. Acted just as it had done before when it died going down the road. Maybe coincidental, I dont know, but the programmer chip was loose in the socket upon investigation. Looking at the terminals and contacts of the chip, I did not notice any that had corrosion or arcing, so I thought that maybe it had wiggled loose from several years of being plugged in to the rear of PCM. As of now, my intent is to leave it out for several days and see if the problem returns. It had gotten to the point where I was looking for it to shut down every time that I drove it. I will see if this is the issue or not. May be time to invest in a different type of programmer.

JLDickmon & Tailgunner, I was hoping to find one of the fuses or connections loose which would have been an easy fix, also. The strobing cycle of the WTS light and cycling of the relays could have been related to the programmer losing connection instead of a wiring circuit/fuse, huh?

I did drive the big mule today to the parts house and back with no problems. We'll see.

Thanks again for all the ideas, I will keep this post up if the problem reoccurs.