97 7.3 diesel just picked up for my son, were told it was a bad pcm , that was the conclusion because there was no wait to start light coming on. They replaced the injector wiring harness because apparently it was frayed.
That was it, we picked it up assuming it needed the pcm.
After further inspection once we got it it looks like someone has a push button installed for the glow plugs in lieu of the wait to start light. My assumption is it broke a while back and that was the fix for them? Idk...that was the first discovery, next we put the pcm back in that they had pulled, and the fuel Gauge was completely empty so our next step...put fuel in it lol!
Got some fuel in it, now he can get it to crank but will not start . Some light smoke coming out of exhaust. It will start on starting fluid (he said he knows not a good idea!)
The fuel bowl was dry, so his step right now it's to put a line and try to direct feed it fuel and see if maybe it's a fuel pump or line? Does anyone know it is a mechanical pump or not? I think we are not getting fuel.....Where do we check next..
Question is, where do we start before jumping to pcm, or idm issues?

 

It has a mechanical pump in the valley of the engine. If no wait start light check fuse 22 under the hood. It is for the fuel heater. If blown disconnect the wire from the fuel bowl and put a new fuse in and try it. Does it run after you get it to start or does it shut off again? Make sure it is full of oil.

 

Check the fuel filter bowl and see if you have fuel there. Check the fuel pressure and see what you have while cranking.

 

Crank/no start flow chart this may help

 

It does stay running but just for a sec. We have checked the fuse, it is good.

 

fuel bowl was dry, I will have him check the fuel pressure

 

I've never actually read a story of somebody using starter fluid and having the worst case scenario happen. But, it sure would suck to be the person who has that story. The science behind why you shouldn't do that is more than enough reason for my to never even consider it

Is there a chip on the PCM? There's a spot directly on the back of the PCM where a chip goes. If there is one, remove it then try.

What is the history of that PCM? Did somebody try an amateur fix on it? Did it get wet? Has it been rebuilt?

Did you check all your battery connections? If that short wire that runs from the positive terimnal on the passenger side battery to the jumper relay on the fender is messed up you will have power to your can, gauges, radio basically everything. When you go to turn it over, it can immediately lose all power or just crank. Unlikely but it can happen. That's what my most recent issue was.

Do you know where they got the injector wiring harness from, or if it was hooked up right? Crappy quality ones could fail immediately or shortly after you install them.

Try replacing the CPS (camshaft position sensor) with a motorcraft only.

These are just some things as a general background. If your fuel bowl is draining then check fuel pressure when cranking and again if you get it running. Check all the lines and ensure they are tight (there are like 5 or 6 in the valley/fuel bowl area). Check the rubber hoses. Check the actual fuel bowl itself. Make sure you don't have a leak in it.

 

If your getting light smoke then your IDM is probably OK unless you sprayed starting fluid real heavy in there. You don't want to make windows in your block or bend rods. Also unplug all four valve cover plugs to see if you have burnt pins.

 

How much fuel did you put in it? Over 1/4 tank? Looks like more than one problem. Need to sort out one at a time.

 

 

starter fluid reacts with the glow plugs to cause the catastrophic failure.

So, if you have push button glow plugs setup, you're more safe to use starter fluid.


If it was empty on fuel, it's probably been sitting a while too. The FPR is probably dirty as well as the fuel filter and it's got air in the fuel rails.

Clean the FPR assembly and change the fuel filter.

Then crank and give the starter time to cool without cranking too long till it fires.

If it fires and stalls, let it sit and the air will bleed out of the system. Give it 5 minutes and try again.

Eventually it will fire and run rough and just let it idle and it will smooth out when the fuel rails get better.

As well, make sure oil is topped off, as they are HEUI injectors and it could also be causing you goofie issues.

If it still wont start after a while, check the valley below the fuel bowl for oil, that will let you know there is a High Pressure Oil leak and you probably have a bad o-ring on one of the oil rail lines.

 

So, there was no chip. Don't know if there ever was at any point but is not currently.
He bought two new batteries all is well with the connections etc.. Good there .

We had a friend come over with a scanner and was able to read for only a sec, no codes at that point but then wouldn't read anymore.
He suggested the condition of the engine wiring harness was rough to replace that . So we did replace the engine wiring harness and still nothing .

We had the diesel tech from the shop I used to work (different guy from the first time) at come over with an old pcm from a 2000 automatic truck hook up and check and see if it worked. Scan tool read that pcm and only had trans codes as my sons truck is standard. Got it to fire once but then the batteries sounded real weak and wouldn't go again.
The tech said it was The pcm that was bad since it fired with the alternate one.
After pulling the old pcm from his truck to get the code and see what we could find as a replacement it looked like it had been wet at some point.
So....now we are at do we send it out for repair and find out it can't be repaired due to water damage and be out that money, or he has a buddy who has the pcm from a 97 250 automatic he can get??

now I know it will throw codes for the trans but isn't there a way to program it to manual I thought I had read??

 

If he can get the 97 pcm from the auto, it will or should run the truck. I ran a auto pcm (my spare tee5} in my truck while I sent my standard pcm to DP tuning to be re flashed for the 60 hp tune . The auto pcm ran great just the idle was a bit higher which was no problem. This was my findings, some may say different. I think DP tuning can reflash to what ever you want but not sure. You could give them a call.

 

The truck WILL run with the Auto PCM, but it will have idle issues. It will essentially try and "hunt" for RMP and jump around as its looking for the neutral sensor on the auto trans which isn't there.

Sadly, your issues overall were probably not wiring harness related and you wasted some money on that.

As well, get that starter off and clean those connections and have it tested. If you replaced the batteries, you can get a good **** ton of cranking before they die unless you just got the cheapest ones out there. You want 650 CCA's at the minimum.

 

Actually, I think the requirement from "back in the day" was 750CCA each. Nowadays most 7-year group 65 batteries are at least 850 or 875.