Hello everyone. Been lurking around here for some time, finally decided to get the experts involved. Have a 97 350 PSD I bought a few years ago. Since day one it barely started when cold, white smoke filled the neighborhood when it did. About a year ago I was driving and I had a significant loss of power. Pedal to the floor and could barely keep it going, I tried to make it the last couple miles home but failed and had it towed. After recharging the batteries I could get it to start here and there, but it would not stay running. Gradually it got worse until it stopped starting altogether. It would crank and still tons of thick, white smoke but no start. Kept trying here and there but didn't have much time for repairs as this is mostly a utility truck and was not a huge priority. I started working on it again a couple months ago, but have not made any progress. If anything, it seems worse now than before.

What I've done recently:
Valve cover gaskets and harnesses - Passenger rear connector was completely melted
All 8 Glow plugs - Motorcraft
CPS - (Ford) RPMs have been moving during crank until a couple days ago
Both batteries are new
Fuel filter
New oil and filter
Unplugged ICP, no change


What I know:
No service light, but I've killed the batteries many times cranking it
WTS works fine
RPM's no longer showing up, have ordered a new CPS
GP Relay checks works fine according to multimeter
White smoke no longer comes out during cranking
Fuel Bowl fills
HPOP is full

I'm really at a loss now and not sure where to go next. From what I have gathered from reading many posts here, I suspect that the IPR, IDM, PCM, etc may be the next course but I really cant afford to just throw expensive parts at it. I have a buddy with a 95 7.3, he will let me swap IDM If that's a likely culprit but not sure about compatibility and don't want to ruin his. So here I am, looking for advice and trtying to soak up the knowledge. Thanks in advance for any help.

 

Put your IDM in his truck, if the no start follows to his truck, you have found your problem. If the IDM is bad, one from any truck with a 7.3 stroke will work. Measure the fuel pressure at the Schrader valve on the fuel bowl. It should read at least 20 lbs while cranking. The fuel pump is a 2 stage pump, so even if the low pressure side is filling the bowl, the high pressure side may have failed.

 

After IDM check

https://drive.google.com/file/d/0Byb...1qRU1VVGc/view
Print above out and it should get you to where your problem is.



When starting, what temp is it?
Does volts drop when turned on? GPs will pull battery down to 11 or so volts

 

I won't be able to try the IDM swap until next week, but I will check the pressure when I get home from work. I hadn't really considered fuel pump yet, is there just one or is there one in each tank? I have tried both tanks for what it's worth.

 

Wow, that's an awesome flow chart. Thank you!

As far as temp goes, I've tried anywhere from the 30's to the 80's over the past 6 months or so and no difference. I also have plugged it in several times but nothing. The voltage gauge definitely drops when turned on, but I haven't checked actual voltages. I just know that it does not seem to crank as long as it should with 2 new batteries before they die. I did test the GP relay and it seemed to be working normal.

 

What batteries did you buy?
Did you clean all battery connections?
Follow this if not
https://www.ford-trucks.com/forums/1...ou-cranky.html

When you charge the batteries, what charger do you use?
When I use my 20 amp charger, it takes over 10 hours to charge if I depleted them.

 

I did not see a starter listed. My 300SD refused to start below 45F with an old starter and a fresh G49 battery... 7.3 acted same way. Refused to start with two fresh G65s under 50F.

White smoke output is a good sign to me. Could be low FP still or HPOP can make barely any pressure to atomize the fuel.

You have a 97 so the PCM is OBD2 compliant. Get a good tool on there and it will show the numbers, provided the ICP sensor is good. My 10 year old Edge Insight does with updates only.

 

Cheap scanner to monitor your engine with an android device


Torque Pro
https://play.google.com/store/apps/d...g.prowl.torque

Use the communication in the profile
SAE J1850-PWM

make sure you add in Ford PIDs

https://play.google.com/store/apps/d...ch.CarGaugePro

people like it cause it will pull codes, buzz test and CCT

 

One fuel pump and is located in the engine valley, just behind the fuel bowl and it's driven by the engine cam shaft. No pumps in the tanks. As mentioned above check the fuel pressure while cranking. Easy to do with a tire type air stick gauge. Just get a cheap one as the diesel fuel will destroy it eventually but it will get you a good reading for simple testing. Must crank or start the engine for a reading so a helper is a good option.

Cranking ~ 20 PSI or so.
Running ~ 50 - 60 PSI or so.

 

I bought a pair of Interstates from Costco a few months ago. With all the cranking I have charged them a dozen times already. When I do charge, I usually let it go over night. I didn't do anything to the connections, I'll take a look at those.

 

Yes, I did replace the starter shortly before my problems started. That wouldn't cause the engine losing power and dying, but I do need to replace again as I think I've completely killed it with all the long cranks I've been doing. Batteries are fully charged and went out to crank and it barely moved. After a couple tries it's now just clicking. I got a Forscan adapter today and hooked it up but since it wouldn't hardly crank I haven't gotten much info yet. Looks like another starter and re-evaluate.

 

Question for the experts... I tried cranking on it today and got very little movement on freshly charged batteries. Batteries were showing 12.5v each, and I tested the GPR and everything seemed to be correct with key on and off. However, I noticed that the relay was incredibly hot even long after it clicked off. I disconnected the power from the relay and noticed everything seemed to have more power (interior lights, HVAC, radio). I have also noticed when the relay clicks on the voltage gauge drops by what seems like 2 volts or so. So even though the voltages seemed ok at all the posts or the relay, could it still be bad and causing too much battery draw? And could this have contributed to the starter failing?

 

What GPR do you have, original OEM or aftermarket bigger ones. If the GPR coil is case grounded then there will be power always to the GP's with key ON causing this issue. But you indicated you could hear the GPR relay click OFF? When it clicked OFF is there still battery voltage on each big lug? Any way to post a picture on the GPR connections as that would help.

 

Was hoping you could help, here recently, last two weeks or so, went to start truck, key on, had power for about 5 seconds, everything went dead. No power to interior, or anything. left key in ignition, started looking at relay's/fuses in engine compartment, checking battery terminals, etc. Then after a couple of minutes, the key in ignition chime goes on, truck starts and off I go.

Batteries both new and good, alternator newer, charges fine.

Happened again on Friday, same scenario, came back to life on its own drove fine all day long.

Thoughts?

PS Nice Flow Chart

 

That's a tough one. Not long enough to give you time to test things.

Bad cab grounds possible. They are located near kick panels.