Another No-Start 7.3L
So my truck has been sitting for about a month now in the driveway, waiting for me to get the time to address some issues. On Sunday, after what seemed to be forever, I finally finished replacing power steering pump, steering gear, both wheel bearing/hub assemblies, ball joints, tie rods, and all associated seals/o-rings, I was finally ready to drive my short bus! Well during this month of waiting for time to work on the bus, I found a guy locally that recently totaled his 2000 Ex and was selling his old Hydra tuner. I’ve been wanting to switch from my TS6 so I bought it. Downloaded the software, pulled my PCM, obtained the BOX code, converted it to the correct HEX code, swapped the tuners and proceeded to start the truck. This whole time the truck was down and out, I had pulled both batteries and trickle charged them. The batteries remained out of the truck until yesterday when I was done with the front end work. Fully charged when installed.
The truck started up great, no problems what so ever (just the typical initial exhaust smoke from sitting a while). Drove it all day, was BLOWN AWAY at the difference in power between the TS6 and the Hydra (way more power than my TS6 even in the 140HP tune), never had a problem until last night when I went to run to the store. Got in the truck, wouldn’t start……. WTS light came on normally, starter turned over strong as ever, ICP built up well over 500psi, but would not fire. Maybe about a month before I parked the truck for front-end work, I replaced the ICP (Motorcraft) because I found oil in the pigtail when I unplugged it. When the truck wouldn’t fire last night, I popped the hood, simply unplugged and plugged back in the ICP connector, and the truck started right up. I just assumed it wasn’t quite plugged in all the way and that was it. Well, this morning it did the same strong turn over but didn’t start. Unplugged the ICP and plugged it back in, still no start. Went back and unplugged it and left it unplugged to see if it would start, still no start…..
I was in a hurry this morning so I didn’t notice if the tach moved while attempting to start, nor did I look at the IPR, I will check these when I get home today. I also plan on checking the ICP pigtail/wires to make sure that’s not the problem. But before I go digging into this, can someone verify that this is not anything to do with the Hydra??? I know that there are a lot of different things that can cause a no start condition, and I have a list of things to check this afternoon when I get home, I just can’t help but think of something to do with the Hydra being installed. It very well could be totally unrelated, just can’t shake the thought. I’m going to check the oil level first thing, I know the oil only had about 1000 miles on it when parked, fuel filter was changed at that time as well. I have a mechanical fuel pressure gauge that I haven’t had a chance to install in the motor bay yet, gonna get that on asap so I can verify it’s not due to low fuel pressure. Any clarification on if the Hydra could be causing issues, or any advise would be greatly appreciated!! Thanks!
Before I had the batteries tested, I tried starting the truck and observed my monitor. Here are my numbers while attempting to start:
RPM: 150-200
ICP: > climbs to 2500 psi
IPR: 36-38%
IPW: 0.00
As stated, these numbers are while starting with one "bad" battery. Voltage would drop to around 10V but i've had my batteries run low in this truck before due to leaving a light on overnight and have had it start with lower voltage (it's cranked up before while JUST BARELY turning over). After swapping the battery, i was leaning heavily towards the fuel pump. But after this morning reading 55 psi, I'm not so sure. I have a Walbro GSL392 fuel pump at home that i'm going to install this afternoon if the weather holds up. We'll see if that makes a difference.
QUESTION:
Looking at my IPW, should my pulse width be something greater than 0 while starting? Or are those values not registering until the truck is actually running?
55 psi is more than enough to start the truck. That is not your problem.
55 psi is more than enough to start the truck. That is not your problem.
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I went ahead and pulled the IDM relay this morning and checked resistance when I got to work. I read 75 ohms across pin 85 <-> 86 and then O.L across pin 87 <-> 30. When I pulled the relay, I noticed it wasn't completely pushed in but I'm pretty sure it was in enough to make good contacts. No burn marks on the pins and the relay didn't smell burnt. When I get home I will run power across the relay to make sure it closes, but it seems like the relay checks out (I'm by no means an electrical expert so please correct me if I'm wrong)
I decided to see if there were other tests to run while I waited and found a resistance test for the IDM circuit so I grabbed my multimeter and unplugged the IDM. I found A LOT of what I'm assuming to be dielectric grease in the plug...so much so that I grabbed my shopvac to pull it out of the pin slots. Numbers below.
Pin 23 & 22 = 5.2 ohms
Pin 23 & 7 = 5.2 ohms
Pin 23 & 19 = 0.23M ohms
Pin 23 & 9 = 5.2 ohms
Pin 24 & 6 = 4.8 ohms
Pin 24 & 21 = 61K ohms
Pin 24 & 8 = 4.8 ohms
Pin 24 & 20 = 7.7 ohms
Pin 23 & 26 = "O.L"
Pin 24 & 26 = "O.L"
Pin 23 & 18 = "O.L"
Pin 24 & 18 = "O.L"
So it looks like none of my numbers are in the range specified (2.8 - 3.6 ohms). So with the 4.8 and 5.2 ohm average I guess we'll call it, seems like the UVCH on each side has a bad connections? Possibly the reason the plug to the IDM was loaded with grease? The high value on injector #7 i'm assuming could just be from a loose connection on the solenoid connector?
For injector #3 and #6, does a high resistance like that indicate a bad solenoid? And if so, injector replacement? I'm assuming if the solenoid is bad then I need to pull them either way.
I just got an email saying my Forscan account is activated so I'm going to try to do the buzz test this afternoon.
If still bad at uvch, then pull valve covers, inspect uvch and check the injectors themselves by unplugging the uvch. This could be as simple as 50 cent mod, or replacing uvchs.
I'd bet on just bad connections, but if you decide to replace solenoids, while you've got the solenoids off, check the clearance of the armature plates on the injectors to see how much clearance there is under the armature(should be around .004)
D+ == driver's side common. P+ == passenger side common
The UVCH is something like GP, GP, I, I, G, I, I, GP, GP
GP== Glow plug
I == Injector
G==Ground
I had an IDM go out with the same result, but mine was corroded and looked as though it had sat in a puddle of water for a while so it was a lot easier to figure out why. In your case, its good to make sure the connections are solid so you don't risk burning another idm out.
Disclaimer: There are many other people on here with MUCH more expertise than I have and I hope they post if I'm saying anything off base.













