I have a Crank no start. Before I took it into the shop it ran, only on one side. Started within 15 seconds of cranking everything time cold or warm. Limped it over to the shop never dying. Shop finds short in #5 injector, replaces it with known good used injector. They told me they got it running good, no rough idle and sounding healthy for about 20 minutes then it died. After their diag they recommended that I change the hpop and ipr. Brought the truck home (on a tow truck) and when I got home I tried to start it, could never get it started, sprayed a little starting fluid and it started for no more than 2 seconds then fell flat. Replaced hpop and ipr valve. Filled oil reservoir on top of pump to about an inch from the top. Let diesel fill up in fuel bowl and started cranking, and cranking. Couldn’t get it to start. I also thought maybe the #5 injector had bad orings since they kept the used one in there and I never had that problem of it dying when it was warm before taking it in. Changed cps, put half a tank of diesel in it, fresh new batteries and still no start. Made sure tin nut was tight on ipr valve. Ran buzz test and all buzzed good. Found small fuel like but fixed it and nothing changed. Monitored my values on my scanner. Icp got up to 315 psi, ipr made its way to 64%. Icp voltage didn’t go above .630 volts when cranking, is that normal?Where should I look next, is there anything I’m missing?

 

The injector driver module get tested at the shop?

 

Yes, they put in a known good idm to test

 

Oh boy. And you for sure didnt have water in fuel. Fuel bowl isnt clogged and the filter is good. And they did get 20 minutes of actual proper running. With oil pressure working. And it will ether start. And all the known culprits have been changed. I'm stumped and we need opinions from diesel techs now.

 

Judging by the ICP voltage reading, it looks like an actual low ICP problem. It could be any of several things. Defective IPR valve, or possibly unpowered, but that's not very likely at this stage. A major leak in the high pressure oil system, such as injector o-rings. Could also be a bad high pressure pump, but that's usually the last thing I suspect. What are you using to get your data, ForScan?

 

Im using an Icon T7 scanner. I do have new orings for it, but I’d rather test everything before resealing all of them. Someone on Facebook in a 7.3 group said I should send 12v to ipr and check that, then deadhead the system.

 

You can try powering the IPR directly with 12v for a couple minutes. The connector is the same as the connector on a fuel injector. If you happen to have an old valve cover harness laying around you can steal a connector from it and use that. If you have the right fittings, you can deadhead the pump into a 3000 psi gauge or adapt it to an ICP sensor and see what kind of pressure it's building. You can also supply compressed air to each head's high pressure oil rail and listen for any blown o-rings to start farting out air . . .

 

okay, out of those tricks, what would you recommend I start with first?

 

Since I do believe the IPR is being powered and the ICP voltage and pressure readings correspond, the more likely issue is a leak. Because of that, I'd start with the compressed air. You can use a rubber tipped blowgun pressed into the HPO hose fitting to prevent any blowback from coating you. Keep a rag over it so you don't wear the oil if it blows back. Or you could possibly find an adapter from the o-ring boss threads on the head to NPT for an air fitting.

 

My 7.3 crank no start was vexing. Turns out the under valve cover harnesses had failed. The harnesses power the glow plugs and send signals to the injectors to fire. It's a known issue. They shorted out 2 glow plug solenoids. The under cover harnesses should be replaced every 10 years.

 

With only 315 psi ICP as the OP has, the valve cover harnesses don't even come into play.

 

So I got it started and to be quite honest I’m not sure what I did. I tried putting compressed air into oil rail but it blew everywhere like you said, well into the rag. Finally gave up on that cause it kept coming out. Had both valve covers off, cranked and cranked and finally it wanted to catch on… monitored the icp and it finally was getting over 500 but my batteries were under 10.5 when cranking. Charged them up and it started. Ran at about 780-795 rpms then it dropped down to ~700rpms. Ran cylinder contribution test and got Cylinder 1,3,5,7 Contribution/balance codes. Icp at idle was from 460-622psi on one and 516-565psi on the other. Not sure why there’s 2 different readings for Icp. Both valve cover harnesses are new, engine harness is new. I’m stuck where I should look next.