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yes icp reaches 500+ psi when cranking, it will take a while to build up only if I haven’t tried cranking for a bout a week or so. I’m assuming because the hpop res bleeds back down into the oil pan?
yes, I actually just installed a noco 2a battery tender. I plug it in after doing any testing to ensure batts are charged next time
When I listen to other people’s trucks with 7.3l (customers, friends and neighbors) mine sounds sluggish compared...but it sounded the same next to my buddies when running at idle.
Yes, I believe so. I filled the fuel tank full when I went camping and never went below half by the time it got towed home. It’s a big tank, I think 60 gallons. I can always double check though
Ok , the hpop res should not leak down, it should stay about 1/4-1/2 if inch below the fill plug on top of hpop. You said you already checked this but was it after cranking or after the truck has sat for a while? I would check the hpop res level tonight to make sure it is full, then let the truck sit overnight and check it in the morning to see if hpop res is still full. If it has leaked down then that is most likely your problem. Just to be sure you did replace the CPS or any other sensors with only motorcraft parts correct?
Is there any kind of tuner or chip on the truck or is it completely stock? Just trying to rule out all the basic stuff first. I remember there was a guy at wild back that had very similar symptoms to yours and it ended up being the IPR even though there was no code for it. I have never done it before but I believe there's a way to test the IPR with a DVM so you might want to look that up since it is a free test.
Ok , the hpop res should not leak down, it should stay about 1/4-1/2 if inch below the fill plug on top of hpop. You said you already checked this but was it after cranking or after the truck has sat for a while? I would check the hpop res level tonight to make sure it is full, then let the truck sit overnight and check it in the morning to see if hpop res is still full. If it has leaked down then that is most likely your problem. Just to be sure you did replace the CPS or any other sensors with only motorcraft parts correct?
The hpop was full in my initial post after cranking. It had leaked down while I was trying to figure out how to fix the bus (sat for about a month)
left the shop for the night but I will check in the morning, I had cranked it over today to find the icp value while unplugged. Tomorrow should be good indicator of hpop leaking down or not
I replaced the CPS only and I bought it from oreillys (next door to my shop) it’s the black one with the purple plug. I kept the original CPS just in case.... (grey/tan cps)
I read somewhere that the hpop res will leak down EVENTUALLY but takes some time indeed.
When trying to diagnose hpop res leaking, what steps do I need to take and where/ why would it leak down??
Last edited by LegalizeChey; Mar 2, 2022 at 07:17 PM.
Have you tried a buzz test of the injectors? You have pretty much covered everything else that I can think of. And I was wondering if your turbo was frozen up or binding so it sounds like you've checked it and it seems OK.
Have you tried a buzz test of the injectors? You have pretty much covered everything else that I can think of. And I was wondering if your turbo was frozen up or binding so it sounds like you've checked it and it seems OK.
yes I did a buzz test, test came back good and injectors sounded consistent between all 8
Was just reading through the Ford created no start chart and it says fuel pressure is a minimum 45 psi. Not sure why the other flow chart says much less, but could be your fuel pump getting weak. It's free to check and clean battery connections and ground straps first. Bad grounds and battery connections will cause the trucks to do all kinds of things. Also just in case your fuel pressure gauge is faulty you can run a hose up to your fuel bowl drain pipe under front passenger side of engine, run the other end of hose into bucket , turn the ignition to on with the fuel bowl drain valve open and watch to see it you have a good solid steady flow of fuel going into the bucket
Was just reading through the Ford created no start chart and it says fuel pressure is a minimum 45 psi. Not sure why the other flow chart says much less, but could be your fuel pump getting weak. It's free to check and clean battery connections and ground straps first. Bad grounds and battery connections will cause the trucks to do all kinds of things. Also just in case your fuel pressure gauge is faulty you can run a hose up to your fuel bowl drain pipe under front passenger side of engine, run the other end of hose into bucket , turn the ignition to on with the fuel bowl drain valve open and watch to see it you have a good solid steady flow of fuel going into the bucket
will look into fuel pressure again, I may have noted the wrong psi. As I was just trying to remember everything off the top my head while making the thread. I hadn’t tested the pressure in over a week and had lost my notes...so I will reconfirm
Originally Posted by Njstern87
Loss of power, increase in temp, and black smoke scream turbo/fuel problem to me.
You said you checked turbo and it spins freely, so that leaves fuel or a blockage on the intake system someplace.
Per all-data here are the fuel pressure specs:
I can take the turbo off no problem. What should I be looking for? Working in the vans is actually kinda nice cause I get front and rear access to the motor because of the dog house...so turbo removal and inspection is not tough.
Again, I will confirm fuel pressure first. Should I make up a dead head tester to test pressure directly out of fuel pump? Also is a lift pump common in the fuel tank for Diesel engines? I’m not sure, I haven’t thought of that until now.
I have no doubt the turbo could have caused the problem when the op was driving and smoke was bellowing but would that have anything to do with the no start condition? Was thinking get the truck started and go from there. I have personally not had any problems with the turbo other than taking it out to rebuild it so I could be wrong here just asking. I think another clue to this dilemma is that the op was able to get the truck started after it broke down and got towed, was able to drive the truck for 30 minutes and then just shut down.
I agree, from my perspective it’s unrelated to why it flat out wouldn’t start after. Unless it was something catastrophic internally, but everything is turning without concern...
checked the hpop res this morning it is indeed empty.
I agree, from my perspective it’s unrelated to why it flat out wouldn’t start after. Unless it was something catastrophic internally, but everything is turning without concern...
checked the hpop res this morning it is indeed empty.
Okay so now fill it up, try cranking for a while and then check the h-pop res again. If it is empty again then your l pop could be bad or you have a crack in your oil pick up tube in the pan. Let's hope it is the lpop. Could also be your Rez leaking down quickly but I would think if the lpop was functioning properly it would be able to keep up with that.
You can also try to keep refilling the h-pop res and see what happens( try to keep cranking to start it). Truck will run pretty rough at first as there is air in the system
Read through this quickly. (Yesterday I read your original great post but was waiting on someone with real answers to pipe in).
The comment I hopped on to post was already mentioned by Njstern87. I was wondering if something blocked the air flow to the turbo. Can you check the intake to make sure it’s not plugged with mouse nests etc? Maybe try to start with disconnected from turbo as a quick, easy check?
The other guys have you headed in good directions on all the other stuff.
Read through this quickly. (Yesterday I read your original great post but was waiting on someone with real answers to pipe in).
The comment I hopped on to post was already mentioned by Njstern87. I was wondering if something blocked the air flow to the turbo. Can you check the intake to make sure it’s not plugged with mouse nests etc? Maybe try to start with disconnected from turbo as a quick, easy check?
The other guys have you headed in good directions on all the other stuff.
intake has been disconnected for weeks. But I will check the intake tube and resonator box. I keep a rubber cover that fits over the turbo when I’m not working on it....
Okay so now fill it up, try cranking for a while and then check the h-pop res again. If it is empty again then your l pop could be bad or you have a crack in your oil pick up tube in the pan. Let's hope it is the lpop. Could also be your Rez leaking down quickly but I would think if the lpop was functioning properly it would be able to keep up with that.
You can also try to keep refilling the h-pop res and see what happens( try to keep cranking to start it). Truck will run pretty rough at first as there is air in the system
So if I crank over right now (empty hpop) with my scanner watching icp psi. I can watch it build pressure from 0 to 100, 200, 300 all the way up to 500/600psi. If I check reservoir after doing this it will be full. (And I will double check this along with fuel pressure)
Could the check ball be the culprit?
Why would a cracked pickup tube cause problems with the hpop reservoir? I thought that only supplied the LPOP?
And bad LPOP means not enough oil/pressure to supply HPOP res? Keeping it starved?
Unfortunately works busy the rest of the week and a busy weekend coming up. Earliest I can perform these tests will be Monday evening after work. So bare with me if things slow down in this post...
And I want to thank you all for the fast replies. I tried two other “ford” or “diesel” enthusiast forums and got 0 replies after multiple posts. Y’all really are enthusiasts, and have confirmed all my thinking and work so far. Very grateful thank you all. And can’t wait to get to the bottom of this...
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