Hot Tow, now hot starts.

[narmalee]

So, after going to get a '96 7.3 extended cab two weekends ago,
noticed something odd after the trip, about 600 miles of towing right at 1,000* the whole way thanks to a headwind

I was at 2500 miles on my oil change before the trip,

a warm restart can have up to 4 seconds of cranking and the LPOP isn't getting oil that whole time (watching mechanical oil pressure gauge). After it starts, it surges to 900 rpm for just a moment, and then settles back down to normal 600.

Cold restart after like 4hours of cooling, it fires right up normally after a second of cranking.

Hot, 5-10 min wait: is almost a no start, mechanical gauge shows it sitting at 16-20 psi of oil the whole time after about 5-10 seconds of priming. Maybe 30 seconds of cranking or more, feels like forever.

Changed oil this morning, no change in this behavior, and now im worried... this is my work truck and now im chasing an issue

The motor was rebuilt about 20k miles ago due to the original owner dusting the engine down horribly, up to this point the engine has run just fine, hot or cold and hot/cold restarts

oil pressure hot is about 28 psi, 53 cruising, this has been the same before the trip, and after

unplugged ICP, performed restart, same rough start
unplugged engine oil switch in HPOP cover, same rough start
tin nut is tight on on the IPR, IPR is tight

Hoping someone with some prior understanding can chime in on this, but this sure seems like oil drainback/bypass to me, or heaven forbid the pickup tube cracked. I did check it before the rebuild and it looked perfectly fine, but that WAS 20k miles ago.

Im going to start by checking the check valves and drainback valves, then move to the LPOP Melling pump, glad i kept the OEM pump that had 68k on it now... hoping its just some trash that the heat dislodged and is jamming the bypass or checks open letting oil bypass

please help with any advice other than buy a chevy :3

THANK YOU!

 

[greenskeeper]

check oil level at the HPOP inspection plug. Oil should be no more than 1" from the top. More involved diagnosis would be to remove the valve covers and watch the injector oil spouts when cranking. There should be even flow from each spout indicating that the injector is firing properly.

 

[narmalee]

yeah, Hpop levels were fine, nothing on the injectors are going to be firing if I don't have low pressure oil conditions met first tho… im suspicious the galley plugs in the back of the block, at least one of them might be blown out, guess pulling the engine is in the future,

I needed to pull it anyway to seal up the pan leak for good, plus a rebuild on the ZF5... good 4 day weekend job I guess... -.- at least I have access to a lift

 

[greenskeeper]

yeah, Hpop levels were fine, nothing on the injectors are going to be firing if I don't have low pressure oil conditions met first tho… im suspicious the galley plugs in the back of the block, at least one of them might be blown out, guess pulling the engine is in the future,

I needed to pull it anyway to seal up the pan leak for good, plus a rebuild on the ZF5... good 4 day weekend job I guess... -.- at least I have access to a liftIf the HPOP is full and the LPOP isn't supplying any oil, the engine will start and run for about 10-30 seconds on the HPO reservoir. If the galley plugs are "blown out" you would be dumping a huge amount of oil in a short time.

If the HPOP is full, and the LPOP isn't supply any oil to the reservoir, the engine will still start and run for 10-30 seconds on the oil that is in the reservoir. If the galley plugs are "blown out" you would be dumping a large volume of oil all over the engine bay.

the LPOP lubricates the engine and supplies the HPOP with oil. If the LPOP isn't working correctly the injectors would still fire and empty the HPOP reservoir since the HPOP supplies high pressure oil to fire the injectors. If the HPOP is full then the LPOP is working.

 

[narmalee]

If the HPOP is full, and the LPOP isn't supply any oil to the reservoir, the engine will still start and run for 10-30 seconds on the oil that is in the reservoir. If the galley plugs are "blown out" you would be dumping a large volume of oil all over the engine bay.

the LPOP lubricates the engine and supplies the HPOP with oil. If the LPOP isn't working correctly the injectors would still fire and empty the HPOP reservoir since the HPOP supplies high pressure oil to fire the injectors. If the HPOP is full then the LPOP is working.

Ohhh, i was under the impression it wouldn't start at all until the lpop had adequate psi

So, im chasing the opposite then it sounds like

And im probably calling them incorrectly, the plugs behind the cam cover plate in the rear that feed the mains

 

[greenskeeper]

Ohhh, i was under the impression it wouldn't start at all until the lpop had adequate psi

So, im chasing the opposite then it sounds like

And im probably calling them incorrectly, the plugs behind the cam cover plate in the rear that feed the mains

need to zoom back so I can reference what you are pointing at

I'd suggest pulling the valve covers (or at least one of them) and confirm that oil is coming from the spouts on each of the injectors while cranking. No oil means the injectors are not firing.

 

[narmalee]

need to zoom back so I can reference what you are pointing at

I'd suggest pulling the valve covers (or at least one of them) and confirm that oil is coming from the spouts on each of the injectors while cranking. No oil means the injectors are not firing.

10-4, spent all day today doing my little grocery getter S10... somehow managed to take 10 hours to do a rear main seal on it... ON A LIFT... whole thing was saturated in oil and grime from old owner and tons of it had to be blasted and cleaned off before I could even get at bolts

im used to a '94 4.3 v6, this one is a 4 cylinder, easier right? far worse... everything was a PITA on it

but good thing, it seems to be 100% now, no leaks and even driving, which considering it has 245k on it, I was very leery about changing the tranny fluid... you know how that goes -.-

 

[narmalee]

Back to the 7.3 after the s10 drama lol...

So i checked the hpop reservoir, oil level ¾ of an inch below the oil sender unit when i pulled it out

On a thought, pulled the ICP and there was oil under the connector, totally saturated... so now im guessing its sensor related

I have a new ICP and IPR, so ill try a unit, see what that does, and maybe just go ahead and change the original IPR, yeah its low milage, but its old... I'll still hang onto it tho

 

[narmalee]

Just found this thread after searching: [relationship between IPR and the ICP]

for anyone interested or having issues
Sure fits my problems to a T

What's the relationship between the IPR and ICP sensor - Ford Truck Enthusiasts Forums

1999 - 2003 7.3L Power Stroke Diesel - What's the relationship between the IPR and ICP sensor - What is the role played by both the IPR and the ICP sensor and the relation to each other? I just replaced my ICP sensor for the second time in about 6 months. Both times because it was leaking oil...

www.ford-trucks.com

 

[greenskeeper]

Back to the 7.3 after the s10 drama lol...

So i checked the hpop reservoir, oil level ¾ of an inch below the oil sender unit when i pulled it out

On a thought, pulled the ICP and there was oil under the connector, totally saturated... so now im guessing its sensor related

I have a new ICP and IPR, so ill try a unit, see what that does, and maybe just go ahead and change the original IPR, yeah its low milage, but its old... I'll still hang onto it tho

check the oil level at the inspection plug at the top of the HPOP (hex head plug), oil level should be no lower than an inch from the top of the housing

if the ICP connection has oil, the sensor is faulty. However, you can run the engine with that sensor disconnected and the PCM will default to a fixed oil pressure value... in other words that sensor will not prevent the engine from starting if failed or disconnected.

Did you remove the valve covers and confirm oil coming from all 8 injector spouts while cranking? That will narrow things down significantly if there is oil.... that means the injectors are mechanically/electrically firing and the problem is elsewhere.

 

[narmalee]

got the covers pulled... FINALLY...

no oil firing on any of them, which was what I was guessing because I had no smoke while cranking

and yes, that was with someone turning the key, not a starter bump button :3

its got to be what I posted, I have a brand new IPR im going to put in this weekend, its been sitting in the bag brand new... TIME TO GO TO WORK!!!!!

 

[greenskeeper]

Do you get the WTS light when turning the key to "on" ?

 

[narmalee]

honestly, I didn't pay attention to the WTS light when it was hot

will have to check, but I think so

 

[greenskeeper]

hot no-start can also be an IPR coil that fails when hot, then acts fine when it cools off.

 

[narmalee]

hot no-start can also be an IPR coil that fails when hot, then acts fine when it cools off.

Yeah its got a very light stumble/hiccup at low rpms you can deff feel, got a new ICP coming, will change it and IPR at same time, sucks cuz its a new ICP, only about 20k miles on it and oem motorcraft