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Discussion Starter · #1 ·
Backstory: Father-in-law purchased a 1999.5, F-350, 7.3L in 2015. He purchased it in the summer and uses it mainly to tow his giant fifth wheel all over God's green earth but sometimes he uses it to for his daily driver, especially in the winter. The winter of the year he bought it he noticed in order to start it in anything under 40°F he had to cycle the key through the GP indicator light cycles three or more times. Assuming the problem was just thick oil and the engine being extremely cold-blooded he decided that this wasn't an issue and lived with it. Fast forward to 2018 on a very snowy crap of a day, he jumped into it after work and the thing wouldn't start no matter how much he cycled the key until he finally killed the battery. He plugged the heating system into a jump box for an hour and jumped the battery with another truck and was finally able to get it home, needless to say, by the time he was done he was extremely frustrated. Up to that point he'd never had to plug it in, since then he has plugged the heating system in every time the temp gets below 50° F but the hard start has gotten progressively worse and now he will not take it somewhere he can't plug it in after sitting for 30 minutes or more. Also, he is now required to cycle the key three-plus times any time he starts it under 40° F no matter when the last time it ran, 10 seconds or 30 days.

Forward to fall 2020 and it is sitting in my driveway as I am trying to replace the dreaded sloppy steering gearbox. It's about 37°F outside, not knowing about the cold start issue I attempted to start it and it wouldn't. After getting the backstory from him I decided to look into it and have gone down a three-month-long rabbit hole with this thing. I've rebuilt the HPOP, IPR, changed the oil lines, changed the glow plugs, GPR, and purchased an AutoEnginuity scanner from RiffRaff.

I NEED HELP! I am still having the issue, I recorded the Engine RPM, ICP pressure (PSI), ICP (Duty Cycle), ICP (Voltage), Vehicle Speed, and for ****s and giggles the Coolant temp data from an interstate drive and would like to have someone that knows what the heck they are looking at take a look at it.

Idle
ICP Avg = 511 psi
Duty Cycle Avg = 13.83%

Cruise 60-80 MPH
ICP Avg = 1819 psi
Duty Cycle Avg = 29.12%

ICP Range = 415.75 - 2746.78 psi
Duty Cycle Range = 10.94 - 40.62%

Please let me know if you want the report.

Any assistance would be greatly appreciated as I am at my wit's end with this thing!
 

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You certainly have put a lot of work into it. You are describing an engine that will run, but has starting related issues below a thermal threashold. Typically one will start with confirmation of battery condition, alternator capability, connecting cables, glow plug solenoid and starter speed. If the starting system doesn't get to its ECM minimum permissive speed, and still have enough voltage permissive, it wont/cant start ever. Lower temps cause would worsen the condition. Easy way to check the starting speed. Takes two people, put reflective tape on a spot on the front crank, get where you can direct a laser tachometer on the crank tape trigger and have your helper start it over while you read the speed, If it doesn't get to 100 RPM it wont start. I use a Monarch 204 laser tach with "peak hold" and TT signal, its a bit pricey just for this test but I use it for other analysis. One can buy a good laser tach for 75 bucks good enough for automotive and HVAC.
 

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Your ICP and IPR duty cycle number look fine to me. BTW, the ECT that AE shows isn't valid on a 7.3L pickup, as that isn't reported to the PCM, just the temperature gauge on the instrument cluster.

Your AE will check cranking RPM easy enough. If your glow plugs are up to snuff, then a hard/no start when cold could be a starter that's on its way out and can't crank fast enough. Or the engine compression is just too low from piston ring wear. You didn't mention the mileage, but it's possible the engine is plain worn out (but I haven't heard of that many 7.3Ls having that problem.)

One other thought is that the injector clearances are too close and with cold oil the solenoids can't pick up the armature plate. There are shim kits available to correct that issue. Try running an injector buzz test when the engine is cold and listen closely to the sound the injectors make. If it's not as loud as a buzz test run with the engine warmed up, then the injector clearance could be your problem.
 

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I would say it is the starter drawing too many amps, when that happens the injectors won't fire properly/won't turn fast enough to start. Had that issue more than once (even had starter check good at NAPA still had issues). A good starter will spin the motor FAST. Almost never the HPOP so people stop replacing/rebuilding them!! Check the alternator output when running also. Make sure you are getting around 14 volts, you can loose a diode that will lower the voltage but not trip the light and the batteries will run down over time.
DENNY
 

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Sounds like what happened to mine. The end result? Worn injectors (did the shim kit), shot glow plugs (new ones), and an oil change. Forgot to plug it in and we were about 15 F here the other day, cranked right up after one GP cycle.
 
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Discussion Starter · #6 ·
BTW, the ECT that AE shows isn't valid on a 7.3L pickup, as that isn't reported to the PCM, just the temperature gauge on the instrument cluster.
I was curios about why this was showing such odd numbers! Thank you!

I'm sorry, miles would be a pretty important part of the puzzle. The truck has 177K, still a baby and I wouldnt think it should be having this many and type of issues.

After reading other threads I have suspected that the starter could possibly be an issue but to me the thing sounds great. I may just bite the bullet and buy a new one just to see what it does. I am gathering all of the equipment required to complete a compression test and will post those results soon. What numbers am I looking for on this engine? I have seen threads that state as high as 410 and as low as 200 psi with a 5-25% difference between all cylinders. Needless to say that is quite a range that could result in an unnecessary rebuild if wrong.

I did a buzz test right after I ran it for the data I provided in the attachment. I had no idea what I was listening for and it checked out to dumb ears. I have done some youtube mechanicing now and have a better idea of what I am listening for. I honestly wouldn't be surprised if at least one injector is shot.
 

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Ford's go/no go criteria for compression tests is that the lowest has to be within 25% of the highest, so if your highest was 400 psi, the lowest on a "good" engine should be no less than 300 psi. Every 7.3L I've checked has been in at least in the high 300's, and one read just over 400 on all cylinders.
Unless you've had serious issues with air filtration, I doubt you'll see an issue with compression.

If you're going to check them, do it with all the glow plugs out and crank using the starter solenoid on the passenger side fender, NOT the key. If the injectors are activated, you may get REAL HIGH pressure.
 

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Backstory: Father-in-law purchased a 1999.5, F-350, 7.3L in 2015. He purchased it in the summer and uses it mainly to tow his giant fifth wheel all over God's green earth but sometimes he uses it to for his daily driver, especially in the winter. The winter of the year he bought it he noticed in order to start it in anything under 40°F he had to cycle the key through the GP indicator light cycles three or more times. Assuming the problem was just thick oil and the engine being extremely cold-blooded he decided that this wasn't an issue and lived with it. Fast forward to 2018 on a very snowy crap of a day, he jumped into it after work and the thing wouldn't start no matter how much he cycled the key until he finally killed the battery. He plugged the heating system into a jump box for an hour and jumped the battery with another truck and was finally able to get it home, needless to say, by the time he was done he was extremely frustrated. Up to that point he'd never had to plug it in, since then he has plugged the heating system in every time the temp gets below 50° F but the hard start has gotten progressively worse and now he will not take it somewhere he can't plug it in after sitting for 30 minutes or more. Also, he is now required to cycle the key three-plus times any time he starts it under 40° F no matter when the last time it ran, 10 seconds or 30 days.

Forward to fall 2020 and it is sitting in my driveway as I am trying to replace the dreaded sloppy steering gearbox. It's about 37°F outside, not knowing about the cold start issue I attempted to start it and it wouldn't. After getting the backstory from him I decided to look into it and have gone down a three-month-long rabbit hole with this thing. I've rebuilt the HPOP, IPR, changed the oil lines, changed the glow plugs, GPR, and purchased an AutoEnginuity scanner from RiffRaff.

I NEED HELP! I am still having the issue, I recorded the Engine RPM, ICP pressure (PSI), ICP (Duty Cycle), ICP (Voltage), Vehicle Speed, and for ****s and giggles the Coolant temp data from an interstate drive and would like to have someone that knows what the heck they are looking at take a look at it.

Idle
ICP Avg = 511 psi
Duty Cycle Avg = 13.83%

Cruise 60-80 MPH
ICP Avg = 1819 psi
Duty Cycle Avg = 29.12%

ICP Range = 415.75 - 2746.78 psi
Duty Cycle Range = 10.94 - 40.62%

Please let me know if you want the report.

Any assistance would be greatly appreciated as I am at my wit's end with this thing!
Sounds to me like only one battery is connecting. It needs two to start unless it's a really nice day. Clean all the battery posts and scrape connectors on wires to the starting solenoid. Check the voltage on the cables, not the battery posts.
 
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