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7.3, no start when hot: need clever ideas

7K views 28 replies 8 participants last post by  1995ps 
#1 ·
Starts up fine after cooling for 1-2 hours or if you kill it and start again immediately. If it sits for 30min or so it will crank like mad but never start.
Thanks for any help.
 
#6 ·
Thanks, that is what I was thinking, will I get any codes? I have been meaning to scan it. I switched in a * 17 hpop and it had the ipr on it, only about 2-3K miles ago.
If the o-rings are bad can i tell by oil on the outside of the sensor?
Thanks
 
#7 ·
No codes. Just pull the IPR and look at the o-rings on the end, I would just go ahead and get replacements before you do the job because if nothing else they need done anyway.
 
#8 ·
Put on the ipr solenoid from my original hpop. Test drove till hot, died and would not start. Towed it home, put on the whole ipr from the original hpop. Still won't start, last time it had to cool for six or seven hours. Hooked up the super chips scanner and got 02-p0113 high air intake temperature (tymar style intake and I removed the sensor that was in the air box???)
01-p0340 cam sensor
cleared codes
I reset the truck to stock, still wouldn't start.
So do I still buy an ipr??? Or is it something else?
Thanks for help.
 
#12 ·
Idk now, worked fine till last night I ran to the store killed it while I went in then it wouldn't start. Left it for a little over an hour and then it started. Something to note it almost always takes 30seconds + of cranking usually two times to start, has only started immediately a handful of times. No codes now. I pulled the IDM and checked the harness all ohm tests seemed to be right although only 1-1.5ohms when it called for 2.8-3.6 don't know if I trust my meter. Opened the IDM and it looked perfect. Anyone now how to test it (the IDM)? Or any other ideas. Thanks
 
#13 ·
To note, when you turn the key on battery light is on and voltage is at 10-11, maintains while cranking and after start up. Revving the engine will raise voltage slightly, after a minute or so the gauge flickers for a while then pops up to 14volts or more and stays there.
Also had a battery charger on the truck not showing full charge, when I pulled the IDM it went to full charge, plug it back in and showed needing a charge.
:dunno:
 
#17 ·
This is normal, because the glow plugs are on and it's keeping battery voltage down till they kick off.

I agree with the injector o-ring problem. Most of the times when you have a no start hot it's a high pressure oil leak issue. As the oil thins out when it heats up it will cause any high pressure oil leaks to be worse. You can try and pressurize each head to isolate issue, or just go ahead and pull all the injectors and replace the o-rings.

The only weird thing is the cam sensor code. After you did the cam sensor it was fine for awhile? Have you had a chance to recheck codes?
 
#15 ·
You could have injector orings bad creating the same problem. We had that on a 97' that did the same thing.Air pressured the cylinder heads and found them blown.
 
#16 ·
I have a 95 PSD that did same thing and went through everything you did my problem was in the fuel tank the strainer had busted up and plastic pieces was getting sucked up in the fuel lines and wedging stuck. How much fuel you got in the truck right now? Cause I noticed mine doing it at quarter tank left.
 
#18 ·
Thanks for the replies I will try the coolant temp sensor if it's in fail again as that is easy.
I keep reading it and only get the p1111 code for A OK.
Fuel pressure check is on my list.
How do I pressurize the heads for that test?
I was also thinking about a better scanner such as AutoEnginuity OBDII OBD2 Windows Scan Tool Scanner(USB) Auto Enginuity | eBay as I only have the superchip scanner.
Thanks again
 
#19 ·
I'm assuming it's a 95 truck based off your name. If so, it doesn't have a coolant temp sensor. The PCM didn't read coolant temp on the 94-97 MY engines and based all readings off the oil temp sensor.

Fuel pressure check should be done just to eliminate it off the list of probable issues.

Best way to pressurize the high pressure rail in the heads is to warm the truck up till it won't start, pull both valve covers, disconnect the oil feed line going into the rails, then use a rubber tipped air blower to apply air pressure into each head. There should be no leaks around the injectors.

A good scanner would help out a lot. At this point I am just guessing it's a high pressure oil issue based off your symptoms. If you had a scanner I would tell you to monitor ICP pressure when it's acting up and see what it's reading. That would tell us real quick if that was your issue.
 
#20 ·
Yes is a '95
Where are the oil temperature and icp sensors located?
Thanks, I will try pressurizing the head when I get a chance.
I have read that unplugging the icp will default the pressure and help it to start is that true and if so what would it prove?
Thanks again.
 
#22 ·
Oil temp is located on the back side of the high pressure oil reservoir. ICP is located on the drivers side head across from the fuel filter housing. Do a google images search on ICP sensor and it will pop up.

Unplugging the ICP sensor will cause the PCM to estimate ICP values. The only purpose of unplugging the ICP sensor is if you have a goofed up ICP sensor. If the sensor is reading wrong and telling the PCM it isn't building enough pressure, when it actually is, it will cause a no start condition.

Look for signs of oil in the end of the ICP connector also. Usually when they start to go bad they will push oil thru the sensor.
 
#23 ·
Well top of the morning to ya.
I have a 2000 7.3 in a 350 4x4 and after reading your posts, I have the same problem that just started the other day. Starts fine, runs great and then just quits, wait five min and off it goes again for another day or so or maybe an hr. Ya never know. I have three of these trucks and only one doing it right now. Only 150,000 for miles.
I need to know where all these sensors are, and the scan tool plug in doesn't have any power to it?.
HELP

Scallywag
 
#24 ·
Check your fuses. You'll probably find the one for the cigarette lighter blown. This fuse also supplies power to the diagnostic connector. Replace that and you should be able to communicate with the PCM.

Do you have a way to check codes? Almost sounds like a cam sensor issue. If it is you should have a logged p0340 code.

When it dies and wont start do you see the tach show RPM's while cranking? If it doesn't then it's definitely a cam sensor issue.
 
#25 ·
I've got a massive fuel leak on mine now on top of the motor. I'm guessing the line that goes to the bottom of the fuel bowl? I can't see that end, I got a fuel pressure test gauge , all the o-rings for the fuel bowl and the irp o-rings. This time when I pull the bowl I'm going to clean it all up do the o-rings check fuel pressure cold then hot. Then if it's good do the air pressure test in the high pressure oil lines.
 
#26 ·
Hmm, did it just happen all at once? Could be many different things around the fuel bowl. I'd try and clean it up good and see where it's coming from. I've seen the bottom of the filter housing corrode out and leak, or the wiring connectors for the water in fuel and the fuel heater can leak. Also the fuel pump has a weep hole and can leak fuel out.

I'd make sure you find out where it's coming from before replacing anything.
 
#27 ·
intermittent stop.

Capt Joe.

With the AE scan tool hooked up after 2 hrs running it stoped. I imediately tried to start while looking at the HOP was like 100psi and duty cycle for the IPR was at 40. So the system was telling the IPR to produce pressure but it was sticking, need 500 psi min to start/run.

Replaced the IPR and now have good HOP and no problems.
 
#28 ·
So I was missing the o-ring between the fuel bowl and regulator, must've dropped it last time I pulled the fuel bowl, found it in the valley.
Cleaned up everything, all new o-rings on the fuel bowl, new hoses, new filter, broke the stand pipe, so new stand pipe tossed the fuel bowl heater plate and all. New o-rings on the irp. Now fuel pressure swings rapidly back and forth from 48-55psi at idle at 2000rpm swings from 40-70psi (both the needle moves so quickly you can hardly tell where it is).
Still super long crank to start and now for the first time no wait to start light.
 
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