Pre-Power Stroke Diesel (7.3L IDI & 6.9L) Diesel Topics Only

Hard Start, hot day, almost stranded again

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  #31  
Old 09-10-2014, 04:02 PM
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that is called air intrusion. it is a result of air getting into the fuel return lines, and letting the fuel filter drain back to the fuel tank. then when you try to start it fires up off the fuel in the injector pump and dies because the filter has air in it instead of fuel.
then you have to crank it over to fill the filter and injector pump back up.
 
  #32  
Old 09-10-2014, 05:07 PM
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I know, maybe I have a pump going out and air? I will see what it does tomorrow morning. If I just had a 600 HP CAT under the hood all would be well.
 
  #33  
Old 09-10-2014, 09:14 PM
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Originally Posted by tjc transport
that is called air intrusion. it is a result of air getting into the fuel return lines, and letting the fuel filter drain back to the fuel tank. then when you try to start it fires up off the fuel in the injector pump and dies because the filter has air in it instead of fuel.
then you have to crank it over to fill the filter and injector pump back up.
It does sound like air intrusion could be the issue. Check all of the return lines and olives for any seeps, check the fuel line and fuel heater and see if you can find any pinholes or leaky orings.

The air fuel ratio varies on a diesel depending on the RPM and load, the further the throttle is pressed the more fuel is injected into the cylinder. Diesels always run lean, the amount of fuel controls the engine speed.
 
  #34  
Old 09-11-2014, 03:06 PM
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Thanks.nnnnn
 
  #35  
Old 09-11-2014, 03:57 PM
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Originally Posted by Realslowww
So if it acts up push pedal to floor to get cold fresh fuel to help seal so pump will fire injectors?
you also hit the accelerator with the key on to get the high idle to pop out, if you dont touch the pedal the high idle plunger doesn't have the power to over come the throttle return springs, so no high idle
 
  #36  
Old 09-18-2014, 05:41 PM
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It did it again the other day, it's weird. Sometimes if I put my foot to the floor to start it it starts for about 2 seconds real quick then dies and is real hard to get back going.

It seems to do this when you start it with your foot to the floor on the pedal. I think I have air getting in ? the truck seems to run a little funny sometimes like the cylinders are getting air through the injectors.

Thanks for tips.
 
  #37  
Old 09-19-2014, 10:11 AM
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Originally Posted by Realslowww
It did it again the other day, it's weird. Sometimes if I put my foot to the floor to start it it starts for about 2 seconds real quick then dies and is real hard to get back going.

It seems to do this when you start it with your foot to the floor on the pedal. I think I have air getting in ? the truck seems to run a little funny sometimes like the cylinders are getting air through the injectors.

Thanks for tips.

That does sound like an air intrusion issue.
 
  #38  
Old 09-19-2014, 05:27 PM
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Originally Posted by fordtruckman838
That does sound like an air intrusion issue.

Thanks for helping out, I think my pump is worn as well as air is getting in . It goes fine but sometimes bang zoom. Eventually it will strand me probably so I should fix it.
 
  #39  
Old 09-28-2014, 02:11 AM
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My 94 does the same thing with not starting hot after sitting for a half hr to an hr. I'll try the water trick on the IP lines next time it doesn't start. When it doesn't start, I give it a little taste of silicone spray and it'll fire right up. I replaced the fuel supply line from the selector valve to the lift pump with new (diesel rated) rubber hose, so I don't think its air intrusion.
 
  #40  
Old 10-17-2014, 11:21 AM
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I had the same troubble on mine, changed fuel lines, injector-caps, locking clamps for fuel lines, o-rings on the injectors, and then i found out that the rubber hose that goes from the steel line to the mechanical lift pump whas old and rotten, changed all that, but for mine 7.3idi n/a e350 it turned out that it whas the starter that was shorted out inside, so every time i started it it drained all the juice out of my battery's i had maby 3-5 10 second turns on the starter on a hot day, but it turned out that the rpms at start was so low that i could not get a high enough fuel pressure to the Injector Pump and thats why i had many hard starts earlier, but after i swapped starter it starts every time.. and no need to charge the batteries 1every week too..
Leasson is if not enough RPM'S at start, not enough fuel and problems with compression and therfore hard starts,
And i know that if it is a very hot day, and the engine is hot the aftermarket glowplugs controller could act up due to the heat.
btw i can take pictures of the 2 and show what i mean

And it is important that the return line from the IP goes on the number 1 injector cap, for those that have the 90s and up
 

Last edited by polarbear87; 10-17-2014 at 11:32 AM. Reason: typo and forgot couple of things
  #41  
Old 10-17-2014, 11:32 PM
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I had a similar problem on my 87 F250 w/ 6.9L NA and it was the fuel tank selector valve letting the air in. I bypassed it and no problem starts every time I also put a check valve between the fuel pump and the filter. You might want to try it.
 
  #42  
Old 10-18-2014, 06:57 AM
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Originally Posted by RBerry9511
I had a similar problem on my 87 F250 w/ 6.9L NA and it was the fuel tank selector valve letting the air in. I bypassed it and no problem starts every time I also put a check valve between the fuel pump and the filter. You might want to try it.
I only have a huge single tank on mine, due to it was registered as a mini bus 9pas. Now it is only registered as a small truck here in norway since i drive trucks for a living and dont have a license for bus.. theyre really square about it here though... but i only had to take out the back rest for the 3seater in the boot if you know what i mean, due to the rest of the 3seater is an electric bed you cant take anyting else off...

Just wondering if the orginal thread starter got it fixed though ??
 
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