7.3 starting issue

Dentside diesel

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Hello Idi lovers. I have a 1990 7.3 and my truck has always run flawlessly. But as of lately when it’s warm and intermittently the truck will fire once and die two times then it will start normally and run perfect. Now most people tell me I am getting air in the system but why will it not do it overnight and sometimes not even at all? Any ideas. The pick up pump only has about 4000 miles on it Replace fuel filter not long ago Fuel return line and caps and O-rings Replaced same time as pick up pump. No leaks
 

Nero

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Could be the injection pump is on its way out. Next time it does it, try the warm water trick.
 

Dentside diesel

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We just had a major heatwave in Northern California A couple of weeks ago And even in the heat of the day it was still very intermittent. I would think if heat was affecting it it would do it more often. Isn’t there 100 different things I could do before I replace my injector pump?
 

Nero

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I had a return line that would bleed down, and cause a similar situation, but only on cold starts. Fire up, run fine for a sec, then die. Could be that you have a leak when it's warm, and things have expanded. How are your fuel return line olives?

Also, I suggest to try the water trick first before replacing the pump. No way I'd suggest replacing big $$$ right out the door
 

Dentside diesel

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You mean are they leaking? There are no leaks that I can see. The weird thing is that when i have an issue the truck actually fires on first crank and I let off the key but it doesn’t start. Then I try again same thing. Third time it starts and runs fine. No abnormal cranking.
 

IDIDIDIhoDhoDhoDO

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Does kind of sound like air intrusion. I'd wipe the valley pan as clean and dry as you can get it and also the exterior of the injection pump. Then keep checking it over time and see if you're weeping fuel from anywhere. Ever done the seals in the hard line from the fuel filter to the injection pump?
 

Dentside diesel

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No I haven’t. Haven’t had a reason. Can’t ever have to many new seals I’ll take all your advice and clean everything up and keep an eye on it.
 

Nero

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It won't be an external fuel leak, more like it bleeds fuel back to the tank, then the fuel return lines leak air in.
 

Brian VT

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I just went through the no warm start, water on the injection pump to get it to start, replace injection pump deal. That doesn't sound like what you have. That's good news for you.
 

Jesus Freak

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We just had a major heatwave in Northern California A couple of weeks ago And even in the heat of the day it was still very intermittent. I would think if heat was affecting it it would do it more often. Isn’t there 100 different things I could do before I replace my injector pump?
There's obviously 100 other things, but pouring Luke warm water on the IP to see if it consistently makes your engine start is a pretty inexpensive and non technical diagnostic.
It won't be an external fuel leak, more like it bleeds fuel back to the tank, then the fuel return lines leak air in.
There's a check valve in the mechanical fuel pump that can cause fuel bleed down too. I've had that happen and create a similar issue.
 

Dentside diesel

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OK everybody I’m following up because nobody EVER does. I had a friend who is a Diesel mechanic tell me that it sounded like my fuel shut off solenoid was losing power. So I ran a jumper wire from the battery with an in-line fuse block and shoved the wire down in the back of the plug going into the Solenoid. For a couple days I didn’t have any problems but eventually I tried to start the truck and it was doing the same thing. I got out of the truck and installed the fuse in my jumper wire and the truck fired right up. But upon doing that I smelled some wires getting toasty. So at least I know it’s not the engine or its components. But on the bad side I have an electrical problem to find. Thanks for everyone’s suggestions I did learn a couple things.
 
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