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7.3 liter diesel hard to start wont keep running

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Old 06-13-2018, 07:01 PM
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Default 7.3 liter diesel hard to start wont keep running

This is a 1993 f250 with 7.3 liter idi engine. Not absolutly positive but feel like I am getting air in the system from the return line system on the injectors ( I have seen this system called the injector lube system). My question is can I bypass this system at least long enough to get the truck and trailer 5 miles back down the road from my neighbors field where it has been the past two weeks.
 
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Old 06-13-2018, 08:48 PM
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An old trick was to install a clear line,, if the fuel was aerated, it was usually a pump fail issue.. If air was entering into a return,, fuel would generally be exiting..
 
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Old 06-16-2018, 12:25 PM
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Originally Posted by Hayapower
An old trick was to install a clear line,, if the fuel was aerated, it was usually a pump fail issue.. If air was entering into a return,, fuel would generally be exiting..
Replaced pump this morning. Still wont keep running stopped for awhile to allow starter and myself to cool down. Is it possible even though I have had it run for maybe five broken minutes to still have air on the injector side.
 
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Old 06-16-2018, 03:57 PM
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It does take a while for all the air to get out of the system.
Have you checked the oil reservoir at the top front of the engine for being full, it should be !!

Not knowing the condition of the vehicle, could there be a problem with the line from the tank to the pump and on to the hi press pump. Is the fuel filter housing in good shape and not allowing air to get in that way?

Are you getting any kind of smoke coming out of the exhaust when it is being cranked to start?
 
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Old 06-16-2018, 07:05 PM
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Oil reservoir is full bled all injector lines earlier today after changing fuel pump and was getting good pressure at that time. it is and was bellowing white smoke out of the pipes. replaced the return lines this afternoon late. Starter started getting hot before I could bleed all the injectors again, plus I ran out of starting fluid. Using that to get it running so I can bleed air at injectors. the one I tried to bleed this evening was blowing bubbles not spraying fuel like it was earlier. It was blowing white smoke but running ok before it went down.
 
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Old 06-16-2018, 08:10 PM
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Not knowing what you might have to work with, but can you manage to temporarily bypass the line from the tank and provide a direct line to the supply pump? If we are pretty sure it is pulling air in , you have to start somewhere and that way you would be eliminating the pick up tube and tank lines. Any kind of hose in a can of clean fuel would work since there is no pressure only suction up to the supply pump.
 
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Old 06-16-2018, 08:29 PM
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Thank you for that Idea had not thought to try that even though I had done that before on gas burners and seen it done a thousand times before. Will try that in the morning and update one way or the other. Shoot if it works I may just tie the jug to the mirror and limp it back home that way.....yeah I might be a bit red necked LOL!
 
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Old 06-16-2018, 09:10 PM
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IDI didn’t have a oil reservoir. But by ‘fuel pump’ are you meaning the lift/supply pump, or injection pump was replaced?
Fuel filter/separator was bled at its orifice?
Installing a clear tube inline on the supply pump inlet (from the tank ) would rule out air intrusion into the system, but if it pulls clean/clear from the tank, and the injector lines have inadequate fuel pulse, with a clear line installed on the return indicates bubbling,, most likely would be the injection pump.
Is it still OE injection pump? Usually not,, depending on your trucks miles..

Starting fluid is pretty harsh on the 7.3, careful with it..
 

Last edited by Hayapower; 06-16-2018 at 10:59 PM.
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Old 06-17-2018, 05:02 AM
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In addition, starting fluid when used in excess can take the top off pistons and do more damage than it is worth.
 
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Old 06-17-2018, 03:04 PM
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If an active glow system,, decent potential to ignite the saturated starting fluid and flame or blow out the intake. Seen ring lands blown completely out and all the piston debris in the pan. Crown damage etc.
In a pinch and with the glow system disabled for safety, old timers used a moderate gas soaked rag held ‘loosely’ into the intake stream while the engine is being cranked. It will run the engine off the gas vapor until the rag vapors depleat and is much less violent than ether. Best not to use any start assist on the 7.3,, shouldn’t need it,, but....
 
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