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| 7.3L IDI (Non-Powerstroke) Diesels Technical discussion of topics related to vehicles powered by the 7.3 Liter In-Direct Injection Navistar engines. |
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Hard start/start then die Help!
I have an '89 F-250 with a 7.3L. It has new glow plugs and batteries and the fuel filter should be fine, It has 260,000 miles, and generally runs great once started. On a cold start during the first crank the truck often starts right away then dies. After this it requires about 30 seconds of cranking to start. Pushing the gas pedal helps it start quicker. It start just like this cold even with a full tank of fuel. The starting problem seems to be worse when there is less than a quarter of a tank of fuel. The truck also runs funny and kind of surges in power and has died at stoplights and such when it has under a quarter of a tank. I never have issues when warm and running other than with less than a quarter tank. It sometimes also has a tough time starting hot when under a quarter tank also. I have transparent fuel return lines and can see that after the initial cranking when it fires up for a second the lines are empty. Im not sure whats going on, maybe a bad mechanical fuel pump?
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It could be the fuel pump and it could be the cold start solenoid on the injector pump. You may have a bad sender in the tank making you think you have 1/4 tank and it is actually almost empty, or you may have to remove an clean the pick up. Check the fuel pressure when it is running good and when it is acting up. It should be between 3 and 5 psi.
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I was just read a post by "powerstrokes only" describing an old injector pump losing its prime overnight. Could this be what I am experiencing also rather than the cold start solenoid or mechanical fuel pump? I think this might be it because the motor does fire up quickly at first possibly burning the fuel that was still in the injectors, then needs to be cranked for a bit til it gets enough fuel to run. I dont know... I still think it might just be the mechanical pump though. I dont have a fuel pressure gauge either maybe its time to invest.
Any more opinions would be appreciated. especially from "powerstrokes only" |
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cold start, rough idle at ¼ tank
Have the same trouble when under ¼ tank, thinking bad fuel gauge sender? so I never let the tank get below ½. no problems since!
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Check your return fuel lines between the injectors. If they even have the smallest leak, overnight it will syphon all of the fuel out of the lines back to tank. Then when you start it you basically have to reprime it.
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losing its prime
My 87 is exhibiting similar symptoms. I plan to place a check valve in the fuel line and see if this helps. will get back, Jim
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Yeah im kinda thinking that the fuel pickup thing and the starting thing are 2 separate issues that can occur at the same time. I never even thought of adding something simple like a check valve...Uh duh I'll try it too, thanks for the good idea, I'll post my results also.
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There is a fuel strainer on the pick up tube in the tank and there is a check valve around 1/4 the way up the pick up tube. The purpose of this check valve is to open if the strainer on the bottom of the pick up tube would become blocked from your fuel jelling or algie growth. You may want to drop the tank and see if it is blocked or dirty because if it is the engine will start to suck air around 1/4 tank.
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