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1994 7.3 "starving" issue

1K views 9 replies 5 participants last post by  themule67 
#1 ·
Hello everyone I've been having some issues lately with my 1994 7.3.

First off I'm no diesel expert so anything you can offer would be very much appreciated. So where do we start..
Lately my truck has been having issues keeping running in the morning. It will start just fine and ill let it start to warm up. After 20 seconds or so idling it starts struggling to idle or even raise the rpm's. Constantly dies and barely will run. It sputters and dies sputters and dies. Also I have a 6 position chip . On stock mode once the problem starts the throttle won't budge "normally". So ill switch it through the hp settings and will ask more lively on any position other that stock. After starting it over and over for 10 to 15 minutes trying to clear it out it will run fine all day. I've unhooked the ICP to see it that's the problem its not. Replaced the fuel filter few months ago.

Truck was sitting for 5 years tell I could get it fixed but was running fine for 6 months tell now. Could it be as simple as the oil is contaminated from sitting for so long? Oil was changed when the mechanic fixed it.

Thank you
 
#2 ·
Hi! Danepope7.3 The first thing that you want to start with is physically removing your chip they can and will fail. Sometimes it can be by a loose connection at the ECM or it could have just failed. The last time my Bully dog 6 position failed mine just would not start even if I turned it back to stock once I unplugged it from the ECM she fired up and ran great like nothing happened. Start with cheapest first it doesn't cost anything to try just a little bit of your time it's also, IMO best if you keep it removed until you figure out what is wrong. Not sure on the oil contamination causing it but, have you checked your oil level on the dipstick and also, oil level in the HPOP it should be within an inch of the top. Have you checked your fuel filter or changed it out could possibly be plugged also, check the valve cover connections disconnect one and see if the plug has any oil in it if so, time to replace them but, temporarily you could spray electrical cleaner into the plug let it dry out for few minutes and then plug them back in. Also, disconnect your IPR plug check for oil in the plug if so, time to replace. If you have a spare CPS which you should always keep one in the glove box try changing it out they are fairly inexpensive. Good Luck! keep us updated.
 
#6 ·
Thank you for your response. I'm trying to grasp at why my chip failing would be my problem. I totally comprehend how these motors work but how everything ties in and one effects another its out of my league. Why or how could it be a chip issue when it runs right off the bat and then acts like its staving for fuel



Thank you for your response. I'm trying to grasp at why my chip failing would be my problem. I totally comprehend how these motors work but how everything ties in and one effects another its out of my league. Why or how could it be a chip issue when it runs right off the bat and then acts like its staving for fuel after 20 -30 seconds after firing up. Totally agree with Sohrab Tabrizi on this one. It was one of my first guess for the situation. But me not knowing that much didn't know they gave a do called "check valve " But like I said any input is helpful. Did some maintenance today and going to see how it runs tomorrow. Much love yall 🤟
 
#3 ·
It could also, be a weak and or failing lift pump behind the fuel bowl you could use a regular tire gauge on the schrader valve on the side of your fuel bowl make sure you use a rag or you might get sprayed. I believe that you want to see about 40-50 psi you could search for that info. to verify up at the top of the page. Being that it has sat for so, long could it be possible for algae to have grown inside your fuel tanks not sure just a thought.
That's why I said to check your fuel filter they do make an additive to kill the algae if that is the case.
 
#8 ·
It could also, be a weak and or failing lift pump behind the fuel bowl you could use a regular tire gauge on the schrader valve on the side of your fuel bowl make sure you use a rag or you might get sprayed. I believe that you want to see about 40-50 psi you could search for that info. to verify up at the top of the page. Being that it has sat for so, long could it be possible for algae to have grown inside your fuel tanks not sure just a thought.
That's why I said to check your fuel filter they do make an additive to kill the algae if that is the case.
Thank you sir for your input. I did alot of maintenance today and will check fuel pressure tomorrow.
 
#4 ·
you have an air intrusion in your fuel line or a check valve is failing somewhere. whats happening is over night the fuel is draining back to your tank. when you first start in the morning you use the fuel in the filter bowl and when that runs out you have to wait for it to fill back up and purge lines before it runs for the rest of the day. if you park on a downward slope. nose down. it should do this less or not at all. I have an pre stroke but seems like the same issues I have. check return lines if they have a one way valve back to the fuel bowl like mine did.
P.S. the only contaminate that will stop that truck like that are ball bearings.
 
#7 ·
you have an air intrusion in your fuel line or a check valve is failing somewhere. whats happening is over night the fuel is draining back to your tank. when you first start in the morning you use the fuel in the filter bowl and when that runs out you have to wait for it to fill back up and purge lines before it runs for the rest of the day. if you park on a downward slope. nose down. it should do this less or not at all. I have an pre stroke but seems like the same issues I have. check return lines if they have a one way valve back to the fuel bowl like mine did.
P.S. the only contaminate that will stop that truck like that are ball bearings.
Totally agree with you that was my first thought but it was hard to find info on it with out some serious digging. Did some maintenance today hoping it will help if not next step would be the valve. You happen to have any links for this valve or others that can be causing this? Thank you sir 🙏
 
#5 ·
I agree with what mule said. I would check fuel pressure first off. Then loose the chip and work into it. Others will agree too.
 
#9 · (Edited)
Even without any check valve, fuel can only drain back if there's an air leak. But the check valves are all in the engine valley; the first 2 are in the diaphragm stage of the fuel pump; 2 more in the piston stage; and 1 at the strainer outlet to the tank return beside the .020 orifice.

 
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