My '01 F-350 7.3 started stumbling around 2,000 rpm....would idle & run under that smoothly. I changed the fuel filter & now it will not run @ all. Any suggestions? Truck has 115,000 miles & has ran like a top until this
Crank position sensors are notorious for going bad on the 7.3’s. They’re like $25, don’t get the store brand, OEM only. Sent from my iPhone using Tapatalk
Any check engine light when it stumbled? Fuel pump Did it fill fuel bowl up after filter change? That’s how my 2000 model acted when fuel pump went out it had 200k miles tho
Yep. Check to see if filter bowl refills. I've heard of, but not personally seen heui engines running with a bad lift pump though poorly especially at high rpms. Until you crack the system open like changing a filter. Then it can't draw fuel anymore.
Check the maxi fuses under the hood,fuel bowl heater could have shorted out and blown a fuse.IT will not start if its blown.
Your computer has to see IIRC min of 9 volts to fire the engine while cranking if it goes below it wont start. If it starts with a jump then have your batteries checked.
No check engine light... New batteries, as of last night... Bowl does not seem to be filling... Tank is 1/3 full... I have not checked any fuses, yet... Thinking fuel pump as well. Thanks guys!!
Check for power and ground at the pump. If none, check fuses and inertia switch. If it has power and ground it's probably the pump.
Seems like you are onto something with the fuel bowl not filling. See that through as instructed above. If that doesn't get you back running, here's some extra info that may help future steps The ECM needs to see the following to instruct the IDM to fire the injectors 1. Batt positive voltage >10.5v With new batteries this should be a non issue 2. RPM > 150 As indicated above cam position sensors are known for going bad to the point some people carry a spare in the truck. This causes the truck to interpret inadequate RPM to start. The diagnosis is easy though, if the tach is moving when you are cranking its not likely a CPS issue. 2. Injection control pressure > 500psi This one is more difficult to observe but there are a few simple things to check. Unscrew the HPOP top plug and check to see it has oil in it (.75-1" from the top). If yes, unplug the injection pressure sensor and it will default to a control duty cycle that will allow the truck to start if the sensor is bad. After that the diagnosis requires more tools. You can of course observe whether the injectors are actually firing by checking for smoke when cranking. White smoke means they are firing...provided there is fuel in there to atomize. TL;DR - stick with the obvious lack of fuel supply to the bowl before caring about the information within.
Check the oil! I recently blew the oil cooler causing the motor to fill the cooling system with oil. It got hard to start, would just turn over and over. Popped the hood and no oil on dipstick but the overflow tank was running over black!
THIS^^^^ Best starting place. I had one go out cruising to the gulches replaced it with a parts house sensor and it went bad as well, but it did get me home. The OG did throw a code, but the parts house never did (it still ran but poorly) After that the next thing to check is the prefilters to the pick up inside of the fuel tank... Yes dropping the tank is a PITA but you can also modify the fuel filler overflow neck so you can actually fill up the tank without taking 15 mins to pump the last 3 gallons...
