Engine sputtering acts like it is not getting fuel

1996 FORD F-150
185,000 MILES • 5.8L • V8 • 4WD • AUTOMATIC
Avatar
SARAH MILES
  • MEMBER
  • 4 POSTS
It's spitting and acting like it's choking when you give it gas. We had it hooked up to AutoZone's machine before plugs wires and cap and code said random misfire. However, I unplugged Mass air plug and then replaced it and the hesitation stopped for a 15-mile ride. please help
Jul 9, 2022 at 9:26 AM
Advertisement
Avatar
AL514
  • Experienced Mechanic
  • 5,642 POSTS
Hello, are you saying that the truck runs better with the Mass Air Flow sensor unplugged? But the problem returns when you plug it back in? If it's running better with the sensor unplugged, the engine computer will run a default fuel strategy because it can't get any reading from the Mass Air Flow sensor, so there could be a wiring issue to the sensor causing the sensor to give incorrect readings. Are there any new codes besides the random misfire code?

https://www.2carpros.com/articles/how-a-mass-air-flow-sensor-works-maf
Jul 9, 2022 at 10:54 AM
Avatar
SARAH MILES
  • MEMBER
  • 4 POSTS
Not exactly. My husband attempted to unplug it, but it ran worse. And would not crank back. So, we replaced the distributor cap, and it did okay for a few days.
Jul 9, 2022 at 11:00 AM
Avatar
SARAH MILES
  • MEMBER
  • 4 POSTS
No.
Jul 9, 2022 at 11:05 AM
Avatar
AL514
  • Experienced Mechanic
  • 5,642 POSTS
What is it doing now? You say it was okay, but do you feel it is running at full power? It's a 5.8-liter engine, it should have a lot of power. So, times what happens is the performance declines over time and you don't really notice it so much. And if I, for example, were to jump in and take a ride I would probably notice a lack of power right away. How does the truck idle when its sitting in Park?
It sounds like it probably needs a full tune up, spark plugs, wires, fuel filter, air filter. If a new Distributor cap helped somewhat, then the rest of the ignition system really should be done. You probably want to add a fuel system cleaner with a full tank of gas as well. It's an older truck with a lot of miles, the fuel injectors are due for a cleaning too, so a fuel system additive will help with that.
Jul 9, 2022 at 11:07 AM
Avatar
SARAH MILES
  • MEMBER
  • 4 POSTS
The idle is okay. It's taking off okay, then it spits sputters give it a good bit of pedal and it acts like it wants to jump and spit even kind of jerks Lol. My husband filled it up with non-ethanol gas thinking it would clean it out.
Jul 9, 2022 at 11:12 AM
Avatar
AL514
  • Experienced Mechanic
  • 5,642 POSTS
You should have him pull the spark plugs out and see what condition they are in, if the truck hasn't had a tune up in a while there can be any number of components that are just plain worn out. Checking the spark plugs is a good place to start, it sounds like there are multiple cylinders misfiring and if it's running that bad, it's possible that the Catalytic Converter will be damaged by the misfiring cylinders. When a misfire happens there is unburned fuel and air exiting the cylinder into the exhaust, that unburned fuel can cause the Catalytic Converter to overheat and melt the down, causing it to clog up the exhaust, at that point you can put the pedal to the floor and the truck will barely get out of its own way. With serious hesitation and extreme lack of power.

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

https://www.2carpros.com/articles/how-to-tune-up-a-car-engine
Jul 9, 2022 at 11:28 AM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.