91 F-150 302 - Engine Troubleshooting


	Auto Repair Home	SEARCH POSTS	WHO'S ONLINE	LOG IN

Automotive Repair

Car Troubleshooting Topics
  Car Troubleshooting
  Engine Troubleshooting
  Engine Fault Codes
  Electrical and Wiring
  Transmission Problems

Car Repair Topics
  Car Making Noises
  Car Stereo Repair
  Heating or AC Issues
  Motorcycles and ATVs
  Tricks of the Trade
  Truck Repair Advice

Site Options:
  Login
  Sign up here!

Latest Forum Post

Lukewarm Heat............

New antifreeze reverse flush heater core...

multiple warning lights

2013 GMC Terrain 130,000 miles 4 cylinde...

2014 Nissan Sentra Shaking

Car recently started shaking when accele...

Buy Flualprazolam Powder Online Whatsapp: +1(424) 328-1086

N/A

1989 toyota pickup 3.0 crank no start

I have a 1989 toyota pickup 3.0 crank no...

Strut spring orientation and strut mount tension nut

2017 Nissan rogue awd 2.5 L Put in Monro...

Transmission stuck in part, I have tried everything

So I'm working on my elderly fathers 201...

2017 dodge journey LED headlights on/off randomly

Year of vehicle 2017 Make of vehicle dod...

Kia Soul starter replacement issues!

Okay so my car is a 2010 Kia soul 2.0 en...

Please Help - Knock sound & engine fail

Hi all, Hoping to get some insight and ...

91 F-150 302

Sign up here!

Search for (search options)

Auto Repair Home>> Automotive Repair>> Engine Troubleshooting

sparticas44
New User

Jul 31, 2011, 12:36 PM

Post #1 of 4 (1918 views)

91 F-150 302	Sign In

Ok so my truck isn't running right and I am kinda flustered now about what it could be. My truck has a pretty bad miss in it and I can't find out whats doin it. I have changed the following: Spark Plugs, Wires, Coil, Distributer Cap, Rotor Button, and 4 of the injectors. I have run a compression test on the engine on all cylinders and they all have good compression. Now I was noticing that the truck ran rich on gasoline. So I know it's got good fuel pressure. I also noticed something odd. You can cap your hands over the throttle body where the main air duct should go. Now I was told that doing so should kill the engine due to no air getting into the engine. But this wasn't the case. It simply bogged down and ran a little smoother. I am thinking Vacuum leak. but i am not sure. Any thoughts?

Sidom
Veteran / Moderator
Sidom profile image

Jul 31, 2011, 1:40 PM

Post #2 of 4 (1903 views)

Re: 91 F-150 302	Sign In

Very possible.....

Those were good for vacuum leaks around the plenum.... Get a can of carb cleaner & spray around the intake. If it idles up or does anything then more than likely you have a vacuum leak....

sparticas44
New User

Jul 31, 2011, 1:51 PM

Post #3 of 4 (1896 views)

Re: 91 F-150 302	Sign In

Thanks. Will do that. I'll post an update if it doesn't yeild a result.

Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Jul 31, 2011, 8:31 PM

Post #4 of 4 (1885 views)

Re: 91 F-150 302	Sign In

Vacuum leak will also make the engine run rich because the fuel system is speed density based. Basically the fuel system relies on the MAP sensor to determine engine load. Vacuum leak will make the computer believe the engine is under load because it is seeing a high MAP sensor voltage and inject more fuel.

Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

Search for (options) Privacy Sitemap