Need Help with 1985 f150

Reply Subscribe

Thread Tools

Search this Thread

May 7, 2008 | 11:00 PM

1968mustang302

Thread Starter

New User

Joined: May 2008

Posts: 15

Likes: 0

Need Help with 1985 f150

i recently just got a 1985 f150, it has a fuel injected 302. However it is not running right, it will start up and idle kind of fine (around 1100rpm) but is not very responsive at all off idle and will intermittently backfire and misfire through the intake.. i have talked to several mechanics and they all told me it was due to bad fuel as the truck was sitting for about 5 years.. but we drained the fuel added new gas and it does the exact same thing... me and my dad can not figure it out.. so any help would be great..

May 7, 2008 | 11:49 PM

xlman

Senior User

Joined: Apr 2006

Posts: 146

Likes: 1

From: St Lawrence Valley - NY

How many miles on it? Sounds like a timing chain problem or valve trouble.

May 8, 2008 | 12:37 AM

1968mustang302

Thread Starter

New User

Joined: May 2008

Posts: 15

Likes: 0

it has 60,000 original miles and 20,000 miles on a rebuilt motor.. im pretty sure it has something to do with somekind of sensor...map, tps etc

May 8, 2008 | 05:58 AM

ri_truck_guy

Posting Guru

Joined: Jun 2002

Posts: 2,091

Likes: 3

From: Suffolk, VA USA

When you drained and changed the gas did you change the fuel filter? And did you use a good fuel treatment like the Lucas product? Get an OBD 1 code reader and see what the computer may be storing. Also, if you haven't driven it for any distance, check your alternator belt tension, battery connections, and that your voltage regulator is putting out enough power. The truck will run exactly as you described if the battery has just enough power to start, but the system isn't charging.

May 12, 2008 | 08:57 PM

Big_kid

Junior User

Joined: Jun 2007

Posts: 62

Likes: 0

From: Virginia Beach

I had similar trouble after swapping a '90 engine into my '85. It all went away after I unplugged the knock sensor. It's in the lower intake, driver's side, right about the middle. It resembles an AC Pressure switch, kinda.

Also- have you replaced the plugs? I had a new set in the engine I took out, they fouled after ZERO miles. All the farting around in the driveway did them in.

May 12, 2008 | 10:40 PM

Americanmadeford

Senior User

Joined: Jan 2007

Posts: 292

Likes: 0

From: SE Alabama

5 Years? Tank is probably rusted to hell. Take the fuel filter out and see what's in it. If there's rust-dust youll need to drop the tank and clean it out.