Engine still runs like ass.

chaka

Founding Member
Mar 1, 2002
1,342
0
0
Boston, MA
This is a stock 86 302 in a F-150 4x4

So far I have changed the TFI, coil, plugs, wires, cap, and rotor. Timing is set properly. Compression check done. 150-145 across the board. #1 a little low at 140.

In park and neutral the engine will run decently with a little shake. and rev up easiely. Went put into gear the engine shakes and there is a major power loss takes awhile to accelerate.

I am stumped. What could be causing this?
 
  • Sponsors (?)


A fuel problem (plugged filter)? Those compression numbers look good, and the outlyer isn't too far off. Could also be a weak spark; do you get a nice fat blue spark or a yellow/orange one?
 
A nice fat blue one.
Coil is getting 13.5 volts too.

Not sure on the fuel, but I know the exhaust smelled rich to me. What kind of tests can I run to determine fuel problems??

Could it be the Pickup in the dist??
 
I've heard that the pickup in the dizzy will cause tip in stumble; definitely a possibility though. Fuel problems are pretty tough to track down unless you aren't getting fuel at all. Usually if a fuel filter is plugged, it will run fine (even when idling in gear), but will lose power when you try to accelerate. Certainly worth replacing the fuel filter anyway.
 
Will check those things too. Thanks :nice:

I removed the pulley off the smog pump when I first bought the truck because it was seized up. For some reason it unstuck itself. Could this be causing a problem?
Already checked for vacuum leaks. But won't hurt to do it again.

Checked the vacuum at idle and it is around 20psi. Sound about right?
 
20 inches of HG sounds about right; however you should be more concerned with how fast your vaccum gauage returns to 20" when you rev the engine and let off the throttle. If you have no vaccum leaks the needle should drop when you open the throttle, but quickly snap back up when you let off. If the needled slowly returns...you have a leak somewhere.

You said your #1 is low on compression, does your vaccum guage needle bounce back and forth when your engine is idling? If this is the case, you have a valve that isn't seating correctly; which would also give you low compression. (although 140psi is still decent, i doubt it is due to a cracked valve)

As others mentioned, a plugged fuel filter can cause all sorts of problems; you should probably see what kind of fuel pressure you're getting on the fuel rail.

hope this helps
 
jerry beach said:
I say pull the codes as jrichker so kindly provided you links for. Its really easy, and cheaper than throwing parts at it. Wont cost you anything to find out.

Plan on this weekend. No time till then.

Needle bounces back quick and it is a steady reading at idle.