Weak Spark / Hard Start
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Tuned
Joined: Jan 2006
Posts: 362
Likes: 78
Weak Spark / Hard Start
I have an intermittant hard start condition with my 1989 F-150. (302, 5 Speed, 137,000 miles.)
In testing for a spark at the plugs, I get a very weak yellow spark jumping an .045 Spark Plug gap. (Had hoped for a nice fat blue/white spark.)
New plugs, plug wires, dist cap, and rotor. Rebuilt dist and TFI unit( from Napa) and a new coil. No avail. Have also cleaned all grounds.
Will often start up just fine. When it acts up it will just barely fire and then die out. Can smell fuel. Really hard to get it started after that.
Thinking it is this weak spark deal, everything in the fuel system is new.
Special thanks to the many good responses in this forum. This is my first post. Up to now I have always been able to find my answer by searching other's problems.
In testing for a spark at the plugs, I get a very weak yellow spark jumping an .045 Spark Plug gap. (Had hoped for a nice fat blue/white spark.)
New plugs, plug wires, dist cap, and rotor. Rebuilt dist and TFI unit( from Napa) and a new coil. No avail. Have also cleaned all grounds.
Will often start up just fine. When it acts up it will just barely fire and then die out. Can smell fuel. Really hard to get it started after that.
Thinking it is this weak spark deal, everything in the fuel system is new.
Special thanks to the many good responses in this forum. This is my first post. Up to now I have always been able to find my answer by searching other's problems.
Posting Guru
Joined: Jun 2004
Posts: 1,781
Likes: 1
From: Central NY
Not sure.... but a weak 12v to the coil would cause a weak spark. I would start by checking the voltage into the coil and looking for corrosion. Then checking the contiditon of the batt, batt cable, solenoind, and Alternator. Lastly clean up you connections (+/-) at the battery. (+) at the solenoid, (-) at the block, frame, and body.
ps - these trucks are commonly found to have corrosion inside the battery cables. Maybe you should start there.
ps - these trucks are commonly found to have corrosion inside the battery cables. Maybe you should start there.
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Hellbore
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Jun 11, 2006 01:40 AM
