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  • 1965 - 1973 Classic Mustangs -General/Talk-
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Why is my engine running rough?

  • Thread starter Thread starter shatter
  • Start date Start date Jul 7, 2007

shatter

Member
Oct 13, 2005
54
0
6
Northern California
Jul 7, 2007
#1
  • Jul 7, 2007
  • #1
After some prodding from others, I decided to take my 69 Coupe out of storage. It has been sitting for 10 months plus or minus. When I put it in storage, I filled the tank w/ 91 octane fuel and added fuel stabilizer. Now that I took it out it idles rough and doesn't have much power when you step on the gas. It has the original 302 w/ 2-barrel autolite carb. I am running the stock 351W cam with a MSD 6A ignition and blaster coil. Here are the things I have done so far without fixing the problem:

Rebuilt carburetor
Drained fuel out of tank and replaced with fresh 91 octane
Checked compression of cylinders (all were 150-160 except one which was around 135-145)
Checked resistance of plug wires (all were close to the same resistance)
Checked for vacuum leaks (going to replace vacuum hoses I think just to be extra sure)
Changed out spark plugs/checked gap
Checked timing

I am running out of ideas. Was thinking of getting a rebuilt carburetor and putting that on. When adjusting the mixture screws on the carb, they don't seem very sensitive (currently set around 3.25 turns). This made me think that maybe my carb is just messed up somehow even after the rebuild kit.

Any ideas?

Update: Will be replacing the vacuum lines and found a friend with a vacuum gage so I can check that soon. Also, realized I had not replaced the gasket between the PCV spacer and the intake. Will also double check intake manifold bolts.
 

red65

Member
Apr 12, 2003
411
0
17
Ann Arbor, MI
Jul 8, 2007
#2
  • Jul 8, 2007
  • #2
shatter said:
Any ideas?
Click to expand...

It's common for corrosion inside the fuel lines (and tank) to plug or partially plug the fuel pickup, filter and lines, especially after sitting for a while. Disconnect the fuel line from the fuel pump, tank and carb, clear both lines out with compressed air (contain the splashing fuel, of course - be careful), replace the fuel filter, and see if that helps.
 

zookeeper

Founding Member
Aug 25, 2001
3,415
63
109
Rogue River, Oregon
Jul 8, 2007
#3
  • Jul 8, 2007
  • #3
10 months really isn't all that long if the car sat in a garage. My wife;s '69 Corvette usually sits that long and sometimes we have problems and sometimes we don't, but it's always the accel pump in the carb. I drained the old gas from my '68 last year when I fired the new motor for the first time, but the old gas smelled fine and worked well in the lawnmower, and that car had sat since '02. I'd have another look at the carb if it were me.
 

shatter

Member
Oct 13, 2005
54
0
6
Northern California
Jul 8, 2007
#4
  • Jul 8, 2007
  • #4
Problem solved! -Thanks for the posts.
 

zookeeper

Founding Member
Aug 25, 2001
3,415
63
109
Rogue River, Oregon
Jul 8, 2007
#5
  • Jul 8, 2007
  • #5
What did you find?
 

shatter

Member
Oct 13, 2005
54
0
6
Northern California
Jul 11, 2007
#6
  • Jul 11, 2007
  • #6
I found out that I am an idiot who crossed the #3 and #4 plug wires somehow. I thought I was being so careful not to cross the wires when I was messing with the plugs when I put the car into and out of storage that I didn't go back and verify until there was basically nothing left to heck.
 
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