Fuel or ign??
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Joined: Jul 2007
Posts: 54
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From: Elizabethtown IN
Fuel or ign??
I am working on my son's 86 and so far can't find what's wrong. It starts fine, idles fairly well, and will accelerate slowly to WOT. Problem is that it won't accel quickly, just stumbles. I've installed new plugs, verified that the all inj check close to 16 ohm and timing has been set. I replaced a bad ign mod, runs better but still stumbles. I pulled the injector plugs while idleing but didn't notice a change. I've no experience w/ this, not sure what controls the fuel delivery. There are no codes since I replaced the inj mod. Can low voltage cause this? Am getting 14.3 v when running but the batt does go dead quickly.
I would appreciate some feedback on where to look. I plan on checking the coil tonight.
I would appreciate some feedback on where to look. I plan on checking the coil tonight.
Team Owner
Joined: Sep 2001
Posts: 62,158
Likes: 1,732
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Check fuel pressure, at idle and WOT.
Verify that spark is getting to each cylinder.
May want to double check MAF connections.
My money is on an electrical/wiring issue. My 86 is having them left and right.
Verify that spark is getting to each cylinder.
May want to double check MAF connections.
My money is on an electrical/wiring issue. My 86 is having them left and right.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
I was having the almost exact problem with my 86 awhile back. It would start up fine, idle a little shakey, and drive like crap with slow accleleration. I checked everthing I could think of with no codes. I could set the timing with a timing light, ect.
Finally one day, I decided to check the position of the distrubitor. Found out that it was installed incorrectly by my father who told me it was right. If you can't believe your own father...who can you believe?
Anyhow, I got #1 piston to TDC, pulled the dist and realigned, and rerouted the spark plug wires. Started it up and ran like a new car. Before this, it would not even turn the tires over. Now I can do a burnout easily.
Get the #1 piston TDC and remove the dist cap and see if the tip of the rotor is pointing towards #1 cylinder or at the left rear tip of the plenum. It should take about 10-15 minutes to check this.
Finally one day, I decided to check the position of the distrubitor. Found out that it was installed incorrectly by my father who told me it was right. If you can't believe your own father...who can you believe?
Anyhow, I got #1 piston to TDC, pulled the dist and realigned, and rerouted the spark plug wires. Started it up and ran like a new car. Before this, it would not even turn the tires over. Now I can do a burnout easily.
Get the #1 piston TDC and remove the dist cap and see if the tip of the rotor is pointing towards #1 cylinder or at the left rear tip of the plenum. It should take about 10-15 minutes to check this.
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Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
This one. It will thrown a code 42 naturally. Unplug battery for 10 min to clear.
Also, run the car with this plug disconnected to rule out a slipped timing mark. If it improves, you're probably setting the timing to a false timing line that has slipped.
Also, run the car with this plug disconnected to rule out a slipped timing mark. If it improves, you're probably setting the timing to a false timing line that has slipped.
Team Owner
Joined: Jan 2003
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From: Summerland B.C. Canada