Engine running rough following spark plug wire replacement..

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May 27, 2012
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21
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Location
Boise, ID
So I just replaced the spark plug wires on my 77 FJ40's 2F motor, in addition to the rotor and cap. I haven't replaced the plugs because I didn't have the right spark plug socket.

Following this, the motor is running rough. It doesn't want to start up regardless of the choke position. It does start, but it takes several long attempts, and needs to be in just the right choke position. Also, the engine sputters quite a bit when low in a gear, and it backfires.

This FJ40 is new to me as I just bought it. But there is a clear difference in how it's running now, and changing the wires and rotor is the only thing that's been done since it ran well yesterday.

One more thing- I smell pretty strong fumes. I don't know if it's fuel, or if it's the rusted out muffler throwing exhaust at me (top's off). The muffler needs replaced, it's rusted wide open. Would this actually cause the engine to run poorly? If so I don't understand the recent onset of problems overnight.

Thanks!
 
When you did the wires, did you pull them all off or did one at a time?
 
Are you sure you got all your wires tight on the connections? Could be your boot is down, but your wire isn't connected at the plug, or in the cap.
 
Yeah, sounds to me your wires got crossed and now your firing order is poop.
 
Thanks for the replies. I will answer the questions asked all at once here..

I understand the importance of replacing each wire one at a time. That said I replaced them all at the same time because: I first confirmed that the numbering on the old cap was wired correctly to each cylinder. I then confirmed that the NEW cap had an identical numbering layout as the old cap. Knowing these 2 things, I felt good about pulling them all off and replacing them in order. The numbers went 1-6 starting with wire 1 going to plug 1 on the end closest to the front of the vehicle.

I double checked the order and that I heard and felt a "pop" each time I pushed a boot on.

Even though I was very cautious, it's still possible something's not on solid. I didn't love the way the plug wires connected to the cap. There just isn't the same "pop" on that end. Tomorrow I will replace the plugs themselves and double check the order. I will plan on sliding the boot back to expose the connector and then pushing the connectors on the plugs to get visual confirmation.

Is it advisable to check for spark on all the plugs while the plugs are out? I've never had a car with an engine so accessable and have only done this on my stand up jet ski's, so I should make sure I do it right. Actually, come to think of it, this would be pretty difficult by myself. I don't have a helper to turn the key while I look for spark..
 
Check the timing, your dist could have moved while messing with it. Make sure the cap is properly seated all the way down, some do not fit like the old ones.
 
Be sure to pull the boots back at the cap and reinstall them, making sure the wires fully seat, then slide the boots down. Do both ends of the coil wire also.
 
Were the new wires cut to fit? Even if tailor made it doesn't mean new stuff is always perfect. Check continuity on every wire. Is the cap completely and squarely seated?
 
Firing order:

15 too young
36 too old
24 just right

1-5-3-6-2-4
 
Check the timing, your dist could have moved while messing with it.
Oh man. Yeah I think I could have messed up the timing. Here's where my lack of experience shows.. When I bought the FJ40, the PO gave me a set of new wires, plugs, cap, rotor, and contact set. I figured "what the heck, I'll just swap throw these in real quick. I identified the old parts and replaced them with the new. I would bet that my problem is not with the wires but with the fact that I replaced the distributor rotor (part 12-0122) and contact set (part 370123). When replacing, the new parts probably didn't go in with the same exact tolerances as they were originally.

Does this sound like a possibility??

This is a little bit nerve racking, considering I just read a bit about adjusting the distributor timing on an FJ40 and I am.. well, a bit overwhelmed with the can of worms I may have opened up. I guess the good thing is that it RUNS. It just seems as though learning to set the timing is a skill learned over time and observation..
 
Points?

Time to check the point gap.
 
wont have the issue of getting them on wrong if you use a OEM Toy cap and wires.......they are both marked with #'s(and the wires are even dated)

makes life much easier and they dont cost anymore than other brands and are better
 
Seems that it WAS timing. Apparently I moved the distributor when I swapped the rotor and contact set. I went to drive it yesterday AFTER my last post on this thread and it was hardly driveable. I had to pull over and work on it and it wouldn't start no matter what position I put the distributor in. Luckily I got it fired up eventually. Went and grabbed a point gap feeler and set the gap to 0.018" at the high point of the cam in the distrbutor. It runs better, but still probably at 80% of how it ran when I drove it home. So I think I will need to take it in to have the timing done. I don't have a timing light.


wont have the issue of getting them on wrong if you use a OEM Toy cap and wires.......they are both marked with #'s(and the wires are even dated)

makes life much easier and they dont cost anymore than other brands and are better
Yeah that's what I used. Which is why I was able to do all the plug wires at once..
 
Sounds like you're on the right track.
 
Seems that it WAS timing. Apparently I moved the distributor when I swapped the rotor and contact set. I went to drive it yesterday AFTER my last post on this thread and it was hardly driveable. I had to pull over and work on it and it wouldn't start no matter what position I put the distributor in. Luckily I got it fired up eventually. Went and grabbed a point gap feeler and set the gap to 0.018" at the high point of the cam in the distrbutor. It runs better, but still probably at 80% of how it ran when I drove it home. So I think I will need to take it in to have the timing done. I don't have a timing light.



Yeah that's what I used. Which is why I was able to do all the plug wires at once..

psh you don't need a timing light - if it is running right now you are close.. just rotate it slightly until you get a nice idle at the right rpm.. check the throttle response and call it good. not sure if this is bad technique but it's worked for me... :whoops:
 

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