Author Topic: firing on only "3" (Read 3382 times)

fritobandito · « **on:** January 13, 2006, 10:38:39 AM »

Hey guys, I have a situation. I took my headers off to clean them. I got impatient and decided to put them back on without getting new gaskets. I got it all buttoned up and fired it up only to discover that they were leaking. No big deal right. Just take them back off and get some new gaskets. Well, I let it run for a while only to see gas begin dripping from one cylinder out the exhaust port where it was leaking. Then, I watched as the other three pipes began their change to the gold color but the one didn't. I felt it and it wasn't getting hot like the others. Uh Oh, it's not firing. I haven't checked anything yet. I guess I'll start with the spark plug. Any ideas where else to look. Who knows how long this has been going on because I took it for a ride that way and it seemed to have the same get up and go as before. Wow, how fast would it be with that other cylinder pulling its weight?? Thanks for any help.

ray nielsen · « **Reply #1 on:** January 13, 2006, 01:21:53 PM »

The cylinders are "paired" on two ignition coils. One fires cylinder 1 & 4, the other 2 & 3. Coil or ignition module problems usually cause two cylinders to fail instead of the one you noticed.

Look at the spark plug for visual clues -- gas fouled with sooty deposits usually indicates carburetion problems. You might try tapping on each float bowl with a screwdriver handle to see if you can dislodge any crud blocking closure of a float needle against the seat.

Other than that you MAY need to delve into the carbs, not a job that's particularly easy, especially if you haven't done it before. Be sure to get a good manual before you start.

Red01 · « **Reply #2 on:** January 13, 2006, 09:20:46 PM »

With a cold cylinder, sounds like ignition. You can get a dead cylinder from a bad lead between the coil & plug. You can check this by swapping the leads in the coil pair. If the problem follows the swap, it's most likely the lead. (Could be an internal fault in the coil that is only letting spark out one lead, but that's pretty rare.)

jeepskate99 · « **Reply #3 on:** January 13, 2006, 09:40:47 PM »

Quote from: "fritobandito"

Hey guys, I have a situation. I took my headers off to clean them. I got impatient and decided to put them back on without getting new gaskets. I got it all buttoned up and fired it up only to discover that they were leaking. No big deal right. Just take them back off and get some new gaskets. Well, I let it run for a while only to see gas begin dripping from one cylinder out the exhaust port where it was leaking. Then, I watched as the other three pipes began their change to the gold color but the one didn't. I felt it and it wasn't getting hot like the others. Uh Oh, it's not firing. I haven't checked anything yet. I guess I'll start with the spark plug. Any ideas where else to look. Who knows how long this has been going on because I took it for a ride that way and it seemed to have the same get up and go as before. Wow, how fast would it be with that other cylinder pulling its weight?? Thanks for any help.

You too!! Mine was just a fouled plug from revving while cold. I do love the sound of that Yosh though. Thanks again for the fast shipping BTW.

Daytona · « **Reply #4 on:** January 14, 2006, 01:12:34 AM »

Hey frito! If you were down one cyl it wouldn't run worth a darn on a ride around the block! After revving eng to say 3k does the pipe heat up like the others? If so (i know here he goes again) a carb sync is needed. Your butterfly is closed off on that carb or carbs and only sucking gas no air! They will idle ok on 2 or 3 but as soon as you open it up it gets air and all 4 are lickin. You have a 97 rite? The older ones i find run better on a bit hotter plug, no need to use the enrichner (choke) unless it real cold. and no fouling of plugs like the stock NGK's.

ray nielsen · « **Reply #5 on:** January 14, 2006, 07:06:17 PM »

Due to the "pairing" of cylinders from one coil, an open plug wire WILL cause a misfire on TWO cylinders as the path for both sparks in interrupted. The plugs are essentially in series with each other, the spark traveling from one coil terminal to the spark plug, then from center to side electrode -- across the cylinder head, from side electrode to center electrode and back to the other side of the coil.

On one spark plug the spark jumps from center to side electrode while at the other it's reversed. Not the best idea in the world as the spark plug is designed to have the spark move from center to side electrode.

You can observe this by inspecting the plugs from two "paired" cylinders. One will show a clean portion of the center electrode where the spark originates, the other will show that same clean area on the side electrode where its spark starts.

fritobandito · « **Reply #6 on:** January 20, 2006, 07:16:32 PM »

thanks to all for the ideas. I haven't done anything yet as I've been out of town and then under the weather. Yeah, I thought it was strange that it would run good around the block. Still, the one pipe hasn't turned gold which leads me to believe it never was firing. Of course, I guess the air flow across it while riding may have kept it cool enough to prevent the color change. Does that sound wrong? Just theorizing. Could the exhaust leak be causing it to not have enough compression?? Anyway, gotta get on it.

Red01 · « **Reply #7 on:** January 20, 2006, 07:22:07 PM »

An exhaust leak won't directly cause a loss of compression, but it could lead to it happening. If the exhaust leak is close to the valve (like the header flange area), the cold air that can get in can lead to a damaged valve - and that will compromise compression.

fritobandito · « **Reply #8 on:** February 02, 2006, 02:51:24 PM »

Well, I finally got it back together last night with new exhaust gaskets. So, I fire it up and it's sitting there idling with the choke on high, and idling rather poorly. I'm feeling the pipes and cylinder one is still not getting warm, but not exhaust leaks thank goodness. I reach up and turn down the choke to about half-way, and all of a sudden the idle jumps way up. After a few seconds I feel pipe #1 again and it's getting warm. So, I take it out for a ride and it's doing great. I get back and all pipes are hot. No, I didn't touch them. Been there done that. Ouch!! So, it seems to be firng on all four again, even at idle. I don't know what happened. I'll be doing a carb sync. soon as well as adjusting the valve clearances. I believe I need new valve seals too. Don't know when that'll happen. Anyway, just thought I'd share.