XJ550 Won't start. It was fine last week.

Hey folks I have a 1982 xj550 maxim. Someone gave it to and I fixed and It was running good, I tried to started today but it won't fire up. After a while trying to fire it up I had like a big explosion ( really loud) then my battery died, so I charged the battery and tried again and had another big explosion. So I thought maybe a have an electric problem, I was going to check the spark when I realized I have spark with the ignition off. So I don't really know what's wrong with that and don't know what to do.
If someone of you guys can help I'll be very grateful. ( English is not my first language so I'm trying my best)

 

how have you concluded that you have spark with ignition off,? do you mean the ignition is still "on" when key is turned "off", or something else?

 

If it ran well last week the issue should be minor. Perhaps the petcock was left on "prime" or the petcock is leaking and flooding the engine. Pull a plug or two and check.

 

Actually I remember I left the petcock on prime and was leaking a lot.

 

Remove the plugs, dry out the cylinders, replace the plugs, STOP THE LEAK and the bike will / should start. This is a fuel issue that is common with the XJ's. Check for fuel in the crankcase.

 

Thank you so much.

 

I pulled the spark and as soon as we touched the spark plug to the engine it sparked with the ignition off and on.

 

i would'nt worry about that, its probably just a charge left in the coils , after unplugging

 

Okay, thanks

 

So I'm back. I ended with dirty and plug carburators so I rebuild them. I put everything back Together and tried to start the bike but SURPRISE I don't have sparks. I checked the coils, ignition switch, I also updated my fuse block and checked the kick stand safety mechanism, I also have a good battery voltage. I don't know what else I can check. Please HELP.

 

did you turn the kill switch back to run?

check for voltage at tci on the red wire.
make sure battery is good and fully charged.
do a voltage drop test on battery hook meter to battery check voltage then press starter button see what the voltage drops to.
what is resting battery voltage and voltage drop?
a 550 will turn over well and still not start.

check your work on the fuse block replacment make sure you have voltage on both sides of the fuses

 

Yes, I did turn the kill switch back to run.

I also checked the voltage at tci on the red/ white wire. The battery voltage when resting is 12.5 and I will check the voltage drop. On the fuse block I checked the ignition wire but I'll check the rest of them.

 

what voltage did you get at tci?
could be the kill switch and related connectors are dirty and need to be cleaned.
test tci voltage with connector unplugged this may help see if you have voltage drop from fuse to tci. which would indicate dirty poor connections from fuse to run/kill switch and to tci. test points along the way.
at fuse
at connector to kill switch
at tci
and at ignition coils
all should be very close to battery voltage.

have you ohmed out the coils and pickup coils?

most important is check work you did from when it ran to now.
that is where any changes were made

 

I'm here again.
Voltage at tci is 11.79
Battery voltage 12.75
Battery voltage drop 11.45

I tested :
At fuse
At connector to kill switch
At connector to ignition switch
At tci
And Ignition coil also pickup coils.

All good and close to Battery voltage. I checked the fuse block all good.

So the newest thing that I found was:

1- Coil wire #2 is spark weak or decent spark.

2- Coil wire #3 spark decent.

3- Coil wires #1, #4 intermittent spark and after cracking when turn ignition switch off i
I can see a little spark.

So right now I don't what's really wrong. Coil?

 

unscrew the plug caps and trim back the spark plug wire 1/4 inch . the plug wires can corrode.
measure resistance of plug caps and plug wire end to end on each coil

Pick-up coils:
650 ohms +/- 20% = 520 ohms to 780 ohms acceptable range
Ignition Coils:
Primary side (input from main wiring harness):
2.5 ohms +/- 10% = 2.25 ohms - 2.75 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
11K ohms +/- 20% = 8,800 ohms - 13,200 ohms acceptable range


Spark plug caps:
10K +/- 20% = 8,000 to 12,000 ohms per cap acceptable range

Spark plugs:
0 ohms per plug

how old are the spark plugs

 

I don't know exactly how old are the spark plugs but I'm testing with a new spark plug

 

I checked and I don't have any resistant on the spark plug caps. So that mean they are bad?

And I tested the ignition coils again both of them are resting good on the primary side but the one that's connected to cylinder 1&4 is showing nothing on the secondary side. That means that one is bad?

 

they read 0 ohms on caps? are the original equipment or replacments?
you should also test the other caps.
xj4ever sells replacments both oem and aftermarket caps

if 1 coil pak tested good at 11k ohms and the other tested nothing it is bad and you did the test correctly.

 

I will check I may have a good ignition coil for position 1 and 4.

it could be you have bad wires and could replace the wires using splicers and new wire.

 

Yes, all of them tested 0 ohms and they look original.

 

Okay Just let me know. I'll try to replace the wire.

 

So I got new ignition coils.
2&3 have a great spark
1&4 I don't have spark but when I turn the ignition switch off it sparks. Don't know where my problem is. TCI box?

 

Can someone help

 

Can you swap the connections for the coils and see if 1 and 4 spark?

the fact that it sparks when you turn off the ignition makes me think the coil is good

so if the problem follows the input then it is either wiring or TCI I would think

 

Maybe not wiring since it sounds like it is getting energized. Sounds like the TCI isn’t doing its job

 

I read a coment on Facebook about disconnecting the black/ white wire that goes to the TCI box. So I did that and now I have spark, I plugged back and still have spark but my bike won't start. I pulled out the spark plugs and poured some gas on all the cylinders and still the bike won't start and I had some small backfires smal and a loud one.

 

So after long time I went back to work on my bike and I don't have sparks again ( I bought new ignition coils) , so I checked my pickups coils and my and the reading is nothing. So that means my pickups coils went bad? Does anyone knows different ways to make sure if they are good or bad? Thanks.

 

Pickup coils are pretty rugged. And the odds of both of them going bad at the same time are astronomical.

I think you need to go through a proper end to end check again.

https://xjbikes.com/forums/threads/how-to-ignition-troubleshooting.21932/

 

So I used another tester and that one says my pickups coils are reading 634 and 615. When I crank the engine I don't have sparks but when I turn the ignition switch off it sparks. My thoughts is maybe my TCI box is bad. Can I send it to you so you can see if it's working?

 

Not really. I don't have a test rig for these, and, on my XJ, I'm using a Microsquirt ECU for fuel and ignition.

Did you run through the all the diagnosis steps?

 

Yes I did.

 

So I bought a net TCI box and is working fine. Now the bike won't start because it doesn't get gas to the cylinders bit I have gas in the carburetors. When I rebuild the carburetors I didn't work with the air fuel mixture screw because I didn't know about it, so I'm wondering if that's my problem now.

 

FINALLY after months my bike is running. I didn't work on it for a couple months but today my father in law surprised me with the bike running. The problem is that is running rich and doesn't idle well. So my question is, do I have to adjust the air-fuel mix screws? When I crean the carburetors I didn't know about the air-fuel mix screws so I didn't clean that. Is that how you adjust how rich or lean the bike runs?

 

the mixture screws have a little o ring on them that should be replaced.
the mixture screws adjust the mixture. when you turn them in the mixture leans. when you unscrew them the mixture richens.
if your o rings are not sealing mixture may not change..

turn in to a soft bottom then unscrew 2-1/2 turns as a starting point.
also count the turns in when you start this process.


color tune tool is a way to visually set mixture.
you can also adjust and look at the plugs. this is called plug chops

 

I found that my father in law put the coils in opposite positions in the bike and I thought that was the problem why it wasn't running perfectly well so I took the ignition coils out and put them in their right positions but now the bike won't run. This is so rare and I don't know what to do now.

 

did you connect the correct connectors to coils? and caps to proper plugs?
1 coil goes to 1 and 4 cylinder 2 coil goes to 2 and 3 cylinder

 

If I connect the correct connectors to coil the bike won't start but when I don't the bike starts right away. If I connect orange and (red and white) connector with the same color it won't start but if I connect orange and (red and white) with gray and (red and white) the bike stars right away. I have a video but I can't upload here because is too big.

 

that is because the coils are in the wrong side of frame to make wires match. it is ok that they are where they are as electricity does not care what color the wire is.
as long as it starts and plug wires reach proper plugs your good.