82 maxim won't run... help

Ok guys, so my friend just bought an 82 xj maxim 1100. It was running fine thursday. He went to startup this morning. It would crank but no start up. He kept on trying to get it to start and nothing. Well this drained the batt so we put a charger on it and set the charger on "start up". We cranked it and it wouldn't start. We let off the start button it backfired out the exhaust... It did this the next few times we tried it. So we stopped for the night. Any ideas guys???

 

Sounds a lot like what was being discussed in this thread... http://www.xjbikes.com/Forums/viewtopic/t=150.html

Try some ether (starting fluid) and see what happens.

 

It sounds like you are not getting spark while cranking. Your coils are not collapsing the fields to induce the high voltage during cranking but when you stop holding the button, they do collapse causing the spark. The ignition system is a "waste spark" system. That means that two cylinders receive spark at the same time. One just before top dead center (TDC) of the compression stroke and the second at just before TDC of the exhaust. The air/fuel charge is passing through the cylinders into the exhaust system. When the spark is produced, it ignites the fuel in the exhaust system. This indicates that the coils are getting the 12 volt primary voltage, but it is not being triggered off by the TCI module. Could be the module or possibly wiring to it. Check all connections to make sure they are clean and tight. A little very fine sandpaper or emery board can be used to clean the terminals so that they shine. Coat with dielectric grease to keep clean. Keep us posted as to progress.

 

Thanks. That is what i thought it was. But I wasn't sure if this was a waste spark system or not. His fuse box is the original and it is all messed up... broken tabs and stuff. I figured that the fuse wasn't fully engaged all the time. He bought a new fuse box from napa and we are going to change it out this afternoon and check all the wiring.

One more quick question... The fuel petcocks... Is the tab what it is on or is it opposite the tab is what it is on?

 

The long tab on my 550 points to the selected position. If you take a careful look at the lever there should be an arrow on it to indicate position. Mine is on the narrow edge of the lever near the end.

 

Thanks JFStewart... You have been lots of help... I will let you guys know how it goes...

 

Just one more point... With electrical problems you must ensure that the power source (battery) is good. If the cranking voltage is too low, less than 10 volts, you can experience this symptom. Once all the connections are verified , check the battery voltage while cranking the engine. If you know the battery is good, the starter could be drawing too much current and not leaving enough battery to cause the spark.

 

Well they bought a brand new battery 3 weeks ago when they bought the bike, so I don't think that is the problem...

 

Well we wired up a new fuse box and it is still doing it. It seems like when we hit the start button that the coils arent firing and as soon as we let off of the button it sends a spark and we get a backfire... What could cause it to do that?

 

OH yea... I ran my meter on the coils, I got 3.o homs on one and 2.6 on the other. Do you think he could have a bad coil because it is reading low???

 

First off make sure it is getting fuel. Then make sure the fuel is good to begin with.

Next, make sure it is getting spark.

Then make sure you don't have any vacuum leaks.

Why are you going off into the wild blue yonder about changing coils when you haven't even checked the basics yet?

 

We have checked the basics... We know for sure that it is getting fuel... It cant back fire without fuel... We know for sure it is getting air... We know for sure it has a good battery (brand new with a fresh charge on it) The gas is only a week or so old... We tried starting fluid... We knew there was a problem with the fuse box so we changed it out... Unfortunately that problem wasn't the cause of our no start/backfire problem... There are cracks in all of the boots between the carbs and the engine... Do you guys think this could cause it? I find it hard to believe its the boots because they were cracked when he bought it a few weeks ago and it has been running excellent until he turned it off the other day and now it won't come back on and keeps backfiring if you crank on it for a little bit...

 

Did you check the cranking voltage? If the starter is pulling too many amps, the voltage at the battery will be low (below 10 volts). That low voltage can cause the symptom that you are currently experiencing.

 

To answer the question, "Why?" read my earlier post from a few days back.

The cracked boots on the plugs can cause a missfire particularly under load (acceleration), but usually don't prevent starting unless they are terrible. If the bike ran OK before with the boots, its unlikely they would just suddenly fail. If they were the cause you should get spark jumping from the plug lead to the head. It sound like you don't have spark during cranking at all.

 

check all your electrical connections for corrosion.....

 

No we didn't check the cranking volts. If it is low at the battery durring crank, what would be the prob the bat? Like I said earlier, it is a 2 week old battery and we pulled it and charged it sunday evening. Could it be the starter messing up and pulling to many amps trying to roll?

 

If it's too low during cranking it could be the battery, the fuse box, possibly the starter (although not too likely), or bad connections along the way.

Measuring voltage during cranking first at the TCI box (R/W to B), and then, if it's low, at the battery, will help narrow down the cause.