Gets up to operating temp and dies

I went for a short ride and a not so short push back home. I let the bike run for a short time before I went for a ride, when it got to full operating temp it died and did not want to start back up. Can I get some ideas of what to check. I do pretty good at R&R parts but stink at troubleshooting. Thanks for all the help

 

Ignition pick-ups or colis are failing. Run the bike in the driveway and when it quits attack it with a meter to see which part is going bad. Take some readings beforehand with it cold to compare to readings when hot.

 

I forgot this tidbit of info 1982 XJ 750 Maxim
Thank You I do appericate the info and the quick response. I will get on that this weekend Thanks again

 

You need too determine if its Fuel or Ignition related.

I'd have a look at the Alternator Brushes. Easy to do. 10mm limit.
If you haven't done so, ... replace the Fuse Panel.
See if you have Spark when the bike stalls.
Clean the Kill Switch.
Break the Battery down; see what the Cranking Amps are.
Try running the Bike on Prime.
(Or Reserve)

Does the whole Bike go dead or it just won't start?

 

I will second that its most likely the pick up coils on the left side of the crank. Replace those with a known good set and you should be set to go. To check if its fuel related, when it dies unplug a spark plug cap from spark plug. With spare spark plug rest it against the head. DO NOT HOLD IT THERE, you might have a shocking time. If you get a white spark then its most likely fuel related, if you get a weak or no spark then it's ignition related. But like I said, its most likely the pick up coils.
Sean

 

We have no symptoms except "won't start."

Could be electrical.

Could be fuel.

Could be a few dead tight valves.

Could even be as simple as a plugged gas cap vent.

We need to know more about the patient to make a good diagnosis...

How many miles on the bike? Mods? (Pod filters, aftermarket exhaust, etc?)

 

My 2 cents.

Make sure it doesn't have a fuel line that gets soft as soon as it warms up and folds at a bend...

I bought a bike once that did that...PO had put freaking clear vinyl tubing on for fuel line! Duh.

 

How do you come to the decision that the Pick-up Coils are to blame?

Those Pick-ups are the simplest of parts on the Bike.
Magnetic Pick-up's. They rarely ever go bad.'

I'd blame the TCI before suggesting to swap Pickup Coils.

With the information we have about this bike suddenly coming to a halt without being able to do any hand-on testing, we don't really know what it is.
We just give the most likely problems to check.

I'd place the Pickups on a list to be checked, sure.
But, you usually find the Pickups working fine.
They have the factor of simplicity working in their favor.

 

Probably because of the description....in cars, the crankshaft position sensor (which is a glorified term for mag pickup coil) is known to act this way on a lotta cars...the windings around the mag that sense the field develop a small break that only opens the winding when the motor comes to full temp, and then it stalls and won't start again until cooling off.

I have to admit it came to mind, but I'd like to know some more about the issue first too...

 

Thanks for all the good ideas to check. ok first it has 30,000 + miles and all stock. the first 4 - 450 miles it ran great the last 25 - 50 miles is when this problem of running like it had run out of gas started I know the tank was nearly full the first time it happened, we sat for a few minutes it started up so we finished the ride to where we were going. on the way home no problems. begining of the ride it was 90 plus on the way home it was about 80 so I thought it was a vapor lock. then a few weekends ago I went about 5 miles it ran great, on the way home about 1.5 miles it quit running let it sit a few minutes got about a mile it quit again this time no matter how long I waited it would not start so I pushed it home. The best way I can describe it is like it's running out of gas. this last time it happened I had replaced the fuel petcock and put in about 2 gallons and it died after about 2 miles so I know I have gas I will check all of y'alls recomenditiions this weekend when I have some time. the fuse block is on my list of parts to buy, and going through all elec connections will be taken apart looked at cleaned where needed (proably all will be cleaned) and dielectric grease applied Thanks again for all your help

 

30,000 Miles, ...
Alternator Brushes.

Your Battery recovers enough to get you going.
The Charging System can't keep up because the Brushes are too short.
The Battery does not get charged.
You "Live" off the Battery until you run-out of Amps.
Then, you die.

 

Ok thanks Rick I will check that also the PO said he put a new battery on it so I did not even think about brushes or the battery being a problem Thanks again

 

First lesson: NEVER BELIEVE ANYTHING THE PO told you (unless you're related and then still be suspicious.)

Next: Do you have first hand knowledge or any hard evidence the valves have ever BEEN TOUCHED? Not the PO's word, knowledge or receipts?

Rick is right, at 30K the alternator brushes are probably mere nubs of their former selves.

You can't just latch onto a bike that old and start riding it; things are gonna go very bad for you. Sure, it lasted for a while but the neglected maintenance is GOING to catch up and it sounds like it has started to.

Read this: http://xjbikes.com/Forums/viewtopic/t=24010.html

And know this: 30K is the mileage at which a completely neglected XJ will start to experience multiple failures; if the valves haven't been touched; the alternator never attended to; the brake fluid/lines/seals never replaced--- it's going to start "having problems."

They're not "problems" and they're not your fault-- you have a quarter century worth of neglect to reverse.

Have at it; you sound like you have the aptitude. There IS a learning curve; but it's fun once you GET A MANUAL and dive in.

Welcome aboard. We've been there.

Now go check those rear brakes before you ride another mile. http://xjbikes.com/Forums/viewtopic/t=15874.html

 

Thanks I realy like this forum all of you all are very helpful. I have a long list of things to order, some I already have the head bearing conversion kit, to fix that annoying catch, master cylinder rebuild kit, caliper rebuild kits, brake lines (SS) fuel petcock these i have purchased Len has been great. I have 3-4 more parts orders rear brakes are in there and next summer should be problem free, or at least minor stuff. I don't like payments of any kind so a new bike is out of the question and I do like wrenching and it has been awhile since I been riding and yeah I am going through that learning curve again this is the newest bike I have owned. Thanks again

 

Dude check my sig. I still ride the Norton.

New bikes have too much plastic and are bloody uncomfortable, truth be told.

Sounds like you're on the right track. It's worth it.

 

Here's the List:

Engine Oil / Filter
Final Drive Oil
Air Filter
Brakes (Complete / Especially REAR)
Clutch Adjustment
Brake and Shift Pedal Pivots / Lube
Center & Side Stand / Lube
Swing-arm / Lube
Front Forks / Fork Oil
Steering Bearings / Pack or replace.
Wheel Bearings
Battery
Brake & Clutch Pivots / Lube
Alternator Brushes / New
Valves / Check
Fuse Panel / Replace
Fork Springs / New

 

Rick, oh master of all things carburetor, you left CARBS off the list!

Carburetors cleaned/ bench sync/ float levels checked/ vacuum sync.

Careful inspection of fuel and vacuum lines for cracks/ splits.

Inspect intake manifolds to ensure the cracks you almost certainly have do not go all the way through.

 

the cam sensor does the job of the old style mag pickup on cars. all the crank sensor does is tells the computer it's on top dead center. so that the computer can keep the signals from the cam sensor in check.

course, they both pretty much work the same. so i guess in reality you could call them both pickups. one just works more then the other.

but like rick says. they're built with simplicity. on and off switchs that either work or they don't.

the only cars i experienced that run cold and quit when warm. were bad fuel pumps. OR, in the case of fords. bad ignition control modules mounted on the side of the distributor. EEC IV module was notorious for that problem.

i never had the fortunate circumstance of running into a bad crank or cam sensor. but i'm not saying that it don't happen.

 

Don't wanna get into a pissing match over car repair, this isn't the place...but I have 30 years of shop experience, so it's hard for me to resist. Your description of crank+cam trigger is a pretty recent design, relatively. So I understand where you get that, yes cam trigger signal will suffice if the CKP fails while running on NEWER cars....I replaced a TON of failed CKPs that caused the heat soak stall condition on older GM, Ford, etc...back when it was the sole source of timing signal for injectors and ignition.

Old GM's used to lose their bead on #1 TDC because of this and sneeze sometimes when you tried to start them and have long cranking times, until the ECM found TDC again...

Come to think of it, the old Hall Effect sensor in the dizzy on early 80's Chrysler was known for this kinda stuff too....looked very similar to the unit on these bikes.

 

amfmtxca,

Have you found any thing yet?

MN