my 1984 fj wont start when hot

[fjman]

I have a 1984 yamaha fj1100. It won't start when engine is hot. But when its cold the thing fires right up. You have to wait for 30 mins or more to let the engine cool down. It is very frustrating on my part. any help would be appreciated 

[oldktmdude]

  Does it push- start when it's hot? If it push-starts easily when hot, I'd say you have a problem with your starter-motor. Bad or loose lead connection or your starter may need cleaning, servicing or replacing. I had similar a problem with my '85 and fixed it by replacing the starter. It's been fine since.

[FJmonkey]

Some relevant info would help.
1. Does the engine it crank over with the starter when hot?
2. Does the engine not even turn over?
3. If it cranks over is the speed sound the same when cold(er) or does it seem slower?
4. How old is the battery?
5. Has the battery been maintained well and kept on a battery tender?
6. Does the bike sit for long periods between Kookaloo moments?
7. What happens when you crack the throttle open about 1/8 while hot starting?
8. Do you use dino or synth oil?
9. What tires are you running on?
10. Have you ever hit a pine cone while leaned into in a corner?
11. Is your bike voting Democrat or Republican?  Strike that, might get banned for stirring up that kind of steaming pile of debate.

My 86" hates to hot start and the throttle thing seems to fire it right up for some mysterious reason. 

[SlowOldGuy]

I love this kind of post.

"My bike won't start.  Anyone know whats' wrong?"

If you don't have the time to supply the details, I don't have the time to help you.

DavidR.

[andyb]

Won't start hot? 

It's broken.

Fix it.


(More info = helpful.... there's also about six threads that cover the typical hot start problem that FJ's get, amazingly you're not the first person to have the issue on a 20+ year old bike.....)

[fjman]

1. Does the engine it crank over with the starter when hot?
yes
2. Does the engine not even turn over?
by turnover you mean fires up right? No it does not turnover
3. If it cranks over is the speed sound the same when cold(er) or does it seem slower?
the speed is the same. fast
4. How old is the battery?
about a month old
7. What happens when you crack the throttle open about 1/8 while hot starting?
nothing happens
10. Have you ever hit a pine cone while leaned into in a corner?
hahhaa not YET
.

[Harvy]

1. Does the engine it crank over with the starter when hot?
yes
2. Does the engine not even turn over?
by turnover you mean fires up right? No it does not turnover
3. If it cranks over is the speed sound the same when cold(er) or does it seem slower?
the speed is the same. fast
4. How old is the battery?
about a month old
7. What happens when you crack the throttle open about 1/8 while hot starting?
nothing happens
10. Have you ever hit a pine cone while leaned into in a corner?
hahhaa not YET
.

Sounds like that have eliminated the starter and battery as the problem.

Next questions.......
Do you have original fuel lines?
Do it have a fuel filter in fuel line?

Early FJs were quite particular about fuel line type and routing........it may be suffering from fuel starvation due to the fuel vapourising in the line, partricularly when the line is heat soaked after its been sitting for a short time when you stop for a smoke or to re-fuel.


Harvy

[fjman]

Do you have original fuel lines?
nope.
Do it have a fuel filter in fuel line?
it doesnt have one

after riding for 15 mins or so.. it starts right up

but after riding for about an hour.. it wont start.

[Harvy]

after riding for 15 mins or so.. it starts right up

but after riding for about an hour.. it wont start.

15 mins riding is not really telling you much.......she is really only just coming up to temp.......the 1 hour ride is a better timespan.

Seems from the pic in the next post that it has been modified somewhat (well paint anyway)....do you know any other history on it?
If I recall correctly, the early models had a fuel line routing diagram either under the seat or on the inside of the rear mudguard?

If its not original in that department, the routing could be causing the heat soak situation.....

Or I may be completely off course.

Electrics can be affected by heat as well........ have you check for spark when it won't start?

Harvy

[fjman]

I tried checking for spark after an hour riding. Its as strong as when the engine was cold.

[Flying Scotsman]

Carbs need looked at.

[Adam FJ]

Try opening the fuel tank lid and then starting.

Adam.

[Mark Olson]

next time it does it , open one of the float bowl drains and see if fuel comes out. If no fuel you have a vapor lock problem or a fuel line routing problem.

[RichBaker]

Do you still have the carb heatshield (sandwiched foam/foil piece) between the carbs and cylinder?  If not, the carbs are probably vapor-locking...

[Musonee]

 
I have the same problem with my 84 FJ1100, with the difference that the fuel line is modified with a filter and a tap.
When the engine is hot, it runs slow (the starter is in good shape and the battery is new), looks like it gets tight.
If I let it go down hill on second gear it will start running immediately.
Thanks fore any help.