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View Full Version : Help! 2000 Challenger Not Starting when HOT!



onextremetahoe
06-21-10, 08:23 AM
I have a 2000 Challenger 2000 with the Mercury 240. I went out fishing this weekend and got out there and did a drift then tried to start and it would not go. I finally got it going so I drove to the dock and shut it off and tried again and same thing, just kept turning over. I let it sit about a half hour and it fired right up. I took it back out and it ran great. Just wont start when it is hot. Any ideas?

WAJetboating
06-21-10, 02:43 PM
Fuel vapor lock? Next time it happens, loosen the fuel cap and let any pressure within bleed off. Then reseal the cap and try starting again.

Does it happen no matter how long the engine has been running? Or does the engine have to have been running for a while? Can you start it, stop it after ~30 seconds, and fire it right back up?

onextremetahoe
06-21-10, 02:55 PM
I will try tonight. I only ran it for over 20 minutes then shut it off and tried to start it up to see if it would start.

I read on here someone else had issues and it was the Engine temp sensor, so the computer did not know the motor is haot and floods the carbs?

WAJetboating
06-21-10, 03:06 PM
I will try tonight. I only ran it for over 20 minutes then shut it off and tried to start it up to see if it would start.

I read on here someone else had issues and it was the Engine temp sensor, so the computer did not know the motor is haot and floods the carbs?

There are lots of possibilities, but first we need to know more about how it behaves. That's why I asked about the short runtime test... we need to know if it happens every time regardless of engine runtime/warmth, or only when the engine has been running for a while.

FYI, the ECU normally enrichens the mixture (i.e. lengthens the injector pulses) during startup unless the temp sensor says the engine is up to temp. However, you would normally get a hint of starting even if it didn't start "normally".

Finally, you said you have 240EFI. That's a fuel injected engine that has no carbs to flood. My suggestions are based on the 240EFI. If you instead have a carbed engine (probably the 210 carb), please say so because our advice may differ.

onextremetahoe
06-21-10, 03:20 PM
It is a 240, I just smelled a lot of fuel when I was trying to get it started. It did pop while I was trying to start but not enough to get it running. The motor does smoke at idle and through no wakes but cleans up as soon as you go. It really smoked a lot when I finally got it fired that's why I was thinking too much fuel.

WAJetboating
06-21-10, 03:57 PM
The motor does smoke at idle and through no wakes but cleans up as soon as you go.

It shouldn't smoke much at all when just idling. Are you using Mercury/Quicksilver Premium Plus oil? The original owner of my boat was using some el-cheapo 2-stroke oil when I bought my boat and it smoked (and stunk!) a LOT. Switching to Premium Plus solved that. Just a thought.


It is a 240, I just smelled a lot of fuel when I was trying to get it started. It did pop while I was trying to start but not enough to get it running. It really smoked a lot when I finally got it fired that's why I was thinking too much fuel.

That does makes the engine temp sensor a prime suspect. Run the test I suggested - try restarting while the engine is still very cold, see if the symptom still exists.

onextremetahoe
06-21-10, 07:22 PM
I actually just got the boat and I am trying to run all the oil out so I can put oil in that I know will work.

I ran the test. The boat started everytime! I started it shut off in 30 seconds and it fired right up. I started it turned on the water let it run for about 10 minutes shut it off it fired right up?:confused:

onextremetahoe
06-28-10, 06:41 PM
Any suggestions?

johnhibbs
07-09-10, 01:28 AM
I have the same engine and the same problem. My next thing to try is replacing the temp sensor. I tried a new starter and new ignition switch.

Trick to start: Turn the steering wheel hard CW or CCW to give the engine a little more gas and it will start that way. When you turn the steering wheel like that on a Mercury/Challenger it revs the engine. You can also remove the driver's side compartment and reach in a pull the cable linkage that is connected to the steering wheel. That will give it as much gas as you want to start it.

onextremetahoe
07-12-10, 07:57 AM
Just wanted to follow up with my issue. I replaced the Head Temperature Sensor and it starts every time!

Thanks.

johnhibbs
07-12-10, 12:58 PM
I see two parts in the engine diagram. One is the sensor assembly - temp (port) PN 13536A14. The other one is the sender-temp (starboard) pn 974651. Can you tell me which one you replaced?
Thanks.

onextremetahoe
07-12-10, 02:08 PM
PN 13536A14 cost me $30 at the local Mercury Dealer

johnhibbs
07-12-10, 03:33 PM
Great. I'm off to the Colorado River tomorrow. Maybe I can pick one up today.

pc4k
07-12-10, 05:45 PM
Maybe this is what is happening with my 2003 Utopia 205 w/ 240hp Merc? Starts right up after short runs, but when you run it for 15-20 minutes, it won't kick over. Was wondering if it was a heat sensor or something. Hmm...

johnhibbs
07-12-10, 06:01 PM
I just got the temp sensor so I will report back in a few days how things went.

johnhibbs
08-12-10, 11:35 AM
I have the new temp sensor installed and the hard starting problem has finally gone away. I ran the boat all day with probably 15 restarts and no problems.

johnhibbs
09-19-10, 12:49 AM
Onextremetahoe,

Have you noticed an increase in your gas mileage after replacing the temp sensor? I could swear I'm getting a huge improvement in my gas mileage. The manual says that the temp sensor (via the ECU) can increase the fuel mixture by 40%.

LeeZeitvogel
06-07-11, 11:34 PM
where are you finding these part numbers, book or web page and if web ? where at (give link) thanks, mine was hard to start twice this weekend while pulling skiiers.

johnhibbs
06-08-11, 12:50 AM
PN 13536A14

Any Mercury dealer should be able to look it up for you. You can google for it too.

johnhibbs
06-08-11, 12:54 AM
Do a search on this site for this thread also: " Best and easiest "tune up" / performance boost for 240EFI engines..."

surferdavet
07-06-11, 06:53 PM
I had the same problem with my 2001 Utopia with the 240 EFI motor which I bought used - ran fine but when hot would refuse to start. Cooled off - start right up. I traced the problem down to a short in the ignition switch which was causing the motor kill circuit to ground when hot. I replaced the switch and its integrated harness (which plugs into the harness back at the motor) and also replaced the engine kill switch for good measure while I was at it.

Haven't had a problem since. Might be worth checking out.

marcha10
08-28-11, 01:13 PM
Any suggestions?

Writing from Austin, Tx. We've had a similar problem. Just fyi, we did replace both temp sensors on the head and the problem still exist. We have a 2000 Speedster M2 240. Just read in another article that they replaced the tps sensor and the boat runs like a charm. We haven't tried that yet, however we're going to test the voltage on the tps before making that $500 mistake...Keep us posted as we will be back to see how your problem is going. We will post as well. Thanks!

WAJetboating
08-28-11, 01:53 PM
If you have access to an oscilloscope, use that to test your TPS. You need to watch for "glitches" in its resistance as you turn the wiper. These will not be visible on a digital meter and likely not on an analog meter either.

Hope this helps!

LeeZeitvogel
09-16-11, 10:18 PM
So I have the same issue and I replaced the plugs and temp sensor, but what is a oscilloscope? and where is the TPS sensor ie. what does it do?