New to me challenger, cold start and varying RPM questions

[jdhuggar]

Hello,

I recently bought a 2007 challenger 180 with 71 hours on the boat (according to the display). The boat has a little bit of a starting issue. It first happened two days ago after being anchored for awhile. The boat did start, but a low battery voltage came up on the display after finally starting. Today I hooked up the battery charger to the boat and it again had trouble starting, but did start after 5-6 attempts (held down the start button for 4-5 seconds on each attempt). The RPMs when cranking was about 450. Does this sound normal? I have already replaced the spark plugs, which did not resolve the issue. The low battery voltage did not appear on the display after starting. Anything I should look into first when trying to track down this issue?

I also have an issue where the RPMs are varying when the boat is running at any throttle. It was varying about 100-150 rpms (so it bounced between 4500-4700). Since changing the spark plugs it bounces around 70 rpms or so. Is this normal for this type of boat? Anything I should be looking into? This is our first jet boat, I'm more used to outboards.

I plan on having the SC rebuilt in the next week or so (really hard to do with all this nice weather we're having, but I heard they're a time bomb!)

Thanks in advance!

 

[xintersecty]

Check the age on your battery, it might be time for a replacement. My last battery lasted three seasons.

 

[jdhuggar]

Well I changed the battery, and changed the oil (it was a little high on the dip stick, now in the middle) both of which didn't help the problem. I changed the fuel filters and the cold start problem has gone away completely (knock on wood).

It seems like the engine still varys RPMs. Is this normal for a 4tec engine, or is there something else I should try?

 

[C9R0J0]

I don't know if it's normal or not either, but my 06 Challenger I bought about a month ago does the same thing. The RPM varies 50-100 at certain throttle settings.
As far as the starting goes, it usually starts better cold than warm, but that's hit or miss too. Sometimes it starts almost instantly, other times it turns over 3-4 seconds before starting. Battery is new so I'll have to check the fuel filter.

 

[Eclipse1701d]

Difficulty starting, when hot, could be worn starter (heat=expansion), or hydro-lock from leaky exhaust manifold.

 

[C9R0J0]

The engine turns over fine, it just doesn't fire right away. It only does this occasionally.

 

[jeffrt]

I've only had my 4 Tec for a month or so, but I've noticed that the rpms fluctuate a bit too. Nothing major though.