2000 Challenger 2000 240 Merc Stalls above 2800 RPM

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Hi Guys,

I recently purchased a 2000 Challenger 2000 with a 240 Merc EFI. It needs love and some elbow grease and it will be a great boat!

I just need to get it to run properly first and I need your help. It has been sitting for about 6-10 months. At first it wouldn't even crank and I realized the starter was stuck. A few taps with the wooden side of a hammer and it starts like a champ, every time. The problem is, as soon as I go over about 2600 RPM, its slowly dies out, if I go full throttle, it dies out almost immediately. It start back up no problem, and runs fine up to like 5mph....any more throttle and it dies out.

This is my first ever boat so I am not too familiar with it. I am handy and I know cars pretty well (done a few transmissions, engine swaps, high pressure fuel pumps..) but I never worked on boats. So I am even unfamiliar with some components.

Here is a bit of service history on the boat from the previous owner...
May 2013 - Service troubleshooting, found high pressure fuel pump low? bad injectors. Total $358.21
June 2013 - Replaced fuel filter and Merc solenoid kit. Total $82.76
June 2014 - Starts but wont throttle in gear, replaced trigger assembly, cleaned throttle butterflies, replaced spark plugs. Total $960.25
March 2016 - Engine shutting down when warm: removed VST and cleaned fuel system and pump re-installed found Hi pressure fuel pump works intermittently, not holding fuel pressure. Replaced VST fuel pump, fuel pressure 40psi. Total $1505.14
July 2016 - Leaking fuel housing gasket. Installed new pick-up grate. Install GPS. Total $812.57
November 2016 - Stuck fuel pump due to tarnished gas. Soaked in fuel for 24hrs. Total $725.63
July 2017 - Low speed RPM ok but no high speed RPM. Removed and replaced faulty engine stator and trigger assembly. Replaced spark plugs. Replaced fuel filter. Replaced bilge blower fan. Total $1628.33
July 2018 - removed and cleaned throttle body plenum and injectors. TPS sender and HPFP. Rewired connectors to fuel pump. New battery. New spark plugs. New fuel filter. Total $1240.11

What do you guys think I should start with? Any ideas are appreciated.
Thank you!
Wow! The very definition of a a boat.

Back to basics. Have you done a compression test? Fresh battery, all plugs out, WOT. Hoping for 130psi or better. All cyl. w/in 5% of one another.

Injectors: 7 years ago. They could be having issues. I had some that were stuck open; that is they were spraying all the time while the key was on.

Ignition trigger coils (under flywheel): I don't understand all the "magic", but at 2600 rpm, there is a switching from low speed system to high speed system electronically. I had the same problem. Stumble and stalling about 2600 rpm. Replaced the trigger, and now revs to 6200 rpm. Was the timing set when trigger was replaced? Are the timing/throttle levers on port side of block working properly?

TPS: helps control fuel mixture up to about 3/4 throttle. Have you tested it? Many threads here about it. Another $550 if it's bad.

VST: are you maintaining 35-37psi with engine running? Start with filters- 1st strainer is on the bottom of fuel pickup in the tank. Next filter is on the pulse lift pump. Next is the large spin-on filter. Next is in the vst, on the bottom of the pump. Last is a strainer in the end of each injector. Are you getting fuel flow from each pump? There are 3.
Did a compression test today and I get exactly 130psi on each cylinder.
Checked all the plugs and all look good.

Took it out on the water with some tools and ran it without the cover to observe. This time, it was running with a much more stable idle at about 800 rpm. The throttle would go up until 1200 rpm and anything above that it would slowly bug out, for about 5-8 seconds then eventually turn off. It pretty much feels/sounds like a choke is on or something, despite this engine not having a choke.

Do you happen to have a link on how to test/or check the trigger coils , I cant even seem to find this part online, is that the same as the stator?

Didn't test the TPS yet.
Will do a fuel pressure test tomorrow.
Trigger is NOT the same as the stator. There are instructions for testing trigger in the service book. Avail. for d/l on this site. 6 wire connector, top of engine, aft of flywheel. Check resistance between wire pairs. Should be able to find this part on ebay. Merc has been using it on 2.5 L V6 engines for decades. Jets and outboard use the same trigger. Always watch for corroded connectors.

Also check the output voltage from the regulators. ECU is sensitive to under and over voltage 14 V is too much.

Idle RPM in the water, should be 1100.

Any chance you have any of the old parts that were replaced? I bet they are not failed.
Tested the trigger coils resistance as per Service manual, ALL OK within spec.
Tested the fuel pressure at the Vapor tank valve as per Service manual, I get 38psi.
Tested Stator resistance as per Service manual, GOOD within spec. Engine Port Side.jpgWhatsApp Image 2020-02-05 at 11.06.49 AM.jpegWhatsApp Image 2020-02-05 at 10.55.13 AM (1).jpegWhatsApp Image 2020-02-05 at 10.55.13 AM.jpeg

Took it on the water again after replacing the water separating filter, acts pretty much the same. Idles very stable at about 1100rpm , will go up to 1500-1600 rpm then slowly start to die out. Turns off, but starts right back up every time.

I noticed something during the water test. In the picture I attached below, the arm I colored in yellow does not move at all. Is that normal? I also included a few pictures of the engine around in case someone notices something unusual.

Thank you.
That arm controls the spark advance on the trigger. Setting it part of the timing procedure. That's definitely going to be a factor in the engine not revving.
Would you know what is supposed to control that arm? Should it be moving along with some other arm (like connected in a certain way or is it activated mechanically on it's own?)
The upper portion of that arm is controlled by the lower portion that the throttle cable is attached to. The screw (part c in the drawing) determines when the spark starts to advance.
Also make sure that the max spark advance screw (part d) isn't already touching the block. Do you have the manual? It lays out the timing procedure in detail, although it does require a timing light.
Hey thank you for your continuous input and help.

I do have the Service manual, however I am lacking quite a few tools that seem to be required to perform the timing procedure. It's something I'd have to do at a dealer, unless there is DIY way without the timing light and DDT.

I just can't seem to understand how that arm is supposed to move since when you give it throttle, the bottom arm moves away from the top one...I would think it should be the opposite in order for the top one to move.
Here is a link of a video I uploaded showing how it's currently set-up
It looks like the upper arm is stuck in the fully forward position. It may just be stuck. Also the adjustment screw 'c' seems like its backed out further than mine. I can't say for sure on that one since my boat is wrapped up for the winter. That screw should start out against that little tab on the upper arm. When the throttle is opened it will push the upper arm towards the rear of the boat. Try just pulling that upper arm towards the front of the boat and see if its stuck.
The upper arm is very easy to move by hand. We have tried moving it while being on the water and the more you move it towards the front of the boat it will stall the engine. Maybe I should remove the flywheel and see what's happening under there? Perhaps something not attached properly?

If I understand correctly, it should be towards the front of the boat in its "neutral position" and always be resting on the bottom arm?
Thats correct. It should always be contacting the lower arm and should be closer to the front in idle position. As throttle is applied it will rotate towards the rear. This physically rotates the trigger coils under the fly wheel advancing the spark timing. The upper arm should be under some spring tension to return it when the throttle is reduced. All that is required to set the timing is a timing light and a volt meter. Setting the .462 thing and using the dtt isn't necessary.
I removed the flywheel to inspect and try to understand what exactly happens when that thing moves. It's very new to me and I honestly do not understand how/what it does. I've attached a video of it in motion. Let me know if it looks normal?

Also, if I wanted to try to set the timing, do you know if I need to get a specific timing light or a generic one would work?



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Everything looks normal under there but the arm seems to be sprung in the wrong direction. The throttle arm may have been assembled wrong. For setting the timing, a simple basic timing light is all that's required.
I think you are right. Now that you mention it, when comparing the picture I have taken VS the sketch in the manual the Top of that arm is facing left whereas in the sketch it is facing right.

I will look into it and report back.
Once again, I really appreciate your help and input, thank you!


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I struggled alot with timing on mine when I first got it. I thought I could BS my way through it just with trial and error but no way! Once I got the timing light it took minutes and ran great. This forum helped me immensely to get my Challenger running!
So the arm in question was actually well installed, since it goes towards the engine on top, there is only one way it can be installed. (the angle of my picture is weird and misleading)

I was getting ready to put the flywheel back on today and attempt to perform timing adjustment when I found a broken oil bleed hose sitting on the engine and leaking. Furthermore the fuel line that goes to the bottom of the Vapor Separator was brittle with cracks and was leaking fuel as well.

I found a few posts suggesting to replace the bleed lines and I will do that tomorrow. However according to the diagram, there is one disconnected hose and I am not quite sure where it goes? (see attached photos)

At this point, I am also wondering if my engine dying out issue above 1500 rpm could have been caused by the broken/cut fuel and oil lines causing air into the system?


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