Challenger 2000 w/240EFI bogs down

[nenikol23]

2000 Challenger 240 EFI.

We take it out every 6-8 weeks. Last time we took it out was December 2nd 2021. Ran perfectly fine.

Took it out yesterday, after 5 min on the water, throttle somewhere midway at around 20mph, engine started cutting out and coming back to life. If I don't adjust the throttle, engine sounded a lot more low pitch. Turned it off and couldn't get it to start back up. We got towed to the dock, 10min later, it started back up.

Where to start?

 

[Tim75]

2000 Challenger 240 EFI.

We take it out every 6-8 weeks. Last time we took it out was December 2nd 2021. Ran perfectly fine.

Took it out yesterday, after 5 min on the water, throttle somewhere midway at around 20mph, engine started cutting out and coming back to life. If I don't adjust the throttle, engine sounded a lot more low pitch. Turned it off and couldn't get it to start back up. We got towed to the dock, 10min later, it started back up.

Where to start?

We have to start with exactly what year engine you have. Hint- is the flywheel cover round or square-ish? Changed about 2002½.

What is the max RPM you get? Are you using the OEM spec NGK plugs? Other brands cause problems. Have you checked the kill switch? The OEM units cap failing to hold the center plunger depressed. That kills the engine. Do you have the throttle guardian? Small black box about 1x3x4 inch in the driver helm box. They have been known to cause multiple issues.

Have your injectors ever been serviced? They are 20 years old and only occasionally used. They can stick open, causing flooding and hard to restart. And using lots of gas. They can also stick closed or have bad spray pattern. The worst situation is stuck closed. That cylinder does not get gas OR OIL. This can lead to a meltdown in that cylinder. BTW, what is your fuel system pressure? Is it steady or fluctuating?

Notice a pattern? This is just a few of possible problems.

 

[nenikol23]

Hi Tim, here's some clarifications to your questions:

- Flywheel cover is ROUND
- I use the OEM spark plugs (changed in June 2021)
- Max Rpm 6000
- Throttle guardian has been removed
- Injectors were replaced in February 2021 (boat was barely running prior to replacement of injectors, would not start, start with high idle, inconsistent idle, bugg down)

I have not checked the fuel pressure yet. My priming fuel pump was also replaced back in February 2021.

 

[nenikol23]

Reporting back after new findings. I have a significant fuel amount leaking from the bottom of the throttle body. The engine cranks but does not start, sounds dry. Injector stuck open?

 

[Tim75]

Reporting back after new findings. I have a significant fuel amount leaking from the bottom of the throttle body. The engine cranks but does not start, sounds dry. Injector stuck open?

As you take apart, look for:
cracked fuel rail (plastic).
Nicked or cut O-rings, at fuel rail and each injector. Of course, you will replace all O-rings anyway, right? The o-rings on the injectors are special size. Hard to find except at an injector service shop.

The service manual can make this job easier with its detailed instructions and techniques. Service is about $25 each injector. New set from Merc is about $750.

 

[nenikol23]

I brought it to a shop. They said the high pressure pump inside the VST was not putting out any pressure I purchased a pump from Amazon (https://www.amazon.com/dp/B01FWUT47W?psc=1&ref=ppx_yo2_dt_b_product_details) and they installed it. When I picked it up, the guy ran it for a few seconds.

Fast forward a week later, I can't get it to start. Cranks but sounds dry.
I checked the fuel pressure at the valve, about 37 psi.
After cranking several times it started cutting out while cranking (I hold the key but it cranks then pause, cranks then pause). Then I noticed fuel coming out of the pressure valve and dripping down.

Any suggestions?

 

[nenikol23]

Since my last post:
- Cut off lanyard switch was found to be bad and was replaced

Engine starts but has to be in gear and the throttle has to be applied about 15-20%

Now another discovery. When running, it spits oil out of the exhausts. When you shut it down, there is literally oil dripping, almost leaking) see below videos I took.

What can be causing the oil leak from the exhaust?

 

[Tim75]

Since my last post:
- Cut off lanyard switch was found to be bad and was replaced

Engine starts but has to be in gear and the throttle has to be applied about 15-20%

Now another discovery. When running, it spits oil out of the exhausts. When you shut it down, there is literally oil dripping, almost leaking) see below videos I took.

What can be causing the oil leak from the exhaust?

Oil in the exhaust is from leaking/open injectors. Gas coming from the throttle body is another clue. There is nowhere for oil to LEAK from the exhaust system. Check the TPS for proper operation. When it fails (and they do), the ECU defaults to full rich to protect the engine.

It sounds like your Start-in-gear safety has failed. You will need to take the shifters out to get to the switches and magnets. Tiny wires- be careful.

 

[nenikol23]

Oil in the exhaust is from leaking/open injectors. Gas coming from the throttle body is another clue. There is nowhere for oil to LEAK from the exhaust system. Check the TPS for proper operation. When it fails (and they do), the ECU defaults to full rich to protect the engine.

It sounds like your Start-in-gear safety has failed. You will need to take the shifters out to get to the switches and magnets. Tiny wires- be careful.

@Tim75 Thank you for your continuous help and for sharing your knowledge.

I suppose the hard starting is also related to faulty injectors. Will check TPS.

Forgot to mention, the start-in-gear was bypassed by the last guy who worked on it because he figured a good fix for my no start is to tie the boat to the dock, put in gear and start with some throttle (sketchy).