Chaparral backfiring a lacks power

[Zland]

I Need some help.
I have a 2016 Chaparral Ski/Fish 4.3 MPI 80hrs. The trouble I am having is that it lacks power out of the hole and acceleration after 1/2 throttle. It appears that I cannot get over 3400RPM. It purrs like a kitten at idle but intermediately backfires at 1/2 or more throttle. I have completely replaced the fuel and the results remain the same. I located the sensor on the back of the distributer was not plugged in and cannot find the wire that would go into it. I researched that this sensor is only used in certain years and it might not be required.

Has anyone else delt with this or have a recommendation before I start switching out parts?

Thank You

 

[alldodge]

When asking a questions its always best to list the motor serial number

The dizzy connector is a cam sensor and is not used on your motor.
Measure fuel pressure at the rail, 43 psi
Also replace the dizzy cap and rotor

Being a 2016 means you have CAT exhaust and most likely the motor is in limp mode do to a fault code. Need to get it scanned for codes by a dealer, one from Rinda. Rinda sells Dicom software and Techmate pro

https://www.rinda.com/marine/marinemenu.htm

 

[QBhoy]

Sure sounds like a running lean issue...did you replace the entire contents of the fuel tank so there is zero chance of water still in there ? Could also be the dip cap...being the one that is known to be terrible

 

[racerone]

Use a timing light one cylinder at a time.----Might help determine if it is an ignition issue.------How did it run for you last season ?

 

[Zland]

When asking a questions its always best to list the motor serial number

The dizzy connector is a cam sensor and is not used on your motor.
Measure fuel pressure at the rail, 43 psi
Also replace the dizzy cap and rotor

Being a 2016 means you have CAT exhaust and most likely the motor is in limp mode do to a fault code. Need to get it scanned for codes by a dealer, one from Rinda. Rinda sells Dicom software and Techmate pro

https://www.rinda.com/marine/marinemenu.htm

Thank You. SN 2A451368

 

[Zland]

Use a timing light one cylinder at a time.----Might help determine if it is an ignition issue.------How did it run for you last season ?

Thank You. It was somewhat the same at the beginning of the season but knew it sat for awhile. It seemed to come out of it during the season but something just seemed like it wasnt right.

 

[440roadrunner]

Don't discount the possibility of basic things like low spark energy (failing coil, etc) or a worn flat cam lobe. It DOES happen

 

[alldodge]

Thank You. It was somewhat the same at the beginning of the season but knew it sat for awhile. It seemed to come out of it during the season but something just seemed like it wasnt right.

Might be fuel pressure

 

[Grub54891]

Had two with similar issues at the shop in the last couple years. Both had everything replaced, caps rotors wires, fuel systems checked, before they got to me. Turned out the sparkplugs even though they looked almost perfect. Replaced them myself and did sea trials on both, Perfect! Sometimes It's the simple things....

 

[QBhoy]

Thank You. It was somewhat the same at the beginning of the season but knew it sat for awhile. It seemed to come out of it during the season but something just seemed like it wasnt right.

Typical symptoms of diz cap issue on the mpi. Especially shows after storage.

 

[kenny nunez]

2X s with Grub! That is the exactly the same way my Donzi MPI acted. It had been in storage when I bought it and the Rinda showed that it only had 30 hours and never had any fault codes. Replaced the cap and rotor. After going through the fuel system and even having the fuel injectors flow tested it just would not turn more than 3500. Went to NAPA and told the counter guy I want the best spark plugs for the application. 5000 @ 70 was the result.

 

[Zland]

I appreciate everyones help.

I ended up doing a good tune up withPplugs, DCap, Rotor, and Fuel Filter. Heck, I even through a can of Sea Foam Marine in the fuel tank. Night and Day Difference. It runs like it never has before.

It took two weeks of multiple tools to get the fuel filter off. I ended up disconnecting the fuel lines and pulling the whole mount, mounted it to a 2 by 6, purchased an all steel multi size oil filter tool from craftsman, and breaking it loose. All the pain was worth it!!

Hope this helps someone in the future.

 

[Bondo]

It took two weeks of multiple tools to get the fuel filter off. I ended up disconnecting the fuel lines and pulling the whole mount, mounted it to a 2 by 6, purchased an all steel multi size oil filter tool from craftsman, and breaking it loose. All the pain was worth it!!

Ayuh,..... Welcome Aboard,..... Maybe ya oughta change it more often,.....
Once a season is pretty minimal,.....
Examine the contents to get a jump on water in the fuel,.....

If ya have a plastic zipper freezer baggie with ya,....
Crack the filter loose, slip the baggie 'round it, spin it off, 'n zip it up,....

 

[Scott06]

I appreciate everyones help.

I ended up doing a good tune up withPplugs, DCap, Rotor, and Fuel Filter. Heck, I even through a can of Sea Foam Marine in the fuel tank. Night and Day Difference. It runs like it never has before.

It took two weeks of multiple tools to get the fuel filter off. I ended up disconnecting the fuel lines and pulling the whole mount, mounted it to a 2 by 6, purchased an all steel multi size oil filter tool from craftsman, and breaking it loose. All the pain was worth it!!

Hope this helps someone in the future.

Had the same issue on my boat when I got it had never been changed. Had to cut the filter in half grab jagged edge with vise grips and hammer on vice grips to break it loose.

Changing it annually since no issues