'95 Regal Rush XP Mercury Sportjet 120 troubles

[Jono69]

I am having some issues with my sportjet 120 motor and am in need of some help before I lose it. Here is a little backstory to help you understand what I am dealing with: I was cruising down the Miss at about 34mph and my buddy in another boat stopped fairly quickly, so I pulled back my throttle pretty quickly myself. The motor died right away. Could not get it started again. Had to be pulled back upstream to the dock. I thought I fouled the plugs, so I replaced them when I got home. It started right up with the throttle in full neutral power. And now that is the only way I can keep it running. I can ease the throttle back very slightly. Any more than that, it dies. It runs smoothly at the full neutral power setting, and I can run the throttle up at the carbs and it runs great, but as soon as I back the throttle lever back, it dies. I have changed the plugs, checked the fuel filter and lines, the carbs are clean, battery is strong, I adjusted the idler screw in and out. I just don't know. It was running perfect until that point. I am fairly mechanically inclined, however this is my first boat.
Any help would be greatly appreciated!!

 

[Jono69]

Re: '95 Regal Rush XP Mercury Sportjet 120 troubles

I have found what should more than likely be the source of my problem... I have 4, count 'em, 4 busted coils. The magnets are either broke in half or shattered. I will be sourcing parts locally if possible tomorrow. God I hope this is it. And if it wasn't, it was about ready to be. Still if anyone has any advice, it would be much appreciated!!

 

[Jono69]

Re: '95 Regal Rush XP Mercury Sportjet 120 troubles

So I replaced all four coils. It is running at full neutral power much better. But... still dies when the throttle comes back! I am at a loss.

 

[btanner]

Re: '95 Regal Rush XP Mercury Sportjet 120 troubles

I would check the control cables, throttle and spark advance to make sure something didn't slip out of position. If the cable moved off position it may be throwing something out of synch for idle. You've got a weird one.

 

[kend301]

Re: '95 Regal Rush XP Mercury Sportjet 120 troubles

Sounds like one of 3 things.
1 Disconnect the kill wire and see if it still happens ( black/yellow wire )
2 Check carb vents be sure they are not clogged .
3 Broken reid valve , you have to remove the carbs and intake to check these .

It would also help alot if you posted more info on the boat as 95 was a year of change , Do you have a CDI or CDM ignition system ?

 

[Jono69]

Re: '95 Regal Rush XP Mercury Sportjet 120 troubles

Well after toying with it for a while yesterday, I got it to run perfect. I was very happy. Shut it down, started right back up. Brought it out of the garage today, will not start at all now. It is not even trying.
Kend301... I disconnected the kill swtich at the beginning of my problems. Is that what you are refering to? Everything in the carbs is clean and appears normal. I do not know about the reid valve though. The boat is a 1995 Regal Rush XP, Mercury Sport Jet 120 (0E114853). It has the black stator. New plugs, good wires, and new coils. Good battery. "Figure 8" style fuel pump assembly which tested good. As far as CDI/CDM, How would I be able to tell which one it is?

 

[kend301]

Re: '95 Regal Rush XP Mercury Sportjet 120 troubles

You need to isolate the problem , since it will not start check for spark and fuel .
Also read the stickey post Sport Jet basics at the top of this forum , It has some test I will ask you to do anyway.
Black stator tells me you have CDI type with a switchbox. It is also your most likely suspect of this type of failure.

 

[Jono69]

Re: '95 Regal Rush XP Mercury Sportjet 120 troubles

Thanks Kend. I am going to try to tear into it some more today. I can not find my Fluke anywhere (DOH!) so I am going to borrow one from a friend so I can do the tests. I did have it running last night. However it would run for 30 seconds and shut down with no input of any kind from me. Is there a place online that you recommend to purchase a new stator should that be the issue? Boats.net has them listed as obsolete.

 

[kend301]

Re: '95 Regal Rush XP Mercury Sportjet 120 troubles

Post up results from your ohm tests and I can giude you from there , CDI electronics makes some awesome stuff for these boats , need engine serial number to get you the right one.

 

[Jono69]

Re: '95 Regal Rush XP Mercury Sportjet 120 troubles

Update: Finally had the time today to work on this thing. Kend, When I am taking the ohm readings on the stator and trigger, does anything have to be turned on? I am getting erratic readings on both. The stator readings are in the 4 M Ohm range (Red to Blue and Red to GND) and the trigger I am only getting a reading on the Brown to Wht/Blk wire. When I am doing the trigger tests, should I be taking the reading on the wht/blk wire that goes back to the trigger or the other end that goes to the switch box? Also the same question with the stator. Red from the stator to Blue from the stator??
I fiddled with everything today and I found something out. If I disconnect the Black/Yellow wire (coming out of the switch box and then into some bundles) and then start it up, the thing runs like a gem. But when that wire is connected, it will run rough, if at all. It seemed to be doing well, So I took her down to the launch on just put it in the water (winch still hooked). With that wire disconnected it ran perfect. Let it idle, ran it up a few times in and out of gear. Ran pefect. I wanted to run it around a little bit but I was at a very unpopulated area of the river and by myself, so I kept it hooked up. I know this wire is part of the kill circuit. Is there any risk running this thing with that disconnected?
Engine Serial number: 0E114853
Any thoughts guys?