04 Sportster 4tec stalls when throttle chopped

[Marco1]

This has been driving me nuts since I bought the boat last spring. Every time I chop the throttle the boat dies.MAYBE if i slow it down VERY gradually it will stay alive but mostly no. This is pretty annoying and fairly embarrasing when i come to slow down to load and end up bonking into my trailer sideways lol.

Symptoms: Stalls when throttle is killed all the way.
Will not start for approx 2or3 mins then starts fine
sometimes there is a slight surging of throttle at 2500-3500(rarely)
usually worse when warm
no dummy light on
dealer has had it 3 times and cannot duplicate the problem
brand new plugs
beautiful full tank premium
battery posts mint and battery full charged
This is all computer system,I have no carbs ot fuel filters etc etc. what else can i look for? Ive tried experimenting all over the lake but everytime I throttle up cruise and then kill it,she dies.I cant see much on other threads,thanks for any advice.Brett

 

[jcrango]

I have the same problem with the same boat. I had to take the shifter and throttles apart and remove the locking pins so I could shift to N without pulling the throttles all the way back. It started on my left engine and now on both. I am starting to wonder if it has anything to do with the holes in my air boxes. I knew I had a hole in the left air box and then when the right air box developed a hole I think that engine started doing it. There are some electrical components in the air boxes. The air boxes were part of a recall but the previous owner didn't address it and I have only had the boat for 4 weeks. If a piece of the air box gets stuck in the throttle body the throttle will stick open. It happend to me. Hope we can solve this is sure is embarrassing.

 

[Marco1]

hmmm i never thought about the airbox.Ill check that out. I havent much found out via google so I seem to keep experimenting on my own. One thing the dealer did try (of which was my idea) was to actually adjust the throttle cable so when it is fully chopped back its still like 5% throttle or something. Seemed to work for a bit then same thing.Ill post any solutions. so far I have been throtteling down like WAY far away so i know it will stay runniing then creepin into the launch.

Anyone else heard of this? What is in the airbox that could cause me grief?cheers

 

[Dr Honda]

The fuel injected boats are hard to diagnose problems with.

If it was my boat... I would be looking at the TPS, or MAP sensors. Unfortunately, you need a dealers computer to watch their functions as the engine is running.

 

[jcrango]

Rather than mess with the throttle cables you could adjust the throttle stops on the throttle linkage. Each screw has a black plastic cap on the end. Pop of the caps and you have a slotted head of the screw that is the throttle stop. This may make more of a consistant return point than the cable.

 

[jcrango]

My hope is that the holes in the bottom of the air boxes alows combustion air to get into the engine without passing through the top of the air box where the electrical components are and therefore confusing the computer when the throttles are cut back. That is the only thing left I can think of. Please let me know how you make out with yours.

 

[jcrango]

Stalling fixed

My engines stalling after chopping the throttles has stopped on my last 3 outings. Not sure what did it can only tell you what I did. After doing the following no more stalling. Changed spark plugs old ones looked in fine condition but I read looks mean nothing. Went throught ALL electrical conections. Found no corrosion but did find the battery conections a little loose (previous own put in a new battery and didn't tighten wing nuts very good), all fuses were good. In the past both volt meter warning lights would flicker on occasion. This has now stopped. I did not repair the air boxes, they both still have holes on the bottom halfs. Not sure what did the trick but it sure is nice not to stall all the time.

 

[Marco1]

I actually did do some fudging around with the loose and coroded battery one day(after floatin for a bit then didnt start!) seeed to be better for while like usual then back to its grumpy sef.Im still up at work so I haven had a chance to play with it. Ill post solutions if I find.

 

[Marco1]

so usually Boat starts after a few minutes........nope not last night.it slept at the marina after paddling back in the dark lol.this is annoying i love this little boat i dont want to sell it just for a dumb problem.

 

[jjbauer81]

I'm having the same problem with my 2004 sportster LE DI. It starts fine, runs fine, but as soon as I back off on the throttle it dies. Usually starts up again, but is very difficult to get started again. Let me know if you figure out what it is!

 

[Marco1]

I changed out new plugs. better but not for long haha. I dumped a bunch of injector cleaner in there-maybe there poopy. Im going to order a tps and see what that does.kinda makes sense. Im not going to adjust anything mechanical because when it is idling it idles mint. its just the quick cutting back of throttle that sewers it.Ill figure it out! arg! Whoever posted about figuring out problems with injected engines is right.

 

[Marco1]

I changed out new plugs. better but not for long haha. I dumped a bunch of injector cleaner in there-maybe there poopy. Im going to order a tps and see what that does.kinda makes sense. Im not going to adjust anything mechanical because when it is idling it idles mint. its just the quick cutting back of throttle that sewers it.Ill figure it out! arg! Whoever posted about figuring out problems with injected engines is right.

 

[evanviegen]

Same Problem here. I was wierd. Happened in the middle of last summer at the cottage. Found it weird b/c it was first just one engine then the next time it happened it was both engines on the Speedster 200 I have. What is the only link between both engines... Fuel and Battery I think? Each engine would have their own TPS and MAS, I would think? So I grabbed my buddies battery off his boat and tried it out. Ran perfect! So had the battery load tested and it tested fine, but when he tested the ring terminal instead of the post (which is where I connect them, voila, battery tested bad. Bought a new battery and it ran great the rest of the summer. Here is the weird thing. I left it for about 2 months before winterizing it, and I just barely got it started. It ran fine while I was running some Fuel stabilizer through it, but right at the end, as I brought it back to the dock, it started doing it again. Crap!! I think maybe not enough charge going through? I am going to charge up the battery over this winter. I did all new spark plugs in the fall, so I will repost if I have any further problems.

It is definitely electrical and the odds of having the same problem on both engines at the exact same time... well it has to be in the main circuit running off the battery I think...

Let me know if anyone has some definitive answers.

 

[RFoster130]

I can believe that. The fuel injected motors are very touchy when it comes to battery/charging issues. Without the proper juice, they run weird.