What are the symptoms of sucking up weeds?

[soupdragon]

Hi all

It would be good to understand what the symptoms of sucking up weeds are?

Backstory. I bought the PWC (2000 GTI 717 3 seater) just recently and its been running fantastic. I was out on the lake a couple of days ago and was towing my son (17) in a tube (never more than 2/3 throttle, mostly half) and my daughter (12) as watcher and just like the previous day when towing both of them, ski was performing great.

We pulled in, switched my daughter into the tube and my son as the watcher. Off we went and it felt like I had lost a lot of power. A really struggle to get it on plane. The throttle response in general has been awesome up until then but it felt like I needed more throttle to get it up to any sort of speed and then, say for example I'm at 2/3 throttle with not enough revs, suddenly the revs would jump up without me changing the throttle position.

Overall, a feeling that the revs were far too low from what I would expect from being at a fairly high throttle position. There was also a lot of smoke from the exhaust while attempting and failing to get it on plane. I immediately abandoned the run and we pulled in and went to get some lunch.

I took it out for another try with just me on board and while I got similar symptoms for the 1st 30 seconds or so, it then went back to normal. I spent a few minutes testing. Slowly increasing the throttle and the ski responded exactly as expected. I then got my daughter on board to just go for a scoot around, and then swapped over to my son, went for another scoot around and the ski was back to normal. Didn't try tubing again though.

I did however notice towards the end that part of the lake near the jetty had weeds that were very close to the surface. It got me thinking that when my son (17) got out of the tube and my daughter took his place, and with me on the ski and my son riding at the back as watcher, with him being heavier and the fact that I'm going low speed over the weeds due to having to go slow to get the tension in the tow rope, the ski would be even deeper in the water due to his weight at the back.

I also remember earlier in the day at the slipway, a chap was getting his ski out and he was inspecting underneath at the intake grill. Maybe he had a similar problem. I certainly didn't notice these weeds before but we're in middle of summer and its not a lake I'm really familiar with.

Unfortunately I can't get to the ski until the weekend after next to do any testing/inspecting but I thought it would be good to get opinion if it seems like the weeds were the issue. I've read that the symptoms of weeds are that it revs high but doesn't really get going, whereas my issue is that its not revving high enough for the throttle position its in, and then all of a sudden, the revs jump up but ski doesn't really get going, coupled with a fair bit of exhaust smoke.

Its also weird that when I took it for a run with no towing, after the initial 30 seconds of similar behaviour, it went back to normal and stayed normal from that point on. Maybe its just not capable of towing a tube with 2 people on the ski as well and while it coped for some runs, its maybe not cut out for that type of load continuously?

 

[Spider4real]

Everything you described sounds like a weed issue.

Your ski can pull tubes all day long. As long as you got gas you can keep going.

The heavier the load the more you are likely to feel the impact of the weeds in the intake grate. Likely why it felt ok by yourself. Also as you ride some of the weeds may have cleared out on their own. Sometimes just putting it in reverse is enough to clear out some of the weeds.

When you say the the revs jump this is the classic symptom of cavitation caused by weeds (obstruction of the intake grate). The more weeds you got, the worse the symptoms. Eventually if you get too many weeds you will have cooling issues on top of the thrust issues.

In any case it takes 2 seconds and most can be removed in the water. Just reach underneath an pull out any weeds. Once you do everything will return to normal.

 

[soupdragon]

Everything you described sounds like a weed issue.

Your ski can pull tubes all day long. As long as you got gas you can keep going.

The heavier the load the more you are likely to feel the impact of the weeds in the intake grate. Likely why it felt ok by yourself. Also as you ride some of the weeds may have cleared out on their own. Sometimes just putting it in reverse is enough to clear out some of the weeds.

When you say the the revs jump this is the classic symptom of cavitation caused by weeds (obstruction of the intake grate). The more weeds you got, the worse the symptoms. Eventually if you get too many weeds you will have cooling issues on top of the thrust issues.

In any case it takes 2 seconds and most can be removed in the water. Just reach underneath an pull out any weeds. Once you do everything will return to normal.

Thanks for the detailed response. It'll be another 2 weekends before I'm back on the water but I'll do an inspection before I launch to make sure any weed remnants are removed.

I'm glad that these symptoms match weed symptoms. I've only just got the ski and being summer, I want to use it every weekend possible so it's comforting to know that it's likely weeds that are the issue.