Boat idles fine then loses water flow with increase in rpms

[N8ID]

I have a 2003 Sportster 4tec. It has always ran great, no problems! I started it up and idled okay and then when I gave it throttle the engine reved up but no power to the pump. Then the engine died. Start it up And idle everything is fine. Water coming out the pump. And moving along fine.
I got the boat out started it and it seemed fine. Not an engine problem
anybody point me in the right direction on this?

 

[POPPS]

Check for rope or obstruction in the pump.

 

[N8ID]

Yep!! First thing I did. I thought maybe something was obstructing the flow.
I have heard on skis that the drive shaft can get out of alignment. Causing similar type of problems.
Thanks for the answer !

 

[POPPS]

It is highly unlikely that the drive shaft suddenly is out of alignment..,your description of your symptoms are a bit fuzzy,,.if you give it throttle,,,does the motor respond,,,but,does not advance,,,just cavitates,,,or does the motor not respond to the throttle.?is it supercharged?,,,if yes,,,check it out,,,,

 

[N8ID]

Thank you for responding! The engine responds and takes off. Once that happens it appears that it looses water coming out the pump. The then then dies.
It starts up and idles fine. I can limp along but when I give it throttle the same theming happens. I hesitate to say it cavitates, because that word is used to describe quite a few things on here. But yes it cavitates.
Once I got it out of the water I started it and the engine ran great. I didn’t feel any vibration. I checked the pump and intake grate, nothing there. Impeller blades are fine too.
it is not super charged. Just the 155 4 tec engine. I put a new pump, impeller, and wear ring in it over the winter and the boat gets quite a bit of use. Has been running great,
Thank you for your help

 

[POPPS]

When you hit the throttle...does the motor respond and rev?

 

[N8ID]

When you hit the throttle...does the motor respond and rev?

 

[N8ID]

Yes

 

[POPPS]

I would pull the pump,,,and start from scatch,,,you made an error somewhere,,,did you install the pump deal correctly,,,did one of the "O" rings fall of the transom,,,,one on the left is for cooling,,,!!.,

 

[N8ID]

I’ll check it out. It’s not hard to pull the pump. I would have thought it would have shown up before now. I have put on over 20 hours this summer.
but like you said gotta start somewhere!
I’ll let you know what happens!
Thank you for your help!

 

[Joe Starbuck]

20 hours is enough time to pick up some rocks, shells, garbage and gouge your wear ring. Less likely is your shaft seal is leaking air under power.

 

[wayneh]

Does your boat have fuel shut-off valves? My boat behaved similarly when I forgot to open the valves (I have a twin engine boat). The valves leak enough for the motor to start and run at idle but the motor dies if the throttle is advanced.

 

[MacSeaDoo]

The fact that the engine is dying points to an issue with your engine.

The only thing the engine needs from the pump is a water flow to cool the exhaust.

If there was not enough flow you would get a high temp alarm.

I would guess you have an engine problem. Start with the plugs first, pull then as they often will tell you alot about what is going on.

 

[N8ID]

The fact that the engine is dying points to an issue with your engine.

The only thing the engine needs from the pump is a water flow to cool the exhaust.

If there was not enough flow you would get a high temp alarm.

I would guess you have an engine problem. Start with the plugs first, pull then as they often will tell you alot about what is going on.

 

[N8ID]

That’s a good idea! I didn’t get a chance to do anything on it last weekend. I should be able to spend so time checking it out this weekend.
Thanks for the advice.

 

[MacSeaDoo]

One thing to add.

I helped put a friend yesterday with his rxp 260. He mentioned symptoms simular to yours. The machine was in limp home mode.

Put Candoo on it and it had a crap ton of codes. Most were ibr related with loss of communication and other related codes.

The code that was the most important was the low voltage code. It measured 9.7V.

Checked the battery and sure enough the positive terminal was really loose.

Tightened it up, cleared the codes. Back in business.

I was actually surprised by the seat feel of limp home mode. When I was bringing it to the trailer, I was sure I was going to see a completely trashed pump. The pump was perfect.

Just another suggestion.

BTW, Candoo is worth its cost in times like this and I was happy to be able to help a friend. (I am now at my 4 license limit though)

 

[N8ID]

I never thought about limp mode! I guess I haven’t had it happen. I bought a CanDoo, just need to set it up! I am going to have a busy weekend! I can’t wait!

 

[N8ID]

Sorry I haven’t gotten back. I checked things over and couldn’t see anything wrong. Started it up and ran great.
so I put it in the water waiting for the problems to start.
they never did. Ran the boat for half hour and not one issue.
I guess it healed itself sitting in the driveway…….

 

[Joe Starbuck]

Sorry I haven’t gotten back. I checked things over and couldn’t see anything wrong. Started it up and ran great.
so I put it in the water waiting for the problems to start.
they never did. Ran the boat for half hour and not one issue.
I guess it healed itself sitting in the driveway…….

I’ve seen seaweed dry out and disintegrate sitting in my driveway.