starboard engine bogging @ 3500 rpm

[m.colley]

Need some help/advice. I took the Sportster 1800 last weekend after solving the starter issue and she ran good for a solid hour. Today we took her out again, I pre-started her in the driveway with no issues. At the lake she started right up but seemed to be running just a little rough on the starboard engine, after clearing the "no wake" zone I eased into the throttle and she ran okay until she hit 3000 rpm or so, at 3500 she bogged and the starboard engine died. I finally got it restarted and eased it back to the dock. This whole time the port engine ran great.
After pulling back to the dock and off loading some people and gear I eased her back out and got her back out of the no-wake zone. After running below 3500 for several minutes I eased into the throttle and she climbed on passed 3500 for a couple of minutes then dropped back down again. I got it up above 3500 several times and for several minutes once for as long as 5 to 10 minutes she cruised like she did the weekend before...

Sounds to me its a fuel/carb issue but as always I'm looking for suggestions and advice from those with more experience.



Martin

 

[Dr Honda]

Don't continue to run a 2-stroke engine that is running poorly. You can kill the engine.

It sounds like a fuel supply issue. Either you have an air leak in the feed hoses... or the carbs, or the fuel select valve is plugged up.

 

[m.colley]

Hey Doc, am I missing something or just overlooking the fuel selector valve? Doesn't seem to be a switch of any kind anywhere near the drivers seat or anywhere else that I can find?

 

[m.colley]

is the fuel select valve located on the hull under the throttle assembly like it is on other models that have the fuel selector switch?

Martin

 

[Dr Honda]

Yes... on the 1800.... it should be by the driver's right leg. (when sitting at the helm)

 

[m.colley]

Yes... on the 1800.... it should be by the driver's right leg. (when sitting at the helm)

Am I seeing things Doc or does the fuel pump replace the fuel valve on the 1998 Sportster 1800 and the Challenger 1800. I've looked at the parts cut sheet/microfiche on three different sites including our sponsor parts site here and even went to my service manual and unless I'm seriously overlooking something they changed something. Heck I even went and pulled the throttle/directional assembly and there is no fuel valve where it is on the regular Challenger & Sportster..

Is there a way to trouble shoot fuel hoses, fuel pump, etc to determine which is the culprit with out throwing parts at this thing?

Inquiring minds want to know...

Martin

 

[CaptSteve]

I don't have the manual for the 1998 Sportster 1800, but according the parts manual the 1999 Sportster 1800 there is no fuel selector valve.

A couple of things I would check;

1. Do a compression check on the engine. I should read ~150psi on both cylinders within a few psi of each other. Also check the spark plugs for a lean or rich condition. Check and clean your Rave valves. A stuck closed rave can also impact mid RPM performance.
2. If you have the gray tempo fuel lines, replace them now. If you have the gray lines, you will also need to clean the carbs, replace the filters in the carbs and make sure all the jets, seats, passages, etc are not blocked. The Gray lines deteriorate from the alcohol in the fuel and create a gooey substance that clogs everything.
3. If the fuel lines have already been replaced, then you need to check that the lines are not clogged, pinched, or loose. You can remove the lines and blow compressed air through them to check. Also make sure they are not sucking air.
4. Pressurize the fuel system and make sure there are no leaks. Try swapping fuel pumps and see if problem follows the pump.
5. There are filters in-line between the pump and the tank. I would suggest taking them out and cleaning or replacing them.
6. There are filters in the carbs. Take them out and make sure they are not clogged. Check the Jets, needle valves, and seats and make sure they are clean.
7. Check the pop-off pressure of the carb. A too high pressure can affect fuel delivery.
8. Check the throttle cable adjustment. Make sure at full throttle that the butterfly's are opening fully.
9. Check the cooling system regulator valve. Make sure it is not leaking or stuck.
10. Check your rotary valve timing.

This should keep you busy for an afternoon or so.

 

[howie099]

No fuel selector on the dual 717's in the Sportster 1800's. The only place I have seen they gray lines on Sportster 1800's is on the fuel pulse lines. CaptSteve covered the rest of the stuff to check.

 

[m.colley]

thanks Steve and Howie, time to do some research and investigate..

Martin

 

[Dr Honda]

Am I seeing things Doc or does the fuel pump replace the fuel valve on the 1998 Sportster 1800 and the Challenger 1800.

Martin

Sorry I was gone... my computer died yesterday.


OK.......... wellllllll. No. a 1998 1800 doesn't have valves... but the 97 does. AND... you signature says you have a '97 1800. You may want to fix that.

 

[Dr Honda]

The quick and easy way to check things, is to remove the pump, and then try to draw fuel up the hose. If you can, then check the pump. You can do that simply by pulsing the "Pulse" hose. (suck/blow) it should cause a draw on the intake side of the pump. Or... take the pump apart, and just clean/check all the internal parts.

 

[m.colley]

Sorry I was gone... my computer died yesterday.


OK.......... wellllllll. No. a 1998 1800 doesn't have valves... but the 97 does. AND... you signature says you have a '97 1800. You may want to fix that.

Sorry to hear about your computer Doc. Your right my profile does say I've got a 1997 and that's the way its registered but I'm led to believe its actually a 1998, based on things like the fuel valve etc etc, sorry for the confusion. Thanks also for the tips on how to check the pump, pulse lines etc. I'm gonna go over the fuel system starting at the tank and see what I find..

Thanks again everyone

Martin