accelerator pump

[simpson]

1999 challenger 1800, twin 787

Hello everyone. Happy summer.

My starboard engine is "flat in the middle". Is idles ok, accelerates ok to 2.5k, hesitates, then jumps to 4k or more and runs ok. Above 4k it can run ok, but will fall off. I need to feather the throtle to maintain a steady rpm..

If I drop from high RPM to low RPM, the engine will stall.
When running at idle there is a low speed steering assist on this boat, where one engine will rev if the steering is turned to the stop. During low speed steering, the port engine jumps from 1.5k to 3k. During low speed steering, the starbord engine only jumps to 2.1k and is gagging.

Searches on this subject point to a accelerator pump problem. Is there anything else that could be wrong?

 

[kustomkarl]

Welcome to the seadoo forum simpson. Yes, it is the acceleration pump by the sounds of it. To check it pull off the plastic carburetor cover and remove the spark arrester assy. Now either look inside the throat of the carb, or use a mirror and locate a small brass tube pointing down. When you push the throttle forward, it will squirt fuel out the tube. it it doesn't it is blocked and you need to remove the carbs and with a compressor blow out the small valves to allow it to pass fuel. If you want you could join as a "premium member". As a premium member you can down load a authentic seadoo manual from the seadoo manual library. In the library is a variety of manuals for almost all years and models. You can view as many as you like on line as a PDF file, or download it and print it for your personal and privet use. There are operator manuals and repair manuals for you to do your own repairs on your seadoo. The repair manuals have everything from troubleshooting, repair procedures to winterizing. It contains wire diagrams torque specs and pictures for disassemble and assemble instructions. In the spec sheets it tells everything needed to maintain oil changes, spark plug gaps, carburetor rebuilds and impeller wear ring tolerances. Click on the "Seadoo Manuals" link at the top of the page for more details. If you need any help or get in a jam, we are always here to answer your questions too.

Karl

 

[simpson]

Started rebuilding the carbs last night. The non-pto side was very crusty inside.

Took the brass fitting for the high speed injector off of both carbs. I can not blow through it (by mouth), but carb cleaner did blow through it. Is there some sort of check or pressure valve in that little brass fitting?

Thanks for your reply.

 

[kustomkarl]

Yes, it has a valve in it to keep the fuel from backing up. If the spray goes through it it will work on the carb. You can not blow through it ...I use a compressor to clean mine and carb cleaner.

Karl

 

[simpson]

carbs + rave valves

Before i thoght about touching the carbs, I took out the rave valves and cleaned them. They were very, very dirty.

Rave Valves
About these rave valves... they had no springs under the caps. Is this possible? I'm thinking it's not. I'm thinking that the previous owner decided that the engine ran better without the springs, instead of cleaning the valves.

Once i got the carbs rebuilt and the engine started, the motors ran at the same rmp until 4k or so, then the one with the rebuilt carbs would need more gas to keep up with the port engine. So i took some rave valve springs from another seadoo and put them on the challenger. Once I did that, everything works as expected.

I broke one of the small rave valve bellows retention springs. Can I just replace this with a small zip tie, or will that ineterfere with valve?

Carb Rebuild
Back to the carbs. After i rebuilt the carbs (sbt kit), I couldn't get the engine started. Tried for an hour or so, but it got dark out. Got some quick start this morning and gave it a try. Didn't turn over. Removed the plugs, held a towel in front of the plug holes and turned it over. So much gas came out, it threw my arm back. I am talking about a lot of gas, it was like a washing machine. I did see that I left the throttle partially open overnight though (battery off).

I disconnected the gas input line the engine, cleared the engine, and got it started. Then hooked the gas line back up. Once I staightened out the rave valve issue, everything seems ok. (short 20 minute ride, several starts).

But let's say I flooded the hell out of the motor while trying to get it started. Shouldn't the non-combusted gas have been pushed through the rave valve and out the exaust? Is there a bigger problem here (besides me)?

Thanks for your help kustomkarl, I appreciate it.

 

[kustomkarl]

You can use a plastic tie for a temporary repair for the RAVE cover. Every time you hit the throttle it will pump fuel into the carb...via the acceleration pump. The fuel Will just sit in the bottom of the cylinders till it is either expelled through the spark plug hole or fired up and burned out the exhaust.
Letus know if we can help any more.

Karl

 

[seadoosnipe]

Rave...

I'm just now reading your post and from the very beginning, it seems your RAVE valves were to blame for this. I see you also found that there are suppose to be springs under the caps. The adjustment on those red caps should be either flush with the top of the black plastic cap or turned all the way down.

In their original configuration, they were down, then Seadoo came out with a supplement that said to adjust them flush. Mine, are all the way down. I seem to get better "hole" shot that way. As Karl has pointed out, the accelerator plug into the carb has a tiny small, ball type, check in it. One way and I found it impossible to blow through it. But like you, the carb cleaner seemed to work well.

Outside all the info that Karl has given you, check to make sure your accelerator pump is making up to the cam roller accordingly. It should be adjusted that as soon as your throttle begins to open, the roller contacts the cam.