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RSRBOB, Technician
Category: Boat
Satisfied Customers: 1078
Experience:  Former Yamaha Factory Service Rep, Dlr Line Tech, Serv Mgr, G/M
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Have a 94 waverunner gp3 701cc runs great but on problem.

Customer Question

Hi I'm Gre , Have a 94 waverunner gp3 701cc runs great but on problem. When running at 3/4 to full out engine all of a sudden shuts down but can be re started right away. Problem happens over and over.
Submitted: 1 year ago.
Category: Boat
Expert:  RSRBOB replied 1 year ago.

Hi and thank you for your question.

The first thing we need to do is to check the compression. We need to be 100% sure the engine is mechanically sound before we proceed into the 2 other possible areas, fuel supply or electrical.

When you do the compression test, you want to leave one spark plug in while testing the other cylinder. Hold the throttle wide open and crank the engine until the needle on the gauge quits climbing.

Let me know what you get.



Customer: replied 1 year ago.
Will get a tester and check that tomorrow and get back to you
Expert:  RSRBOB replied 1 year ago.

Super, just post your test results here and then we can decide what is the best course of action from there.



Customer: replied 1 year ago.
Hey man Compression checked Both cyl read 140 did it twice to make sure. The plugs look good also.
Customer: replied 1 year ago.
Both cranked at 140 and did it twice make sure and the plugs looked really clean.
Expert:  RSRBOB replied 1 year ago.

Super, thank you for the additional information.

Since we seem to be solid mechanically in the engine, the next area to check would be the carburetion. It sounds like there is a problem with the high speed circuit in the carb. I think you have the WRIII GP with the 701cc single carb engine. If so, it makes the job very easy. You will need to take the carb off and take it apart and inspect the internals. The main thing I would be looking for is where the high speed screw is set right now and if there is some debris in the high speed jet.

Here is a diagram of the carb:

The high speed screw is reference #13. You have a high speed screw and a low speed screw. The high speed screw is the one that is NOT on the same side as the throttle cable. It is also physically higher up on the carb than the low speed screw. I want you to take the carb off first, then look at that screw and count how many turns it takes for you to turn it in until it is lightly seated (stops turning freely). Don't force it. When it stops, you stop. Let me know how many turns it was out.

Next, you need to take the steel plate (#31) off the carb and the diaphragm (#30) to get to the jets. You will also have to remove the "Body 1" to get to the jets. If you have an impact driver with a #2 phillips bit, I would suggest using that to break those 2 screws loose that hold Body 1 to the main carb body. They are usually very tight, especially if they have not been out in a very long time. Once you get Body 1 off, the 2 jets, high speed and low speed, are screwed into the main carb body underneath it. The high speed jet has a much larger orifice than the slow speed jet. #16 is the high speed jet. You will notice it is about in line with the high speed screw too. Take that out, being careful to not strip the screwdriver slot. Make sure you use a lot of down force into the jet on your screw driver so it doesn't slip. If you damage the slot and round it off, you are going to have a really hard time getting the jet out. Since it is idling fine, I would not even bother with any of the slow speed stuff.

While you have the diaphragm off, check to make sure they are no perforations in it too. Also, there is a small clear strip of mylar on the backside of Body 1. Take a look at it and make sure it is laying flat against the Body 1 as well. You can remove the high speed screw now and blow through the passage with contact cleaner and compressed air to make sure it is not restricted. If everything seems to be in order on this side of the carb, we will need to jump over to the other side to inspect the fuel pump assembly.

Again, use an impact driver to remove the 4 screws at the corners of the fuel pump. These screws are tight and tend to get stuck when they have been installed for a long time. Take the outer aluminum piece off the carb. The clear mylar diaphragm will probably stay stuck to the paper gasket which stays stuck to the outer cover. That is ok. Just take a very close look at it and make sure there are no perforations in it. Look very closely, you don't want to miss one. Also, notice is there is water between the mylar and the aluminum. Hopefully not, but check just in case.

Once you check that out, pull the aluminum block out, Body 2 (#39) and inspect the 2 small round mylar check valves that are installed on the block, on opposite sides. Mainly what you are looking for on these is a ripple or crease in the outer edge that would prevent them from sealing completely. Normally they lay perfectly flat against the body 2, but when damaged, they get that crease in them and no longer seal all the way around. If it is not perfectly flat, it will need to be replaced.

Check all that out and let me know what you find.



Customer: replied 1 year ago.
Hey man got the carb back together and put in and ski runs great thanks for all the help. Sorry it took so long to get back to you been in and out of town the last couple of weeks. If I run into something else I will look you up thanks again.
Expert:  RSRBOB replied 1 year ago.

No problem on the delay. That is great news, so glad to hear it. Love the success stories. :)

If I have answered all your questions, please click on the green accept button and leave positive feedback. If you need more help feel free to ask.



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