Turbojet

[Surge]

I have a 1995 Four winns fling with a 115 turbojet. I have a bit of a problem and was wondering if any of you can help.

The situation is that once the engine warms up it starts to make a popping sound. Not really like a bang or anything that would really scar you but i still think it inst normal. The popping sound is relatively fast and it will only happen at a specific point in the throttle. that is pretty much mid-rpm's. It it still sounds unclear please let me know so i can describe it a bit better.

In an effort to stop it i used sea foam in the fuel system. and i have added new spark plugs. hope that helps.

I am also wondering if any of you know were i can get a new engine alarm for the boat. Mine just went out and i cant find a place to order one.

Thanks in advance.

 

[ezeke]

Re: Turbojet

I rebuilt the engine for a 94 fling that I gave my nephew for graduation. The engine is a basic V4 115 crossflow with some inboard components to keep from blowing up the boat. The mechanics on this forum are really good on the V4 OMC crossflow, so they should be able to help.

The parts diagrams for the whole system, including the jet drive are on the BRP web site:

http://epc.brp.com/default.aspx?brands=ej&lang=e

The Four Winns site has a download for the electronics.

 

[ezeke]

Re: Turbojet

Do you think that the sound may be coming back through the carburetors, out through the exhaust, or is it mechanical?

 

[Surge]

Re: Turbojet

my guess would be that its coming from the carbs, i dont think it is mechanical because other than that the engine runs fine.

 

[tashasdaddy]

Re: Turbojet

reed valves.

 

[Surge]

Re: Turbojet

can you please clarify the reed valves im unsure. Do you know how they may have malfunctioned or why it does this? Any way how can i test for sure. How hard would they be to replace.

Thanks

 

[ezeke]

Re: Turbojet

The reeds are in the intake manifolds in 4 clusters - 1 for each cylinder. Take a look at the intake manifold diagram on the BRP parts catalog site. The reeds are lifted by the vacuum created by the upward movement of the pistons and closed as it moves downward. The vacuum pulls the fuel through the carburetors and the reeds prevent the fuel and exhaust gases from running back into the carburetors. The action of the #4 piston also creates the pulse that drives the fuel pump.

The pulse limiter fitting valve may be involved with your problem. It should be checked. It is installed on the port side of the intake manifold and has a hose leading to the fuel pump. It has a check valve in it that, if malfunctioning, can allow fuel to be drawn into the engine, or can cause the fuel pump to limit the supply of fuel. Either circumstance can seriously damage the engine.

 

[Surge]

Re: Turbojet

Hi sorry i couldn't get back here sooner but i was looking for the parts diagram but i cannot see anything under the intake manifold section, or any other section for that matter.

After looking at the engine i was wondering if This Was it.

http://i137.photobucket.com/albums/q202/Surgeevg/pulse2.jpg
here is a photo of how it goes zoomed out.
http://i137.photobucket.com/albums/q202/Surgeevg/100_1443.jpg

Am i warm or cold.

If I'm very off can you please help me because i that is the only fitting that went to the intake manifold from the VRO pump. Thanks in advance

 

[ezeke]

Re: Turbojet

Sorry for using someone elses terms, the "reed" is called a leaf in OMC parlance and that was my primary reason for the reference.​

The other concern was with the pulse limiter valve that powers the fuel pump. and the gold and blue fiitting in your photo appears to be it. It should connect by hose to the intake manifold, and to the fuel pump by hose at the other end.​

It is part # 435010. It can be cleaned with carburetor cleaner, but if there is a lot of carbon in it, you need to take other action. It is not a true check valve but closes under high pressure rather than always preventing flow.​

If the pulse limiter fails, high pressure will reach the fuel pump and may rupture the diaphram, which may allow fuel to be sucked directly into the engine, and which will prevent the proper functioning of the pump.​

 

[Surge]

Re: Turbojet

would you suggest i clean it, or how can i verify if it is working or not. Can you blow into it and see if air goes through, or how can i tell. Thank you soo much for your help by th way.

 

[Surge]

Re: Turbojet

Anyone know how? ^

 

[ezeke]

Re: Turbojet

Periodically the pulse limiter needs to be removed and cleaned with carburetor cleaner. If it is heavily clogged with carbon, other problems are indicated by the condition.​

 

[Surge]

Re: Turbojet

well i just took it off and i strayed it with carb cleaner. I also blasted it with compressed air. It did close but it took 30 psi to do it. Is it a little high or am i just way off on the testing procedure.

 

[ezeke]

Re: Turbojet

Sounds about right. Was it clogged?​

 

[Surge]

Re: Turbojet

no not really. So if its fine then now should i look into the leaf (REED) valves?

 

[ezeke]

Re: Turbojet

That was someone else - I would think that if the reeds were bad the engine would cough back through the carbs and you would notice the lack of performance.​

I was following the service manual. It said to check the pulse limiter and....?Note, If you find excessive carbon deposits, check the engine for cause of backfiring:
Linkage adjustments incorrect;
Engine Temperature Incorrect;
Crankcase air leaks;
Carburetor problems;
Extended use of flushing attachments.?
Service manual - Page 2-15.


You might want to check for piston slap. Also, get a screw-in compression guage and check the compression on each cylinder. The compression of each cylinder should be within 10% of the others.
​

​

 

[Surge]

Re: Turbojet

ill test the compression and i will post here. But should i test it with the engine running, or just crank it and read the gauge. (Not let it start)

 

[ezeke]

Re: Turbojet

Compression test:

ignition off so there will be no spark,
all spark plugs removed,
not required but engine should be warm if possible,
make sure that the threaded guage fitting is no longer than the spark plugs,
be consistent in the amount of time you crank for each cylinder.

The cylinders are numbered top to bottom with the top right cylinder being number 1.

Write your readings down so that you can refer to them.
​

 

[Surge]

Re: Turbojet

Thank you so much ill take those readings asap

 

[lexkyboater]

Re: Turbojet

One thing you can do to test the reed valves without taking it apart is run it and put a business card in front of the carbs. If there's a little mist of gas on the card, that's normal. If there's a lot of gas on the card, the reeds are not sealing and either need to be replaced, have something in front of them that's not letting them close down against the reed box all the way on the piston down stroke, or the gap is wrong. At rest, I believe I read they should be .010 away from the box. They open to let gas in, and will close all the way on the piston down stroke, even with this gap.