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Yamaha 1989 130hp

F

Faema

New member
Hi there.
This motor is driving me crazy!
Heres the fault: After running for 10mins, if we drop to idle for 10 seconds then pin it. The motor accelerates onto the plane fine and up to desired speed. After about 15 seconds. The motor drops by about 2000rpm for about 10 seconds. Then motor returns to correct and stable running rpm
This makes watersports very difficult..

Here's what I have done so far:
Carbs rebuilt, float levels correct.
New fuel filter.
New fuel pump.
New coils.
New plugs.
Replaced failed fuel hose.(collapsed lining)
Borrowed a good CDI unit. ( No improvement)

Fuel bulb goes hard
Temperature audible alarm works. Fault still occurs with thermocouples out of block.
Oil level audible alarm works
Battery good
Good water telltale.
Checked thermostat function in boiling water.

Cdi unit is CU2481.

Any suggestions are appreciated.
 
You are hanging a float needle valve in one or more carbs. Put the boat in the water, pull the cover off the carbs, have someone drive the boat and when the cylinder-s drop, look in the carbs you will see which one stops pulling fuel through the emulsion tube.

You can also put your finger over each tube when the issue happens to find the cylinder-s.
 
Docksidemarineservices said:
You are hanging a float needle valve in one or more carbs. Put the boat in the water, pull the cover off the carbs, have someone drive the boat and when the cylinder-s drop, look in the carbs you will see which one stops pulling fuel through the emulsion tube.

You can also put your finger over each tube when the issue happens to find the cylinder-s.
Click to expand...

Brilliant! I will try this over the Xmas holidays. Thanks Chris.
 
Hi Chris.
Thank you so much for the advice.
I found the gasket had pulled in just enough to just catch the tip of one float.
So a newly fitted gasket has done the trick.
It is quite comical how I chased myself from one fault and into another!

Cheers!

Paul S.

Docksidemarineservices said:
You are hanging a float needle valve in one or more carbs. Put the boat in the water, pull the cover off the

carbs, have someone drive the boat and when the cylinder-s drop, look in the carbs you will see which one stops pulling fuel through the emulsion tube.

You can also put your finger over each tube when the issue happens to find the cylinder-s.
Click to expand...
 
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