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135 Optimax will not idle

T

tom_c

Member
"I have a 2000 135 optimax tha

"I have a 2000 135 optimax that sat for 14 months. I cleaned the gas tank, put new fuel in it. Replaced the fuel line to the engine. Cleaned the varnish out of the vacum operated fuel pump. Replaced the low pressure electric fuel pump. Tested the high pressue fuel pump. Cleaned, inspected the first and second stage injectors. The engine runs fine above 1300 rpms. When it drops below 1200 rpms the engine shuts off. Does anyone have any more ideas?"
 
"Tom, if you have checked all

"Tom, if you have checked all the igniton/electrical connections (common cause of problem on direct injected engines) then you may want to have the TPS (Throttle Position Sensor) checked.

If it is starting to go it can cause irratic operation at either high or low speed operation. If it goes all together, the engine won't start/run at all..."
 
"Thanks Graham, I new I would

"Thanks Graham, I new I would get an answer from you. I also have heard that if the air compressor is not building up enough pressure that it might not run at idle speed."
 
"Yes, that is also true. The

"Yes, that is also true. The Mercs (and Tohatsu's) use considerably less pressure than the Evinrudes and Yamaha's - but still need about (max) 80 psi of air pressure from the pump (compresser) to operate properly.

The fuel is injected at (max) 90 psi (give or take a pound).

For the mix to be correct, the motor must maintain that 10 psi difference between air and fuel.

This is accomplished by a "tracker valve" which is a diaphram controlled by a 10 pound spring (located in the starboard fuel/air rail).

If the pressure on the fuel side is 80 pounds, the pressure on the air side should be 70 pounds (+ 10 pounds of spring) so that both sides are equal. As the pressure "spikes" momentarily when the engine calls for more/less fuel, this valve should keep the pressure balanced.

So it is possible that this could also be the cause of your trouble. A worn spring, jiggered diaphram could cause an imbalance creating a lean or rich condition..."
 
"Sorry, bad math - 90 pounds o

"Sorry, bad math - 90 pounds on fuel side - 80 on the air side, plus the 10 pound spring (so 90 on each side) not 80, like I typed above
"
 
"I will know in a couple of da

"I will know in a couple of days. I am taking it in for the dealer to put the ddt on it. Then I will do the repairs it needs. I was also informed by the dealer that I should have recieved a notificaton of a recall on the injectors, which I did not get. I will keep this post updated so as to what I find.
Tom"
 
"I have a 2006 model 135hp opt

"I have a 2006 model 135hp optimax.

It is currently idling very rough and up to about 1500rpm it seems to be missing.

It has recently been serviced, new filters, plugs, gear oil etc..

I have been told that it could be the FUEL TRACKER VALVE, although there are no error codes displaying on the smart craft gauges??

Does anyone think it would be anything else that could be the problem??

Is this a common problem with these engines?

If anyone can give me some info that would be greatly appreciated!!

Thanks"
 
"Brent, I am going to say that

"Brent, I am going to say that you got a bad spark plug when they installed the new ones or you have an injector not firing properly or possibly water in the fuel. My 135 is 7 years old and the only problem it ever has is plugs fouling. If you read the above post about my engine - we found the problem was bad spark plugs. This has happened 2 times. I figure I get about 60 hours out of a set of plugs."
 
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