Why can not my Chrysler 105HP hold high speed?

[liusigou]

It will slow down automatic a few minutes after I give full gas

 

[DeepCMark58A]

Fuel delivery, start by checking the fuel filters.

 

[liusigou]

But 80% gas is fine.

 

[Fleetwin]

IS your fuel tank VENT open and unrestricted?

 

[liusigou]

I am not sure .How can I check it.?

 

[DeepCMark58A]

But 80% gas is fine.

It is getting enough fuel to operate at 80% not enough to operate at 100%

 

[liusigou]

Sorry. Maybe you misundstood me. My boat can run very fast if I gives it with full gas. But a few minutes later it will slow down automaticly. that is the issue.

 

[Fleetwin]

Is the fuel tank vent FULLY open? Clear of obstruction? Has no kinks?

 

[liusigou]

Could you tell me where the fuel tank vent is located please?

 

[DeepCMark58A]

Top of the gas can either on top of the cap you remove to fill with gas, or on the top most part of the tank. It should be a round screw that is groved so your fingers can grip turn it counter clockwise. Or is the actual throttle arm moving off of full throttle?

 

[Frank Acampora]

I am not sure I understand. Is the engine slowing to about 3/4 throttle with no fuel problem? Or, is it running out of fuel at full throttle? If it is running out of fuel, it will almost stall. If there is no fuel problem, the control handle is backing off. Most do not have a tension adjustment and you need to keep your hand on the handle.at full throttle.

 

[liusigou]

Thank Frank for your replying. When it slow down the control handle is still in the full throttle position. thank you

 

[Frank Acampora]

It slows at full throttle. If you back off on the control handle for a couple of minutes and then give full throttle, if it runs fast again for a minute then slows. You either have a partial clog in the fuel lines or quick-connect fittings OR the fuel pump is old and can not keep up with the full throttle fuel demand.

Buy a new fuel pump diaphragm and gasket and replace them. No one will offer one listed for your engine but any part listed for an early Force 85, 120, or 125 will be the same.

 

[DeepCMark58A]

Geez sure sounds like a fuel delivery issue see post #2 on this topic.

 

[liusigou]

Can anybody help me to solve this issue that my boat can not hold the high speed?. I always slow down automaticly after I give it full gas. I have checked the fuel tank vent . It is always open that a big pipe connect to gas tank without the tank cap. and I know where the gas filtering and gas pump. Need I buy a one. Used one? there is link for the fuel pump in ebay.

http://www.ebay.com/itm/USED-CHRYSL...ash=item41a106c56d:g:Ca4AAOSwf-VWYGJ9&vxp=mtr

 

[flyingscott]

Very simple test when it is running and it starts to lose power pump the primer if the motor starts to run normal the fuel pump is the problem. If the vent is the problem the ball should start to flatten out or look like it's trying to be sucked in on itself.