GT-40 with no power(gutless)

[bchesley]

I am helping a buddy try and figure out why his 01 SAN with a gt-40 has no power on the bottom end. It has a slight miss at low RPM also.

We have replaced plugs, cap, rotor, and wires on the ignition side. We replaced the valve on the pickup at the tank. Replaced the low pressure fule pump because we thought it was a fuel delivery issue. I checked the PSI while running on the rail and it was around 36 PSI. Compression also checks out on all cylinders. I am at a total loss on why its gutless. It will only pull around 4000RPM at WOT also. I think that is just a sign of the weakness of the motor though. We have checked ground wires and power wires also.

Any ideas at all? After checking the usual suspects we are back at square one.

[Chexi]

RE: GT-40 with no power(gutless)

Brad, on the very unlikely chance that you did not already check this, have you checked the prop? Is this a drop in power from what he had before, or has it always been this way for him? Could be running the wrong prop, or perhaps have some prop damage.

[bchesley]

RE: GT-40 with no power(gutless)

This is a loss of previous power. The prop is fresh this year and we did check it for damage.

[east tx skier]

RE: GT-40 with no power(gutless)

Fuel filter??? A nasty flame arrestor can rob a little top end, but probably isn't the culprit at the bottom. Worth checking though and easy to see. How's the response from the throttle cable itself. I had one give me trouble on my last boat.

Any pop at the low end with hesitation? Did you get all of those plug boots pinched on the plugs? What about at the distributor?

Holiday Inn Express answer.

[east tx skier]

RE: GT-40 with no power(gutless)

Forgot to ask, does it have perfect pass?

[bchesley]

RE: GT-40 with no power(gutless)

Its got a brand new fuel filter and I did go back over the wires to see if one popped off but they are good. I have not checked the Flame Arrester though and will tomorrow. I cant imagine that it could cause this big of an issue. It doesn't have any popping or hesitation either. Its just is a little rough on the idle and a total dog getting on plane. It would not pull him up on a wakeboard with no ballast and just 4 people in the boat.

The cable itself is working fine and moving freely.

[eseybold]

I had the same problem for 2 years and just fixed it. I have a GT 40 2000 SNOB. I did everything that you did - to the T,,,and it still ran poorly.. So last week I started the engine at night time and looked carefully at all plugs .....a brand new plug was arcing to the engine block - the seal betwen the porcelain and the bolt was bad. It was impossible to see to the naked eye..I changed the one plug and I got my boat back to perfection after 2 years of trouble shooting.

Also - make sure your vacuum hose is not loose and also make sure the pick up tube in the gas tank does not have crud around the screen - these are 2 very common problems also

[Bobby]

make absolutely sure that you have the wires in the right firing order

[jjgag60]

No power

On the Gt-40, we have four sensors, on the fuel side for EFI-. TPS, MAP, MAF, and Idle When I could not get mine to idle, i thought it was the TPS (throttle position sensor) I was told that should not affect, the iddle , but if you accelerate and it wont power up, the sensor could be bad.

So download the repair manual and check the sensor. The TPS might not be getting the correct info to the computer to advance the gas and spark. Good luck.

I am just learning about the MAF and how important it is to idle speed. Check yours it might just need cleaning.

All the sensors can be ordered at NAPA. They are expensive so it helps to know someone who can get you a discount.

[bchesley]

RE: No power

Well I got the boat running good but not sure what actually fixed it. We did so many things to it before we ran it in the lake I cant say for sure what it was, but my buddy has permagrin after we ran it. Thanks for all your suggestions.