50 hp Bigfoot 2003 runs rough when warm.

I have a 2003 50 hp bigfoot that will run great when you first start it, but once it warms up it will not run. It will spudder and run very rough. At full throttle it will barely idle. Once it cools down again it will run great. I have replaced the following parts:

1: Low pressure fuel pump
2: fuel line with bulb.
3: check valve for fuel line
4: fuel quick disconnect
5: low pressure fuel filter
6: High pressure fuel filter

I need help.

Thanks

Scott

Re: 50 hp Bigfoot 2003 runs rough when warm.

perhaps better to look things over before buying more parts.
what is the compression cold vs warm?
not really familiar with 2003 (mostly older ones fer me) is it carbed or injected? It sounds to me as though your air fuel mixture is off.... thinking rich (would have to hear it run) running cool would do fine rich, as it warmed up it would begin to drown out if fuel mixture remained the same.
easy check in my book would be to squirt or spray a bit of fuel/oil mixture into carb/throttle body when warm and see if it fires, if so fuel delivery issue and you at least have it narrowed down.
if carbed and there is a mixture adjustment for low speed i would likely try adjusting this.
do you still have spark once it warms up?
does it have a choke or enrichment jet for cold start that could be stuck or leaking.
is your cooling system working properly? when you say warm is it overheating? is the tattle tale still working?

you may have already checked a good portion of these... if so what were the results.

Sean

Re: 50 hp Bigfoot 2003 runs rough when warm.

thanks Sean

it's EFI and I justed checked the high pressure fuel pump pressure. Its reading 20psi and it should be 42-44 psi. I'm not sure if I should change the fuel regulator or fuel pump.

Re: 50 hp Bigfoot 2003 runs rough when warm.

can you test pressure prior to the fuel regulator? perhaps then you would know if fuel pump or regulator. both are likely a bit pricey.
hoping this post will serve to bump your topic and get a better answer for you.

Sean

Re: 50 hp Bigfoot 2003 runs rough when warm.

Thanks for the help. I found the problem, it was bits of rubber hose stuck in the float needle valve. I should thank the US GOV. for adding ethanol to our fuel.