Running problems on F100 AETL

[Bob13007]

Hello everybody. First of all, I'm french and my English is not very good, I apologise for that. I've read some thread in this forum and think I can get a response to my problem there.
I have bought a 2003 F100 AETL Yam (67F L 10002..) that cannot start. The carbs have been cleaned and tuned by a Yamaha mechanics, news sparkplugs, filters and so... Now it start very well, idle is perfect (700 rpm). When I accelerate, everything is OK, but at 1800 rpm (this is very precise) the engine seems to be only running on 2 cylinders (it's not smoth) until I reach 2800 rpm (precise) and then everything is OK smoth again and I can run 4500rpm 5000 rpm whithout problem. When I go down at 2800 rpm the same problem is there again until I pass below 1800 rpm (always precise), now its fine again.
I think it could be the TPS. Am I right or do I have to check something else ?
Thank you for your response.

 

[rodbolt]

Re: Running problems on F100 AETL

thats an international market engine so it may be slightly different from US marke versions.
however it still goes suck,squeeze bang and blow just like ours.
there is a small check valve in the accelerator pump lines on #3 carb that can do that , also if the midrange circuits are dirty it will. also if the hull isnt on plane at that RPM it makes the engine lug.
testing ign outputs and TPS outputs at the problem RPM and load isnt difficult.

 

[Bob13007]

Re: Running problems on F100 AETL

Thank you for your response. As the problem arrive at the same RPM (1800 RPM not 1750 or 1850) I was thinking that its was an electrical problem caused by a bad information given by the TPS. I'll try the things you notice ASAP.