2003 yamaha f90 carb question "rodbolt" mabye

dragracer5256

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Engine wont start unless you spray brake clean in filter. Took carbs off needles were stuck (found problem right, NO). Blew brake clean through all circuts, other than stuck needles no trouble found in carbs, very clean. Cleaned separator, hooked inlet fuel line to my fresh clean gas can, flushed system to carbs, hooked lines back up, pumped bulb up, still no start. Slightly hits a little, can open throtle up to get into main metering circut and it runs nice for a few seconds then dies. Fuel pump squirts good while cranking. While I had carbs off I could blow through inlets with floats hanging but felt slight restriction, didnt seem to bad. Did i read in other post that there is screen in inlet at carb? I did not remove hose on carb as it was easier at T fiting. Also motor has autolite plugs in it and I see it calls for NGK. Are these motors very picky when it comes to plug selection? If I take carbs back off does the Idle fuel flow through the tiny sets of holes just past throtle blade or in larger hole that is related/next to the miwture screw? Also I did check the electronic choke valves and they do slowly move when voltage aplies and if I remove these and hold fingers over holes engine runs. Does all fuel flow past this electronic needle for idle or is it only to do with fuel for aditional enrichment. Could this needle be to low at home position causing lack of fuel? Seems to be allu. slide measures out about 1/2 inch from base of plastic when home. Was able to blow through small holes beyond throtle blade in carb just fine. Which way to go from here? Thanks a bunch for help!
 

99yam40

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Re: 2003 yamaha f90 carb question "rodbolt" mabye

Do you have a Yamaha service manual for your motor? If not get one and read. There are ways to troubleshoot all systems on the motor,and it will tell you what tools and equipment is needed.
I would have to say it sounds like your carbs need to be pulled and cleaned properly. The enrichment system is for cold starting and running until warmed up, then it turns itself off.
 

dragracer5256

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Re: 2003 yamaha f90 carb question "rodbolt" mabye

No I don`t have book, but im 99.9% sure no orfices in these carbs are pluged up. What to check?
 

rodbolt

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Re: 2003 yamaha f90 carb question "rodbolt" mabye

carbs are still clogged or the inlet screens are stopped up or both.
do it again.
 

dragracer5256

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Re: 2003 yamaha f90 carb question "rodbolt" mabye

Hey just want to thank you rodbolt, restriction was in pilot jet under rubber plug (guess idle circut feeds through there). When I initally took apart and found everything to be so clean and needles were stuck (thought I found problem) didnt look deep enough. Had no clue pilot jet hidden under rubber plug. DAMN. Anyhow thanks again. If you could give me address I could mail you something to show apreciation. It was helpfull to get professional opinion because my time is very limited right now.
 

rodbolt

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Re: 2003 yamaha f90 carb question "rodbolt" mabye

no worries glad we could help.kind of a short answer but if it runs when you spray a fuel into the intake either the carbs are clogged or there is no fuel in the bowls.
 
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