Fuel Pumps

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redrider24940

New member
Joined
Jan 3, 2006
Messages
51
Age
44
Location
Kiel Wisconsin
Just a question but how do you check to see if you have a good fuel pump? If I have the lines off of the carbs when I pull it over I get gas coming out of the lines. I kinda looks like it is pulsing. Is there a "Right" way to check this? It is on a 97 sx 700? Thanks
 
What you are seeing is probably normal operation, it will pulse. The only way to know if it is not flowing right would be if you know what a good pump flow looks like and yours is a lot less.
Yamaha and Mikuni would have flow specs, but good luck getting them.

The pump is checked by doing a visual check of pump components.
Also, there should be no flow when blowing with your mouth-
-through the pulse hose port (the hose that attaches to the crankcase).
-through each fuel outlet port while blocking the other outlet port(s).

The normal symptoms for a pump problem would be engine fuel starvation at high speed or fuel entering the crankcase through the pulse hose.
 
Always possible but other causes would be more likely, a bad pump would usually cause it to run okay to a point and then stumble or bog - and the pumps are normally fairly reliable. Dirty carbs, clutching problem, worn belt, low compression, plugged muffler ....
Is it running on all three?
 
Yes, I have spark in every cylinder and heat in all three pipes. Clutching same and new belt. Carbs just cleaned twice and motor rebuilt at the begining of last season. New coils and plugs. Went through all wires and checked to see if any were wore through but none were. Can't figure it out unless I got bad 93 octane gas?
 
How and when did the problem start?

See what happens when you choke it while accelerating.
 
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Sounded like i fouled a plug last year last day of riding and put it away. Thought it was a coil and switched them with 3 other ones same thing. I believe it is the middle cylinder. Can only get 65 out of it and it climbs slow
 
Took the carbs back out tonight and gonna clean again. Clutch side spark plug not showing much on plug after pulling it. other two look fine (cardboard brown). Hopefully it is just the carb. Gonna check compression this weekend. Will keep you posted
 
i have a simmilar prob. only its the mag side and no heat in the pipe at idle for sure and not sure off idle. i need to check everything out as well. let us knowwhat you find and i will do the same.
 
I will be putting the carbs in later tonight. sled wont even idle normal. Sounds like it is running on only 2. Boggy and little acceleration with Clutch side cylinder sputtering and backfireing. Will keep you posted
 
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