70 hp yamaha need help!

[yachtmaster165]

i have a 70 hp model 70CE tiller. i just bought it . it seemed to run fine on the test drive but was a little hard starting and wouldn't idle .<br /><br />now two weeks later it won't run. so i checked the spark . it has spark, i sprayed some gas in the carbs it fired and ran reved up but stalled when returned to idle. so i too the fuel lines off the carbs to see if fuel pump was pumping. wasn't pumping much. so i removed fuel pump dis mantled it and the diaphrams are fine. the gasked on the back for the pulse looked bad so i mad a new one and installed it. now it pumps fuel to the carbs. but still won't run. i checked compression it is about 150lbs in each cyl. <br /><br />any suggestions?

 

[vinney]

Re: 70 hp yamaha need help!

Remove and clean the carbs. Watch the float height very carefully. Set them level. Its a very easy carb to clean/rebuild.

 

[yachtmaster165]

Re: 70 hp yamaha need help!

how do you know where the floats should be?

 

[yachtmaster165]

Re: 70 hp yamaha need help!

checked carbs and floats they seem fine. any ideas?

 

[vinney]

Re: 70 hp yamaha need help!

Is there fuel in the carbs? If there is fuel in the bowls of the carbs. Take the air box off the front of the carbs. As you crank the engine cover one of the carbs with your hand. The engine should run. If this starts the engine your problem is in the choke/inrich circuit of the carbs.

 

[yachtmaster165]

Re: 70 hp yamaha need help!

Vinny thanks<br /><br />it starts somewhat with the carbs covered. how do you adjust the enrich circuit? i also had the ckoke on.

 

[jim dozier]

Re: 70 hp yamaha need help!

First, go to the bottom of this web page and buy a manual for your engine. Best $30 you will ever spend on your boat. This won't be the last time you will need it.<br /><br />You need to find out why fuel isn't getting into the engine.<br />1. Start at the tank and check the fuel lines back to the engine. Can you pump the fuel bulb? Is it picking up fuel? Does it eventually get hard? <br />2. Why did you make a fuel pump gasket? Is your gasket sealing correctly? Is there fuel in the carburetor bowls?<br />3. Will the engine run at speeds other than idle or will it not run at all? Remove the carbs and do a thorough carb cleaning/rebuild. Remove and clean the carbs with solvent and compressed air. Install the parts that come with the rebuild kit. Set the float height and adjust the idle mixture screw as per the manual.<br />4. Tune the idle in the water in gear.