70 hp motor starts but wont idle

[cerikson3698]

hey I fixed my starter problem thank you guys so much for all your help, got my boat running took it for a spin then about 20 min into it I put the motor in idle to switch drivers then the new driver put it in drive and it stalled. long story short it will start then idle for about 5 sec then stalls. We got stuck out on the river and had to paddle the boat back in, it really sucked. Is this something to do with the idle speed and if so how do I change that I do not have a tac on the boat. Any advice will help thanks in a advance.

 

[kynolan2183]

Re: 70 hp motor starts but wont idle

if it ran for twenty minutes and then woukd not idle to me it sounds like a tank vent problem.
Did it idle at the ramp backing it off the trailer?

Kyle

 

[tashasdaddy]

Re: 70 hp motor starts but wont idle

that is a classic time for several things to happen, a coil get hot and fail, crud to break loose in the carb, and clog idle jets. if it idled when first started, do the following.

start with the basics, there is a troubleshooting procedure to follow. compression on all 4 with all the plugs out. needs to be above 100psi, and the numbers need to be within 10% of each other. spark with a spark tester ($10 auto parts store) must jump at least 1/2 inch bright blue spark. Record these #s for future use with the motor.

if these are all good, then we look at the fuel system. i' betting 99% on dirty high speed jets. but could also be weak fuel pump. air leak in fuel line. clogged or closed vent on fuel tank. is the primer bulb, collapsing (sucked flat)? this should keep you busy today.

 

[cerikson3698]

Re: 70 hp motor starts but wont idle

yeah the motor started up on the first turn when we put it in, we let it idle for about 10 min it was working great. Then like I said switched drivers about 20 min and she stalled and then would not start back up. We got it started one more time but then when I popped it in gear it stalled again. The fuel bulb does not seem like it is acting like it used to, it is not getting really hard almost sounds like there is air in there not sure what that means but probably not good any thoughts. I am going to start doing all the things that tashasdaddy said but any other thoughts would be great

 

[tashasdaddy]

Re: 70 hp motor starts but wont idle

if the bulb didn't get hard the needle float valve is probably not working properly. but, follow the steps above, no point in throwing parts at it, until we are sure.