Page 1 of 1

Yamaha f70 cutting out

Posted: Mon Apr 15, 2013 10:21 am
by hobbit
Hey all I have been having trouble with my motor last couple of trips. It runs good for ages but if I'm trawling after about an hour the motor just cuts out but when you start it up it will idle good but as soon as it is put in gear it cuts out again. I have to use the choke and rev the cr.p out of it then get up on the plane and then it's all good. Then after it starts doing it it will happen about every 15min when trawling or if the motor is just idleing. Starting to get annoying when it does it at shady mouth with heaps of other boats around. I have put a water seperater on to see if it was water also flushed out the cooling side of it but still doing it just seeing if any one would have any ideas

Re: Yamaha f70 cutting out

Posted: Mon Apr 15, 2013 5:09 pm
by Geraldton892
Have you checked your fuel filter seal? sounds like your fuel system isn't being pressurised enough sucking too much air and is causing the motor to starve at low revs. I had a similar problem and my filter wasn't screwed in all the way (after a service). Didn't notice it at high revs only when I was idling around; however, I did notice the smell of fuel vapours near the engine.

Re: Yamaha f70 cutting out

Posted: Mon Apr 15, 2013 5:45 pm
by hobbit
I will check that thanks also think I might change the fuel bulb thingy

Re: Yamaha f70 cutting out

Posted: Sat Oct 27, 2018 11:20 am
by dwarmo
I know its a 5 year old post however I am experiencing exactly the same problem with a F70. Wondering if you found a definitive answer. Im thinking its a fuel problem also - sucking air - replaced fuel lines and cant find any fault there.

Re: Yamaha f70 cutting out

Posted: Sat Oct 27, 2018 11:24 am
by hobbit
there is a pipe that let's water past the fuel to cool it. mine was full of sand I just removed it and cleared out. never had another issue. PM if you need more help

Re: Yamaha f70 cutting out

Posted: Sat Oct 27, 2018 12:13 pm
by mickkk
Reckon hobbit might be on to it.
Had @ mate with a near new 100 hp yam. Had the same issue, after several trips to in and out thinking that they had solved it and then having it again on the next trip. They eventually solved it and it was as hobbit said.

Re: Yamaha f70 cutting out

Posted: Sat Oct 27, 2018 3:35 pm
by dwarmo
okay thanks but cant find this pipe -The only water inlet that I can see that could get blocked with sand is the one above the gear box which is the main cooling intake (black plastic grate). Fuel is all up the top under cowling so figure I should be looking there. I can follow the fuel line in to the primary filter then fuel pump and then probably to high pressure injector pump etc.

Re: Yamaha f70 cutting out

Posted: Sat Oct 27, 2018 5:32 pm
by hobbit
it's at the back/top of high pressure pump.

Re: Yamaha f70 cutting out

Posted: Mon Sep 07, 2020 4:28 pm
by dwarmo
Hey Hobbit its almost two years on and I havent sorted this out so I can fix it myself. I wasnt sure how to PM you.
So I have had to take the motor to the Yamaha dealers a couple of times after some inevitable mud ploughing in unfamiliar waters. Would be good to be able to do this myself. Do I need a Yahoo account to pm you
cheers

Re: Yamaha f70 cutting out

Posted: Wed Sep 09, 2020 5:33 pm
by theodosius
I think there's a minimum number of posts before you can send a private message