70 hp johnson/ intermitent fuel starvation?

[baxman]

Hi, I have a '89, 70 hp johnson VRO. It will start fine and run fine for a few minutes at WOT. Then it starts cutting out and eventually looses power but doesn't stall. Other times it will run fine for the warm up period, then when I'm ready to pull a skier and give it full throttle it just bogs down. I shut it down a leave it for 1 hour, it starts and then runs perfect for the rest of the weekend. Sometimes it runs perfect without it having its little "bog down/rest period", so I don't think it is an overheating issue. I have 2 portable gas tanks and they are vented properly and the problem happens with either tank. If it was sucking air or the carbs are gummed up wouldn't it run poorly all the time? I've checked the plugs after "bog down" and they are dry, like its not getting fuel. Also checked the fuel filter and it is clean. Could the VRO system be causing this intermitent problem? I'm thinking of disconnecting it and just mixing my own gas just to see what will happen.<br /><br />All suggestion appreciated.<br />Thanks

 

[OBJ]

Re: 70 hp johnson/ intermitent fuel starvation?

Hello baxman and welcome to the forums.<br /><br />Couple possibities come to mind for your problem. Sticky floats or some junk floating around the carb bowls. Try running some fuel system cleaner through it for a tank or so and see if it helps. Something like a 2+4 from Bomby is good or SeaFoam.<br /><br />Would be a good idea also to check all the fuel lines. Make sure they are still plyable and havn't lost their grips on connection points. If you find them hard, replace them.<br /><br />If the fuel system cleaner doesn't work, it's probably time for a carb cleaning/overhaul.<br /><br />Keep us posted.....thanks.

 

[martin1b]

Re: 70 hp johnson/ intermitent fuel starvation?

I had the exact same problem with my 89 48hp Johnson. The solutions with mine was that there was a hairline crack in the fuel line that is IN the gas tank. It was on the upper area so when the gas was splashing on the crack, it was fine, but other times, not. When the tank was full, ran fine. You mentioned 2 tanks. Are you using the same fuel line for both when going into the tank?<br /><br />Might be your problem, might not be. Thought I'd post my $0.02.

 

[baxman]

Re: 70 hp johnson/ intermitent fuel starvation?

OBJ,<br /> I will try the fuel system cleaner and check all the fuel lines, it seems the easiest thing to do first.<br /><br />Martin,<br /> There is only one external fuel line with quick disconnects at motor and on tank, but the internal fuel line thing sounds interesting as the tanks were bought at the same place and same time, maybe a manufacturer's defect?<br /><br /> I will try these things on the weekend and let you know what happens in a week when I get back from my WEEK OFF

 

[papasage]

Re: 70 hp johnson/ intermitent fuel starvation?

check the coils sounds like one is breaking down had that to happenn to my 1974 evinrude . it had a crack in it . after replacing it it ran good . <br /> befor i would run a short distance and start loosing power .wait a few minutes and it would git on plane and then loose power again . papasage

 

[baxman]

Re: 70 hp johnson/ intermitent fuel starvation?

Things got worse but now all is good.When I started the motor on the weekend it was idling rough and the it would stall. Then it wouldn't start at all. Trailered it to the marina.3 hour round trip. The mechanic looked at it the next day. He did all the checks and tests and said it was probably the power pack. Replaced power pack. Ran like a charm for the rest of the week.