'88Johnson 90HP Fuel delevery problem

1988 Evenrude 90 HP VRO<br /> Bought boat with following symptom-. Starts and runs good but after running at mid to full throttle for less than one minute it acts like it's running out of gas. After idling for a short time the same thing happens. Chocking seems to help and starting fluid in the intake brings it back to life. Squeezing the ball doesn’t change anything. The ball stays hard.<br /><br />I’ve cleaned the fuel filter. I’ve tried two external tanks (water in inboard tank?) and two hoses with balls. I took the fuel pump apart and checked the hoses as best as I could. No change. People tell me I should rebuild the carbs but I’ve been around engines enough to know that this problem must be something that is common to all four cylinders. What am I missing? This can’t be this tough.

Re: '88Johnson 90HP Fuel delevery problem

I agree with those people.Sounds like a classic foul restricted carburetor/s issue.BTW,don't use starting fluid in a two stroke outboard unless you want to add pistons to the parts list.A spray bottle of premix is the prefered fuel.Also ,bare in mind that running the engine with fouled or restricted carbs can cause some serious cylinder issues in short order.Only way to properly service the carbs is to remove and completely dismantle each.<br /><br />Oh and welcome to iboats Swazo.

Re: '88Johnson 90HP Fuel delevery problem

Thanks ob, I have limited experience with outboards but lots of trouble shooting exposure. Help me understand how four components can all have the same intermittent failure at the same time. Could be I’m wrong but it just doesn’t add up. Have others seen this symptom be carb related?

Re: '88Johnson 90HP Fuel delevery problem

More than likely the needle valve in the carbs are gummed up and after you burn all the fuel out of the carb bowls the motor begins starving for fuel. The probable reason you have intermittent failure at the same time: All 4 carbs had the same fuel for the same amount of time and they all degraded and turned to gum at the same time.

Re: '88Johnson 90HP Fuel delevery problem

Possibly your suspicion of a fuel problem could be in error? Failing ignition could resemble that scenario.<br /><br />To check that possibility, remove the black/yellow wire from the back of the ignition switch. If the problem ceases to exist, replace the ignition switch.<br /><br />Note that with that black/yellow wire removed (kill circuit), it will be impossible to shut the engine down by turning the key off.

Re: '88Johnson 90HP Fuel delevery problem

I believe that 90 only has 2 carbs, 2 cylinders on each, so all it takes is one to be fouled and running lean and your gonna lose half of your cylinders and run rough or stall. This is why when you choke it, it comes back to life, same with the starting fluid, which as ob said, is a not a good idea on a 2 stroke, they now make it with lubricant in it, but you should never have to use it in the first place.<br /><br />Rebuilding carbs is easy and cheap, pull them, soak them and put new kits in. Get a manual and do a link and synch and you'll probably run a lot better.

Re: '88Johnson 90HP Fuel delevery problem

Thanks everyone. I understand your concern about starting fluid but all I did was give it one short squirt when it was losing power to verify that it was not an electrical problem. I think you might be right about two carbs. That sounds more consistent with your recommendation. I believe that the advice I’m getting is from people that have experienced these types of failures. Can I clean the carbs without the kit? It sounds like the float bowl is going dry. One gasket

Re: '88Johnson 90HP Fuel delevery problem

Swazo.... The reason I mention the possibility of an intermitently shorting ignition switch is that those switches, if faulty, have been known to operate normally when first started, but after a very short run start to develop a weak short resulting in the ignition becoming weaker as time goes by.<br /><br />The shot of starting fluid would blast away in the combustion chamber even with the weak ignition.<br /><br />You state in your first post...." after running at mid to full throttle for less than one minute it acts like it's running out of gas."<br /><br />That indicates that the engine was running normally at full throttle for a very short time and the carburetors were operating as they should. It's been my experience that carburetors do not come and go, they're either good or bad, and if bad... the engine wouldn't hit full throttle even 5 seconds, let alone 30 seconds. Possibly you've come across something new in the carburetor department, and if so, I'd be interested in what you find.

Re: '88Johnson 90HP Fuel delevery problem

Swazo,<br /><br />Joe reeves brought up an excellent point. Disconnecting the black / yellow is a fast fast way of ruling out electrical or switch problem. If symptoms persist I'd suspect something else. <br /><br />Have you figured it out yet?

Re: '88Johnson 90HP Fuel delevery problem

disconnecting one wire for a test is a lot easier and faster, than tearing down the carbs, and finding them same problem later. remember you will have to choke it inorder to stop the engine, as this wire disables the kill switch.

Re: '88Johnson 90HP Fuel delevery problem

Swazo,I'm still not clear on whether you were able just initiate the key primer and get the engine to pickup or whether you had to inject the starter fluid to get it to pick up.Your engine doesn't use a choke but rather a fuel primer.

Re: '88Johnson 90HP Fuel delevery problem

I could have explained my symptom better. The motor starts and runs good initially. It does seem to like a little extra throttle out of gear to start. When I first tried the boat the motor would stall when first accelerating from idle and the ball would not always stay hard. It did this same stall from idle thing once or twice the last time I tried it in the water. The main symptom is that it acts like it runs out of gas within a short time from being run at high throttle. It will die unless the throttle is brought back to idle. If run on idle for a while it will repeat the same scenario after running a shorter time after the initial high speed failure. Chocking makes it run longer/better but not good. The shot of starting fluid made it take off fast. It does run fine at low throttle or idle. At this time my guess is that both float bowls are running out of fuel and when idled again they partially fill up only to empty again. I got a repair manual and my plan is to try removing the yellow wire at the switch first. I might install another switch so the spark can be grounded to stop the engine or use my VOM meter to test. ( If the switch is working I should have constant voltage from this wire to ground) After that I will remove one carb and test the fuel pump. If everything else tests good I will rebuild the carbs. Does this sound like a plan?<br /> Just got back from the Minnesota walleye opener so now I can work on this boat again. Oh ya we banged a bunch of nice fish. First good trip this year.