1980 85HP Johnson

This is a petty lengthy discription of the problem I am having with my motor. When I first start it up in the morning it idles rough and idles rough all the way out of the cove that I launch from (approx 1 mile). After I get out of the NO WAKE zone I push down on the throttle and I hardly get anything for acceleration. It may run this way for about 5-10 minutes and then suddenly it will kick in ,plane out, and run great for the rest of the day. Eve if I turn it off it will run great. It is not a build up of RPMs and power but more like it just decides to kick in. My gas is clean.....my fuel filter is clean.......my plugs are good.......I have a maintenance manual for this motor but I can find nothing that addresses this specific problem. <br />I'm gonna relate some other things that are occuring that may or may not be related to this problem: <br />1. When I pump up the fuel bulb it will pump the gas into the motor and slowly get harder to pump but it never gets <br />so hard that it cannot be squeezed a little with a good amount of pressure <br />2. If I am running to a fishing area for approx 20-30 minutes it may never "kick in" but when I start it to leave it <br />might "kick in" on start-up and then run right all day. <br />3. I have been dealing with this for a while.......it seemed like it took longer for it to "kick in" last winter when the water <br />was around 45-50 degrees (I live in Texas) and it seems to "kick in" a little sooner now that the water has <br />warmed this summer <br />4. Could I be dealing with a thermostat malfunction........although it would seem (at least to me) that if it was a cooling <br />problem related to a stuck thermostat that the transition would not be so abrupt. BTW my overtemp warning horn <br />has never gone off. <br />5. A friend with a newer Johnson said that in his book that there was an electrical component that allowed tha motor to <br />operate during a overheat condition at limited rpms supposedly to get you back to the ramp. Does my motor have <br />this feature.........It says nothing about it in my book. <br />6. Could I be dealing with a malfunctuion with the check valve in the fuel line downstream of the bulb........like I said <br />earlier you can pump it up but not to rock-hardness.........it will always allow for more squeezes. <br />That's about all the info I can give unless any of you guys want to ask any questions.............any help would be greatly <br />appreciated. <br /><br /><br />thanks <br />Benny

Re: 1980 85HP Johnson

2 things come to mind. Fuel pump may be leaking fuel back thru the pulse hose into the lower block. That would explain your bulb never getting hard too. If this is whats going on with your motor the lower cylinder is getting a fual air mixture above the flammability limits (too rich to burn)<br />Clean all your coil grounds, although this problem usually occurs opposite of yours. You generally lose a coil as the motor warms up.

Re: 1980 85HP Johnson

First identify whether it's a carb problem or an ignition problem. Take a can of starting fluid with you and see if a squirt down the carb's makes it "kick in". Also if you suspect an RPM limiter pull the temp sensor or ground it out to see if you can mimic the undesirable chariteristics.

Re: 1980 85HP Johnson

Don't use starting fluid on any 2 stroke motor as it has no lubricating properties. And your motor doesn't have a SLOW system to slow the motor down when it gets hot.

Re: 1980 85HP Johnson

OK, two questions.......first what is the fuel pulse hose and if it is leaking back throughinto the lower block, what is the fix for this? Rebuild fuel pump?......and secondly if I squirt starting fluid into carbs and it does "kick in" what does that tell me.

Re: 1980 85HP Johnson

Question 1, The pulse hose is the hose from your fuel pump to the engine block. Some fuel pumps didn't have one. They mounted directly on the hole to the block and got the pulses staright thru the back of the fuel pump. I believe yours has a hose. If you are leaking fuel back into the block the cause is a rupture in the fuel pump diaphrma, The fix is a rebuild of the fuel pump. <br />Question 2, Mostly nothing, starter fluid has such a wide flammability range that even if you have a cylinder loaded with too rich of a gasoline mixture it will still ignite when you spray starter fluid into it. It might tell you if your sparkplug is firing but there are much better ways to test that. <br />I repeat, starter fluid is a No No for 2 stroke motors.

Re: 1980 85HP Johnson

I have always suspected the fuel pump but I keep coming back to the question of WHY does it only do this part of the time......if the diaphram is damaged why does it "kick in" after a period of time.

Re: 1980 85HP Johnson

Here's how that could happen. You pump the bulb up trying to get it hard. Once the carb bowels are full anymore you pump goes tru the diaphram and straight into the crankcase. You fire up the motor and one cylinder is too rich to burn. Gasoline will only burn in a 1.4% to 7.6% mixture with air.<br />Once your get running for a while the motor pumps off the excess fuel and reaches the flammable range and starts firing. <br />What do your sparkplugs look like??

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What the hell happened, 4 posts from one click.<br />Anyway, you can test this by pulling the pulse hose off the fuel pump and squeezing the bulb up and the keep squeezing it and see if any fuel comes out the fuel pump.

Re: 1980 85HP Johnson

And I guess if I do get fuel out of the pulse hose then it is probably by-passing through the diaphram.......right?

Re: 1980 85HP Johnson

Yep