73 Johnson 65hp run issues -**New info posted!

[stacyg]

I put the boat on the lake today and it didn't want to start at first. Finally started up but seemed to take a bit to get up and go. Finally got the boat to get up to around 23mph on my 16' fishing boat. I think it should go faster, it planes out but just seems like the motor has more to give. The biggest problem is when we were done, pulled up to the dock, killed it, backed down the trailer, resarted right up, backed away from dock and boom, it died and wouldn't start again. Cranked it for 10 minutes off and on and nothing, like it is not getting gas or is flooded. I pumped the ball and it is tight. I did not get to try it again on muffs after we got home, I will tomorrow. Any suggestions?

I have good compression on all 3. I just rebuilt the carbs. prior to carb rebuild it would die at slow speeds, would be hard to restart but I had two or three more mph WOT.

 

[tashasdaddy]

Re: 73 Johnson 65hp run issues

Re: 73 Johnson 65hp run issues

good compression tells us nothing, what are the actual numbers. check spark on all 3 cylinders, jump 1/2 in with spark tester, available at any autoparts store.

read ethanol here, http://forums.iboats.com/showthread.php?t=299680

post your findings.

 

[stacyg]

Re: 73 Johnson 65hp run issues

Re: 73 Johnson 65hp run issues

I don't recall compression exactly but as i recall was right around 115 each. I will recheck though since that was a while ago. As for the spark tester. I cannot seem to find one of these around here. The only thing I can find is one you place on the outside of the wire and it reads spark or no spark. I know what you are talking about but cannot find it. I will call Napa tomorrow and see if they have one, guess I have not checked there yet. I will let you know what I find out. May be a couple days.

 

[stacyg]

Re: 73 Johnson 65hp run issues

Re: 73 Johnson 65hp run issues

ok, well the compression tester I had before was obviously broken. I went to Harbor freight and bought a new one. The one I had before would not take readings at all now. Anyway, compression is:
#1 just over 95
#2 just under 105
#3 Just under 105

I have heard 10% variation. It seems like I am within that. Am I ok, or do i have to tear this bad boy down?

 

[stacyg]

Re: 73 Johnson 65hp run issues

Re: 73 Johnson 65hp run issues

Tasha'sdaddy
Just checked the spark with a spark tester. I have strong blue spark at 1/2"+ between electrodes.

I also just decarbed the motor with seafoam. Got a bunch of black stuff out of the exhaust. Funny thing is now it appears compression actually dropped a couple psi on each cylinder. Here is what they read after decarb.
#1 94
#2 103
#3 103

In my tank the motor now does this: Starts but takes it a bit, (starts right up on muffs and runs completely different). Going to WOT it sucks air and dies, have to kinda throw and baby it it up there and then it revs up to WOT, once i get to WOT it runs good. It even runs at slow speed better after I get it up to WOT for the first time but still seems to die after it runs for a bit. It's the bogging down that gets me and I think is at the heart of the problem. I really think there is still something going on with the carbs, but I do not know where to start. I am at 5800' elevation. however, the motor has always been in colorado as far as I know but that does not mean anything I guess.

I also wanted to say I am using 85 octane gas. I am told that will not cause it to run as it is, but I plan to use 87 octane min going forward. Should I just get higher octane gas and try it with that?

Stacy