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35hp motor problems

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Jabbo100

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First of all nice site!! I have a '96 Johnson 35 hp J35QLEDC. A couple of years ago I removed the vro on the motor so I don't know if that has anything to do with this problem or not. The motor will run pretty good on the trailer and even times going up river at wot. Then sometimes it will either just lose power like you unhooked the fuel line. When running good it will do about 30 mph loaded. Then I can feel it lose a cylinder or something and it goes down 2-3 mph but continues to run. Also it will be hard to start sometimes after we sit and fish for a couple of hours. After it finally cranks, it will not be running smooth for a while like one cylinder is not firing, then all of a sudden you hear it clear up and it runs smooth. I have rebuilt all 3 carbs and changed the power pack and coil. Yesterday pulled all 3 plugs separately and they are firing. Ordered new fuel filter but was not clogged. Replacing all fuel lines today. Also noticed a little gas/oil below one of the fuel pumps so I ordered the large o-ring that goes in the pumps. Sorry for the long post. Thanks in advance!!
 
They run good on the trailer because there is no work to do for the prop.------Does the spark jump a gap of 7/16" on the 3 leads , yes or no ?----Every dealer I have talked to has said ---" take that oiler off and throw it away as far as you can !!------Have you installed a new water pump impeller ?
 
The water pump impeller was changed a few years ago by a mechanic. As far as the spark gap not sure on that one. What is the best way to determined that?
 
There are simple test devices you can buy or you can make something with wire / glue / cardboard.----Oh---I have a bunch of these motors for parts / rebuild !
 
Ok so I did the spark gap test with a used spark plug and all three put out a good spark. Also I was looking around the fuel pumps and noticed where both of them mount around the small o-ring the plastic flange was flared out like they were tightened too much. So I ordered 2 more.
 
50:1 is recommended.-----But 40:1 will do no harm at all and may make the engine internal parts happier and live longer !
 
Well after I installed all new fuel lines, new caps for fuel pumps, o-rings, plugs and filter I thought I had it fixed. It did do better going up river. Cranks better and seems like all cylinders are firing. So we fish all day moving multiple times with no issues. So we head back down river which is about a 10 minute ride and it does good. Get to landing switch off and back truck in. Start to crank and it will not. When it finally does it's running really rough and not on all cylinders seems like. I've got the fast idle up and it sounds like it's barely above idle speed. After about a minute or 2 of this it finally kicks in and revs up to normal so we can load it. I don't know whether this is a fuel problem or an electrical problem. Sorry for the long post but this is very frustrating and I've about had enough of this motor lol.
 
Ok another question that might have something to do with this or might not. I removed the vro a few years ago. What is the process to remove the vro? Maybe I have done something I was not supposed to or still need to do something to it.
 
You take that " mickey mouse oiler " off and heave it over the fence.------Then hook up / join the fuel hoses that you see there.---Leave the wires unplugged.----Test run with another tank and hose.
 
Ok so have been out 3 more times. Motor runs great top end. But same problem as before with it sitting after running it. When I try to crank after I've run it it's hard to start. I even have to choke it sometimes. And then when it does start, I will have the fast idle all the way up and it's barely above an idle. This may go on for 30 seconds to a minute or two. Then all of a sudden it kicks in and idles way up and I lower the fast idle.
 
Jabbo100 said:
Ok so have been out 3 more times. Motor runs great top end. But same problem as before with it sitting after running it. When I try to crank after I've run it it's hard to start. I even have to choke it sometimes. And then when it does start, I will have the fast idle all the way up and it's barely above an idle. This may go on for 30 seconds to a minute or two. Then all of a sudden it kicks in and idles way up and I lower the fast idle.
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So you did not do what I suggested as far as putting a spark tester on out on the water when it failed again 3 times?
 
So like some people have already stated I'm going to have to "catch" my motor when it is acting up in order to diagnose this problem correctly. Motor runs good on muffs and I can't duplicate the problem. So with that said, besides checking for spark, what are the checks I need to make and what are the "special tools" I'm gonna need to do the checking if any? I know the first thing I'm gonna check is to make sure it's not going into SLOW mode. After that what's next? Thanks again for all the help!!
 
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So after a bunch of trips to the river, some testing and some fishing, I think we have finally figured out where my problem is. The five pin connector on the power pack. Don't believe the power pack is the problem unless one of the five male pins has an intermittent connection going down into the mold. We stumbled upon this by just pulling and twisting on cables and wires(I know I know but only way to find the problem) until we found one that made a difference. So after we discovered that pulling out away from motor on the harness right above the connector worked, I tied a string around it and tied it down to the bottom spark plug and problem solved. So now I've just got to figure out if the problem is in the harness or in the power pack connector. Thanks for all the help and hopefully ya'll can give me some tips to continue fixing this problem.
 
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