'74 Evinrude 85HP 85493B Won't Start

[Rowinj13]

I am fairly new to boating, I say that because I have been around boats for a long time, this is just the first boat that I have ever owned. Here is my situation I have a 1974 Evinrude 85 HP 85493B V-4 that hasn?t been run since 2009. Knowing that the engine hasn?t run, but was ?winterized? by the previous owner, I knew that there were several things I needed to do before I could get the boat running. First I bought the factory service manual, I made sure that the engine was free spinning by rotating the flywheel, I checked the compression on all four cylinders and everything was within spec. as defined in the service manual. I drained and refilled the lower unit with the proper oil, then I cleaned/rebuilt the carbs, I checked all the fuel lines and they looked clean. When I was removing the carbs I saw what looked to be oil coming from under the flywheel and running down onto the top carb, but it actually turned out to be some of the coating from the magneto (not sure exactly where it has come from yet since I have not pulled the flywheel). I have replaced the plugs with the specified Champion UL77V plugs and checked the I am getting good spark to all 4 plugs with a spark gap tool, have fresh properly mixed gasoline (50:1), have a new fuel line from the portable tank to the engine, I rebuilt the fuel pump. I verified that I was getting gas to the carbs, (I removed the fuel bowl drain plugs), and I have a freshly charged battery.

When I follow the direction for a cold start up (having it connected to muffs) the engine will turn over but not even try to start. I sprayed some pre-mix into each carb, and had the same results. When I spray a small amount of pre-mix into each of the cylinders and button everything up it will fire up for a second.

I am fairly certain that it is either a fuel problem or a vacuum leak somewhere.

Is it possible that the upper crankshaft seal has gone bad and is not allowing the proper vacuum to draw the air/pre-mix up into the cylinders, also not creating enough vacuum to pulse the fuel pump to continue to pull gas from the tank?

The factory service manual is okay when it comes to breaking things down and putting them back together but the trouble shooting section could have used a little more work. I want to make sure that I have checked everything out before I just go and start throwing parts at the engine and hope that it fixes the problem. I?m not new to 2-strokes I have worked on snowmobiles before, but this is something that is baffling me as to what it could be. I know how to do a crankcase leak down test on a snowmobile is there an easy way to do this on these engines? Any thoughts or ideas of what could be the problem or how to diagnose it would be greatly appreciated.

 

[jere1972]

Re: '74 Evinrude 85HP 85493B Won't Start

if your spraying premix into the carbs and no fire, I would say either your reed valves are all stuck, or your so out of time, wrong sensor on wrong pack terminal, i would find it very odd to have a so blown out a crankcase seal, that she won't fire @ all, if you hold your hand over the carbs you should have suction when cranking, if so revist your carbs, if not check your reeds

 

[BonairII]

Re: '74 Evinrude 85HP 85493B Won't Start

Have all fuel and air lines been replaced? Maybe you have a dead insect etc clogging a line?

 

[Rowinj13]

Re: '74 Evinrude 85HP 85493B Won't Start

if your spraying premix into the carbs and no fire, I would say either your reed valves are all stuck, or your so out of time, wrong sensor on wrong pack terminal, i would find it very odd to have a so blown out a crankcase seal, that she won't fire @ all, if you hold your hand over the carbs you should have suction when cranking, if so revist your carbs, if not check your reeds

Jere1972: Thanks for the info, I hadn't even thought of the possibility of the reeds being stuck. I will double check to make sure that I am getting vacuum at the carbs, and as you said if there is none I will check the reeds. I have never had this happen with a snowmobile even after they have been sitting in the previous owners barn for years. I'll keep you posted on how things go, unfortunately I will not be able to get to it before the weekend.

 

[Rowinj13]

Re: '74 Evinrude 85HP 85493B Won't Start

Have all fuel and air lines been replaced? Maybe you have a dead insect etc clogging a line?

BoairII: No I have not replaced all the fuel and air lines. I did do a thorough inspection of them all and they are all free from debris, are all soft, have no cracks and are all tight on the fittings they connect to. I will have to check to make sure that my oldest son wasn't messing around and maybe disconnected something, which is a good possibility. He wanted to show off to his friend how much he knew about the 1978 Jeep CJ7 we have so he took off all the plug wires, and ended up getting two out of order, so I spent a week chasing down a mysterious backfire, until I found out what he had done. It would have been nice if he had told me that he had done that because that would have been the first thing I checked. So I will have to go over all of the lines again.

 

[Rowinj13]

Re: '74 Evinrude 85HP 85493B Won't Start

Okay so here is an update. Over the weekend I was able to get back to the boat and look it over. I went back through the carbs and sprayed that down with cyclo carb cleaner (amazing stuff, works quick), after I had the carbs off I took a look into the reed cages, in the No. 4 cylinder cage was the back side of an old air box cover plug, which probably didn't help the situation. Other than that everything appeared to look good in all of the cages. I did spray some carb cleaner into the cages and was surprised at the amount of varnish that was in there. I put everything back on the engine and turned her over. She fired right up. I didn't get a chance to get her into the water last weekend, I am going to try to get her out on the water this weekend though. Should be a good weekend for it, they are forecasting hot weather this weekend.