1987 Johnson 40 hp cranks but wont start

[Rowan]

I use the boat almost everyday. It cold starts great every morning, but lately, after I run it and turn it off, if it doesn't start on the first crank then it takes forever. Now, it didn't even start at all this morning.

No spark, (my original post said it had good spark but it doesn't - I'm going to disconnect the kill switch and try it) but it's got good compression, new fuel, tank, and hose, but it just cranks and cranks but doesn't start. THis morning it actually did turn over and it ran for about a half second. THis happened about 5 times out of 50, then we went and got new fuel, tank, and hose. However, this didn't change a thing. We squirted starter fluid into the carbs (I now know not to do this) but it still didn't start.

If it was bad/water in fuel, is there a way to get the rest of the bad fuel out of the engine block? I primed the ball before starting but I had to continue to prime it every now and then throughout the process of trying to crank it up. It seems like the ball gets full but I can continue to pump fuel with it like there's a tiny leak somewhere or not a great seal on a hose clamp or something, but it is a very small leak.

Any help would be great; I'd like to get back to work.

 

[steelespike]

Re: 1987 Johnson cranks but wont start

Re: 1987 Johnson cranks but wont start

Don't keep your motor model a secret.
It sure seems like some sort of ignition problem Could any number of things in the system I'll leave suggestions to the ignition experts.I would suggest you check the kill switch circuit.

 

[psteurer]

Re: 1987 Johnson cranks but wont start

Re: 1987 Johnson cranks but wont start

What is the horsepower for this motor? You mentioned that you can pump the bulb but you can continue to pump it like there is a leak somewhere. It is normal for you to have to pump the bulb again after you have tried to start the motor. That means that the fuel is flowing into the engine which is what is suppose to do. But if you prime the bulb and you cannot get it stay hard, then you have to find that leak. It could be that the needle valve inside the carburetors is not closing and the carbs need to be rebuilt.

You might also want to recheck your spark. Is it a good blue spark that jumps at least 5/16 of an inch?

 

[tashasdaddy]

Re: 1987 Johnson cranks but wont start

Re: 1987 Johnson cranks but wont start

WHAT MOTOR???? spark has to jump 5/16 inch as said, compression has to be with in 10% of each other. starter has to turn motor +- 300 rpms for it to start. fully charged battery, good cables, with clean connections.

 

[Rowan]

Re: 1987 Johnson cranks but wont start

Re: 1987 Johnson cranks but wont start

Sorry for not mentioning horsepower guys .. it's a 40 hp 1987 Johnson .. don't know the model number but will get it tonight. Will also check the spark again. Battery was hooked up to vehicle providing plenty of charge and it was spinning as fast as I've seen it before. I can pump the ball until it's hard and it will stay that way until I crank on the engine a few times so it doesn't seem like that's the problem, and the kill switch lanyard is engaged like it should be - that doesn't mean it's working but... seems like it must be the spark. I'll try to find a "step by step" on how to check the spark unless someone feels like explaining it. THanks, this site has been a GREAT resource to me.

 

[tashasdaddy]

Re: 1987 Johnson cranks but wont start

Re: 1987 Johnson cranks but wont start

check spark with an adjustable tester, $10.00 any auto parts store, adjust it to 7/16 inch, connect one end into the plug wire, the other to ground on motor, turn key to on, then turn motor over like starting.

compression test, ethanol, fuel lines read here.

http://forums.iboats.com/showthread.php?t=299680

 

[ba_50]

Re: 1987 Johnson 40 hp cranks but wont start

My '79 johnson 35 starts hard in the morning if the motor has been tipped up. It seems to flood when first starting. It had a new fuel pump kit put in last year. I suspect there is more to it in my case. It might help to leave the motor down once and see if it starts easier. I doubt if yours has fuel injection.

 

[Rowan]

Re: 1987 Johnson 40 hp cranks but wont start

Yes, mine does that too...when idling with the motor trimmed up it's fine, but as soon as I put it down I have to give it throttle/rpm's or else it will cut off; not a big deal to me, it's been doing that for years but I don't know what it means.

Just tested the spark and there is none!! I was wrong - no spark!! I'm about to search the forums for insight but if anyone has input I'm all ears.

 

[bktheking]

Re: 1987 Johnson 40 hp cranks but wont start

Yes, mine does that too...when idling with the motor trimmed up it's fine, but as soon as I put it down I have to give it throttle/rpm's or else it will cut off; not a big deal to me, it's been doing that for years but I don't know what it means.

Just tested the spark and there is none!! I was wrong - no spark!! I'm about to search the forums for insight but if anyone has input I'm all ears.

Start with wiring, check wiring to lanyard or kill switch and to ignition switch, fuses if it's got one.

 

[EN2]

Re: 1987 Johnson 40 hp cranks but wont start

Unplug big red plug on powerhead,jump solenoid starter will crank, check for spark.

 

[Doyle Johnson]

Re: 1987 Johnson 40 hp cranks but wont start

Had the same problem with my 85 horse, Come to find out it was my power pack, now it runs fine. That might be your problem !

 

[Rowan]

SOLVED Re: 1987 Johnson 40 hp cranks but wont start

SOLVED Re: 1987 Johnson 40 hp cranks but wont start

It was the kill switch - I disconnected it and it fired right up. Now I just need to replace it so I can run the boat safely. Thanks to everyone that gave me input; this site is great.