Help! I can't get this evinrude 4hp to run.

[Daveparm]

I recently aquire this 1979 4 hp outboard model 4904D. When I pull start, it will sputter for a sec or so, but never catch and run- well I did have it run for a minute or two a couple of times, but that has been after many many pulls the short time it did run it ran smooth.

Here is what I have checked so far. Good compression 105 on both, good spark both cylinders (with new spark plugs), coils check ok with multimeter, gravity feed fuel tank taken off throughly cleaned, hose changed, new petcock and filter, good flow to carb, carb cleaned throughly (including orifices under welch).
This is a model that has a single coil and sensor under the flywheel that sends signal to the two external coils.
I am at the point where I just removed the flywheel, and nothing appears out of the ordinary (key not sheared, sensor and coil properly secured). I suspect either bad sensor, or control module, but not sure how to check either. Any ideas??? Thanks

 

[Daveparm]

Oh one other thing. When I was troubleshooting the intake I failed to check the reeds. Could that be it?

 

[oldboat1]

On the carb -- has a jet in the bottom of the nozzle the stands vertical in the carb. Nozzle should be removed and clean (soaking is best imo, then each of the small holes cleaned with thin wire and carb spray, including the jet at the bottom).

ignition -- testing for spark has to be done with a spark tester, adjusted for 3/8". If spark on each is good, do a drop test when running (pull off plug boots individually and see if rpms change). New plugs does not mean good spark.

could be reeds, as you suggest, but not real likely. Need fresh fuel. 50:1 OK on '70s models.

 

[Daveparm]

Thanks for getting back to me. I did clean the carb nozzle. I also checked for spark (one of the very first things I did) , but couldn't find my tester and put the plugs in the boots, grounded and checked spark that way. Spark seemed strong based on visual and sound snap on both cylinders. It is near impossible to start so checking it with it running isn't an option. I did pull the carb since the last post and the reeds seem ok , although I just inspected jently tapped them with the manifold still attached, so couldn't check the back side.

 

[oldboat1]

The idle needle needs to be set at about 1 1/2 open for starting, then adjust from there (final setting is typically a little bit leaner -- clockwise). Try spraying some mix into the carb throat and see if it will pop. Don't overchoke.

 

[Daveparm]

I did try 1 1/2 turns and various other setting. I also tried various choke combinations. I should mention that I have been at this for about a week now. I also used a syringe to add some fuel mix to the carb, with no luck there. If you don't think it is anything under the flywheel (sensor) I will put it back on and try a small sqrt of fuel in each cylinder via the spark plug holes. Not sure why I didn't try that, but at least that might make it run long enough to get a spark tester on it. Btw, the tester that I lost simply went between the spark plug and wire where the spark was visible through clear plastic. I don't remember there being and measurement marks on it, but I keep seeing on these outboards to check for spark distance. Is this some other kind of tester?

 

[Daveparm]

Could a bad sensor retard timing enough to keep it from starting?

 

[Daveparm]

How would I perform a leak down test on an outboard. I guess I would have to remove the powerhead and seal of the exhaust that way right? The exhaust port on the leg is open to the inside isn't it?

 

[oldboat1]

Pick up an adjustable open air tester, available at auto parts stores ($10 -$15). Plugs are removed -- tester plugs into boot, and is grounded to the powerhead with a clip. Need a solid ground. I wouldn't do anything more radical until doing the spark test. (Both plugs out while testing individual leads.)

 

[Daveparm]

Vince, I'll head to the store now and pick one up. By the way in your earlier post on the carb. The main jet is screwed into a nozzle and that nozzle is slid over a needle tube that appears to be held into the bore with a lead shot from the other side. We're you reffering to that needle tube that extends all the way through the throat? The 4 vertical and bottom hole on the nozzle is difinately clear, and the jet that feeds it is clear as well.

 

[Daveparm]

Picked up a spark tester and each cylinder easily gapped 3/8 inch. I then injected a little fuel mix in each cylinder and tried to start and still nothing. Fiddling with adjustments, and after about another 50 pulls, I decided to do another compression test. This time I got 85 on top and 65 on bottom. When I first bought the motor I sprayed some fogging oil in it before the first pull as the motor obviously not run in a while. I must have not had all of it out when I did the first test. Lesson learned the hard way with much wasted time. Am I correct to assume one of these won't run with 65 psi?

 

[Daveparm]

Any idea the aproximate cost of a mild rebuild assuming the crank, cylinder and rods are O.k. Basically gaskets, rings, bearings, and anything else that might be suggested?

 

[Daveparm]

Ok I finally figured it out and it wasn't even a compression issue. I remember that on the first compression test I used a cordless drill on the flywheel nut to turn it over as I thought the screw on top was to take the cowl off. Luckily it was siezed and I sheared it, so when I finally got the cowl off I was able to drill it out without unhooking the spring.

Back to the topic, I was thinking maybe my low compression numbers were from the lower crank speed of the pull start. I decide to see if I could get it running with less water in the tank, then fill it higher if I got it running. It would kick long enough and I was persistent enough, that I finally got it running (albeit at 2AM). Let it run for a about 5 minutes, spit nice water, but even though the throttle was set at high speed, motor was at a fast idle. Cam was opening carb to a point where it should have run faster.

You can probably guess where this is going

As this motor is semi-direct drive, I decided to pull the gear case. Sure enough the driveshaft turned very stiff and would slightly bind upon turning it. I gave it a pull (sans lower end) and it started right up. Shut it off a few seconds later obviously.

I hope this helps someone with a similar problem. I noticed a few threads when searching that ended unresolved, that could have been the same issue (one where the op could only get it to start with flush attachment was one) My low compression pull numbers were due to lack of inertia after the pull. I kick myself for not coming up with this simple solution a lot earlier in the troubleshoot process.

It was too late, and I was to happy to tear into the lower end. Hopefully it is just a binded impeller.