'79 235hp

[HannesG]

Hi all

I am experiencing difficulty starting my 235hp. I do all the usual stuff before trying like priming and so on...

It does not even make a diff when it hot or cold.

Any tips please?

 

[emdsapmgr]

Re: '79 235hp

Is the choke working? Are the plugs wet or dry? Does it have spark on all cyls?

 

[F_R]

Re: '79 235hp

Is it cranking fast enough? It won't have enough spark to fire the plugs if it is cranking less than 200-300rpm. See if it will throw a spark across a 7/16" gap (with all the plugs in).

 

[HannesG]

Re: '79 235hp

Thanks for your replies so far.

The choke is working 100% - checked that last night. Don't know if the plugs are wet or dry.

I'll check if it's cranking on that rpm's.


Just a further note: When I do crank it (when I'm on the water), it will turn a couple of times and then It will take and kick out the starter but then it will immediately die again. Is it getting enough fuel?


Thanks in advance!

 

[HannesG]

Re: '79 235hp

And yes, it does have spark on all cyl's... When it actually starts (after cranking and cranking and cranking) it runs like a sweetheart!

 

[emdsapmgr]

Re: '79 235hp

Is your engine always vertical, or do you store it with the engine tilted? Not unusual for tilted carbs to leak gas/oil mixture into the airbox cover, then be drawn into the lower cylinder,causing a rich condition ane hard starting. Check your compression. Low compression equals hard starting. On a similar note, if you have not run a can of Bombardier Engine Tuner throught the engine in the last 100 hours-that would be advised. This helps remove carbon around the rings, helping compression (both starting and idling.) Are the plugs clear of debris/clean?

 

[HannesG]

Re: '79 235hp

No, I always store it tilted.

I dont know if I'll be able to get "Bombardier Engine Tuner" here in South Africa, any other brand you can recommend?

The plugs are clean - cleaned them myself. Will be replacing them anyway shortly.

I'll also check the compression.

Thanks so far...

 

[HannesG]

Re: '79 235hp

and should it now not be cranking fast enough, what should I do?

 

[F_R]

Re: '79 235hp

The usual starter trouble diagnosis procedures. Could be

Weak Starter
Weak Battery
Bad cables
Bad solenoid
Dirty or loose battery cable connections. Don't just assume, take the connections apart (both ends) and clean them shiny bright and tihten them properly. This is the most common starter problem

Voltage drop tests across the components with a voltmeter helps. For instance if there is a large voltage drop across the solenoid, it is bad. No or negligable voltage drop across it, it is OK.

 

[HannesG]

Re: '79 235hp

Ok, how do I perform this voltage drop test. I do have a voltmeter.

Thanks

 

[mikesea]

Re: '79 235hp

Try taking some gas (mixed with oil)and using a spray bottle shoot someinto the carbs,you will need to remove the carb cover ,if the engine starts without a problem,check out your primer and make sure all hoses are connected especially the larger one that feeds it,(you can check it first)when you are priming the systen,can you hear the primer operating,it is possible to hear it operate if you can get close enough,if you cant hear it,you may have a broken connection along the way,you can also turn the red valve on the primer 90 degrees then squeeze the ball or if you have an elec pump,the primer should allow fuel to pass through to prime cylinders.As for the cranking,true if it dont crank fast enough,you will have spark problems. Does the engine souund like it cranks as always?Is the squeeze ball ok,are you sure fuel is being pumped,it might not be pumping fue and be locking up with air,or just not working at all,I think your not getting a prime for starting

 

[F_R]

Re: '79 235hp

OK, somehow I knew that was coming. To do a voltage drop test you put your voltmeter leads across the component you want to test.

For example to test the solenoid contacts you would put one voltmeter lead on one of the large cable terminals and the other lead on the other large cable terminal. Keep the polarity correct. Crank the motor momentarilly and note the meter reading. Should be very near to zero in this case. But if it should read, say 3 volts, there is a resistance across the contacts. That's 3 volts that is being wasted on the solenoid instead of being applied to the starter. It's Ohm's Law applied. E=IR where E (volts) = I (current) times R (resistance). Lessee, I think I got that right, heh.

You use the same principle to test for bad cables and connections, etc. Just put the leads on opposite sides of the unit you want to test. Resistance in the part or connection will show up as a voltage reading on the meter. You do have to keep in mind that some resistance is unavoidable. Like a battery cable has a bit of resistance, but the main thing is to keep it as low as possible.

 

[HannesG]

Re: '79 235hp

FR: Great stuff - I'll try that. Thanks a mil!

MikeSea: It's getting fuel as I can hear fuel going into the carbs every time I pump it.

 

[HannesG]

Re: '79 235hp

Had another look and it seems like somewhere something is leaking. When I have the motor tilted up a blackish oily fuel mixture is draining out of the engine cover... Could this be one or some of needles and seats that's not sealing anymore or what?

 

[emdsapmgr]

Re: '79 235hp

The 79 engines did not have the fuel primer system. They had the old electric choke/butterfly system. Make sure the choke butterflys in the carbs close fully when the choke solenoid is activated. The solenoid is adjustable. Spraying a fuel/oil mist in direct in the carbs is not a bad idea for testing purposes. Do all 6 plugs get wet when first starting? The blackish fuel mixture is 50-1 gas/oil draining from the carbs when tilted. Not unusual. The carbs drain into the bottom of the airbox and then is sucked out through the barb on the bottom of the inner airbox cover, through a hose, back into the engine under the bottom carb. A sort of "recirculation system." When you tilt the engine down to start, this mixture is sucked into the bottom cylinder-causing a very over rich condition and can lead to starting issues.

 

[HannesG]

Re: '79 235hp

Thanks emdsapmgr

You say it's not unusual for this "leaking". Do I fix this by rebuilding my carbs? I have ordered a carb kit this morning and it's going to be part of the motors' "service".

 

[HannesG]

Re: '79 235hp

And while I'm at it...

Any tips for rebuilding those carbs? Most obvisouly any tips on re-tuning them would be great!


Thanks in advance

 

[F_R]

Re: '79 235hp

Do whatever you want. But you said earlier that it runs beautifully after you get it started. That does not sound like there is anything wrong with the carbs.

 

[emdsapmgr]

Re: '79 235hp

My 79 always had the same leaking issue. Not sure if fuel flows back out of the tubes, or the carb vent when tilted. I never worried about it, as the engine started and ran just fine. F-R is right, if it runs ok when warm, then the carbs are probably OK.

 

[HannesG]

Re: '79 235hp

Well it is a very old engine and I'm not too sure if or when it has ever got this kinda treatment. I only recently purchaced the boat and would like to get everything in tip-top condition - therefor I will be fixing the little starting issues along with some other minor issues. I am also in the process of restoring the whole hull as well.


Now how bout some tips on re-tuning those carbs?


Thanks for all your comments.