older Mercury 115 will idle but will not go past about 1500 rpm's

Ricnc123 · #1 January 24th, 2006, 10:06 AM

I've got an older, straight six cylinder 115 Mercury on an Ebbtide fish and ski. The motor starts without too much trouble, even after setting most of the Fall and Winter, but the last few times out, including last Summer, the boat does not want to run after I put it in gear. I've put new plugs, checked the compression, and still having this problem. Can anyone help me on this?

andy6374 · #2 January 24th, 2006, 10:15 AM

Some serious miscarriage of info here...Deleted!!

Ricnc123 · #3 January 24th, 2006, 10:27 AM

Does spun prop mean there is something stripped in the lower unit?

DOCD9501 · #4 January 24th, 2006, 10:28 AM

It dies when you put it in gear? Will it rev up in nuetral? You could have carb issues. Or a friend of mine had the same problem and a bent drive shaft was his problem. It would idle fine but when you put it in gear it croaked! Mech found the d shaft was bent. Good luck.

LubeDude · #5 January 24th, 2006, 10:31 AM

Quote:

Originally posted by andy6374:

My first guess is a spun prop.

WHAT????

If it was a spun prop hub it would over rev, not under rev!!

As a guess, I would think maybe a week fuel pump. Have someone pump the bulb while you try and accelerate.

Ricnc123 · #6 January 24th, 2006, 10:31 AM

Yes, it revs good in neutral. I would rather it be carb issues than a bent shaft. Although, I did notice lower gear unit oil coming out around the prop when I ran it.

Ricnc123 · #7 January 24th, 2006, 10:37 AM

I checked the the primer bulb, it seems to stay pretty hard, but I'm not sure it's as hard as it's supposed to be. I tightened the screw clamps around it. How can I check for a weak fuel pump? I checked and it seems to be clean and in good shape.

Ricnc123 · #8 January 24th, 2006, 10:38 AM

It will die if I try to go past about 1500 rpm in gear, but will rev in neutral.

Ricnc123 · #9 January 24th, 2006, 10:54 AM

Thanks for all the advise. It was very helpful.

andy6374 · #10 January 24th, 2006, 11:21 AM

Sorry Merky, I totally misinterpeted what you wrote and its not like what you wrote was complicated. I not sure what was going through my mind

.

It's not a spun prop, THAT'S WRONG!!!

Everyone else was pointing you in the right direction...fuel pump / carbs.

To test the fuel pump, have someone pump the primer bulb while giving it throttle and if this saves the engine from stalling or bogging then you will need to rebuild the fuel pump.

Once again sorry

andy6374 · #11 January 24th, 2006, 11:27 AM

To answer your question:

A spun prop is when the inner hub of the propeller gets damaged to the point that it is no longer "connected" to the outer propeller shell. So the propshaft will spin and so will the prop hub, but the prop will remain motionless.

This can also happen on an intermediate basis as well. EX, the motor will have thrust between 650-1500 RPM's and then anything higher will cause the prop not to spin.

Ricnc123 · #12 January 24th, 2006, 04:24 PM

Thanks very much for the advise. Hopefully this will help someone else, too.

mercerfisherman · #13 January 24th, 2006, 04:37 PM

I'm not an outboard expert so I don't know how your problem compares to the one I had. But, I had a similar situation with my 50 hp Merc. It would start and idle but wouldn't run when shifted into gear. It turned out to be a "switch box." Once they replaced it, it ran good. Good luck.

Rob Isaacs · #14 January 25th, 2006, 12:36 AM

Rick is the engine running on all cyl. It could only be running on five. Also choke briefly before engaging fwrd gear. Does this help??? Was there any water on plugs when you checked them (Thinking you may have a water jacket leaking)

Need more info.

Clams Canino · #15 January 25th, 2006, 03:29 AM

Mewrky, what year is this critter? Distributor or ADI ignition?

-W

timmathis · #16 January 25th, 2006, 07:58 AM

This could be a distributor or timing issue.

phatmanmike · #17 January 25th, 2006, 12:30 PM

check your cowl hood. how is it, is it tight, it could be loose or missing snap or lock on the hood.

just kidding. you got the attention of tim and clams now, consider it solved.

timmathis · #18 January 25th, 2006, 05:22 PM

Myoutboards, You better hang around! I don't know about clams but I'm going to be covered up for the next few weeks and will not have much time to help. I'll be glad to if I have any time.

BTW. You have forgotten more than I will ever know about outboards. I'm still in training from you pro's. Have a good one, Tim

emckelvy · #19 January 26th, 2006, 02:51 PM

If it's a non-distributor motor, very likely the hi-speed windings in the stator are burnt out. It'll still start and idle (albeit perhaps poorly), but won't develop any power. Resistance check of the stator windings will tell all.

Nos4r2 · #20 January 26th, 2006, 03:07 PM

Just a thought-you didn't say you'd cleaned the floatbowls out. Someone jump on me with a big hammer if I'm wrong- but have you recently run seafoam or redex in the gas? I found that the stuff does it's job so well that it can cause any scale in the carbs to come off and block your main jets.

timmathis · #21 January 27th, 2006, 07:17 AM

Mewrky, what year is this critter? Distributor or ADI ignition?