Sputtering 83 Evinrude 150.

[Greg_Cornish]

My 150 started getting harder and harder to rev up even in neutral. I took it home, put the hose and rabbit ears on it , then cleaned out the oil filter sized inline fuel strainer and poured the gas in a glass jar. About a thimble full of water was on the bottom. I reinstalled it, pumped up the bulb and it popped right off. I went into gear and revved up perfectly.

Excited I backed it into the lake and started it up. With back pressure on the exhaust it wouldn't rev. It won't stay running even though out of the water I set the idle to 1100 RPM.

I took it home, put the hose on and again it ran fine. Anyone ever have a similar problem?

[David Rogers]

Hey Greg,

Yes I have with my 1986 175 Merc, it takes more RPMS to push the water through the intakes than with just the rabit ears so you will have to increase the rpm even more, with the hose you have applied water presure, in the lake, its all up to the water pump. I don't know about your motor but my motors compression is off by 25 lbs, for example one piston has 100 lbs and one has 125 lbs, a top of the line shop says when you have over 25 lbs of presure dif in your cylindars you will not have a good Idle and have to increase it more and more unit it will idle while in the lake. If you were fine before you may want to have your compression checked to make sure there is not a worse problem going on so you don't cause more damage.

I know you know what BOAT stands for! (Bust Out Another Thousand)

[Greg_Cornish]

Hey Greg,

I don't know about your motor but my motors compression is off by 25 lbs, for example one piston has 100 lbs and one has 125 lbs, a top of the line shop says when you have over 25 lbs of presure dif in your cylinders you will not have a good Idle and have to increase it more and more unit it will idle while in the lake. If you were fine before you may want to have your compression checked to make sure there is not a worse problem going on so you don't cause more damage.

I know you know what BOAT stands for! (Bust Out Another Thousand)

My boat was checked 3 running hours ago and has 3 pounds differentiation between all 6 cylinders. However it won't come up to 5500 rpm even when in neutral.

[David Rogers]

Hi Greg,

That thing sure pure like a kitten at 800-900 rpm with those comp readings. Time to take her to a pro or semi pro:)

Our boat can be our best friend and our worst enemy:)

Let me know what you find out, the more info we have the more money we can save in the future.

[Greg_Cornish]

Hi Greg,

That thing sure pure like a kitten at 800-900 rpm with those comp readings. Time to take her to a pro or semi pro:)

Our boat can be our best friend and our worst enemy:)

Let me know what you find out, the more info we have the more money we can save in the future.

I will, I can't get in to see him until the end of the week.

[thejerbs]

Revving your engine that high when not underload isn't very good for it.

That seems like an awful lot of water. Have you ever checked out the iboats.com forums greg? There is a ton of useful info on those, along with free advice from people who "usually" know what they are talking about.

I have a 1988 black max 175 and it started bogging out I changed the water separator and made sure my vent line was clear. It runs like a champ now.

[Greg_Cornish]

I didn't rev it that high.

[Greg_Cornish]

Changed plugs. Started it up again on the hose, ran great. Took it to the water and backed it in far enough to cover water intakes. Still ran great. Backed it into the water so the boat was horizontal and it wouldn't even idle. The coincidence is the boat is at an angle not unlike a boat ramp parked at home too. I'm going to inspect all fuel lines to see if they are sucking air tomorrow and replace all rubber lines, needed or not.

[Greg_Cornish]

Okay, I found something new today.

We put it in the water today with the same results. The guy that we had along that used to work on his own of the very same kind, pulled the cover and flipped a fuel regulator lever and it ran better. I haven't been shown what that was yet. However soon it was back to its same tricks. He found 6 lose hose clamps going to the fuel pumps that were loose and tightened those, I suppose a lot of things vibrated loose with the old lower unit. Then there were some vacuum lines that the Cable ties had fallen off and they were sucking air. We replaced those with hose clamps.

After we corrected all those thing we took it out and it ran great. However when we lowered the engine completely we found it still ran rough and killed. I got out of the boat at the dock and watched as they raised and lowered the engine. There are 2 ports on the rear of the engine as my illustration shows. Both exhaust and water shoots out of them above the water line. As the engine is tilted up so these holes are above the water line the engine runs perfectly. We took it out and ran it up and it performed well, however at that angle it cavitates, so I need to lower the engine all the way while on plane. When I'm on plane the boat is far enough out of water that it still runs just fine. However when it comes to a stop I have to adjust it up so it won't kill .

When the engine is down and the water is above those ports the engine, it will not idle no matter what the idle speed. Do you think a drain down compression check is in order?

I can get along with it running like this now that I know what is going on. However, what should I do for the long run? Is this normal? Is it something that should be fixed? I've always wondered why it killed backing up, now I know, it was flooding those exhaust ports. If I tilt the engine up, I can back up now.

[SHAFT]

Try posting your problem here , I have always had good luck with these guys .

http://bbcboards.zeroforum.com/zeroforum?id=51

[Greg_Cornish]

Try posting your problem here , I have always had good luck with these guys .

http://bbcboards.zeroforum.com/zeroforum?id=51

Thanks for the tip. I took your advice. Looks like the right place.

[Phil]

GREG;
I just went thru all this crap on my 1989 Evenrude 150XP. Finally runs like a top, and finally starts well.......I suggest call Greg in the shop at Lake Don Pedro Marina..209-852-2369, he is the expert over here . We wound up putting new brain box in mine !!

JIGS

[David Rogers]

Hey Greg,

I love your illustrations!!! You do not want your boat sitting so low in the water that it covers your exhaust outlets, even if your boat is running perfect I would think that would stall your boat, think about a truck when you back your boat in the water, if you back your truck to far in with our tail pipe under water, eventully your truck will stall, the compression can not handle pushing the water out to keep firing.

[Greg_Cornish]

Hey Greg,

I love your illustrations!!! You do not want your boat sitting so low in the water that it covers your exhaust outlets, even if your boat is running perfect I would think that would stall your boat, think about a truck when you back your boat in the water, if you back your truck to far in with our tail pipe under water, eventully your truck will stall, the compression can not handle pushing the water out to keep firing.

I called the guy Jigs recommended and he confirmed that.

[TonyL]

So if I've been following correctly,sounds like your engine is just fine and you actually have a cavitation problem ? Start after the new/used lower unit, any weight shifting,rearrangeing cargo in the boat?

[Greg_Cornish]

So if I've been following correctly,sounds like your engine is just fine and you actually have a cavitation problem ? Start after the new/used lower unit, any weight shifting,rearrangeing cargo in the boat?

The only difference was that the lower unit that came with the 150 was a light duty for a 120 hp motor and the one I have now is for a heavy duty 150. It might have lowered the rear by 1 inch., not sure

[GW]

Greg,

A jackplate would solve that. I bet you would be the only pontoon on the lake with a jack plate...........

[Greg_Cornish]

I could buy another pontoon for the price of a jack plate right?

[Guyle]

Sounds like you got Quaggas in there.

[GW]

you could buy a new boat but you would not look as cool

[Rod Martin]

How about mounting holes on the motor can it be raised into a lower set of holes. Dont know rudes, but mercs have 4 or 5 set of mounting holes. Also if you have been running it this way, it may have carbon buildup.

[Greg_Cornish]

How about mounting holes on the motor can it be raised into a lower set of holes.

I have experimented like crazy with those holes. One down is 5 mph less, 1 up it cavitates. Now that I realize the problem I can deal with it.