Back to the drawing board

1995 175 evinrude intruder. Alright get one thing kind of solved and now i have another issue. I'm not getting the rpm's i used to get. Motor was running about 5600 wot. Now if i trim it out to the max it might be getting 5100 to 5200. Lost about 7 or 8 mph also somewhere. Pulled the spark plugs and 1-5 all looked like they should, almost lean looking though, but they do have a light tan tint and they're not white crusted. Anway i pull number 6 and the diode is almost black, maybe one small section of diode that isn't black. Earlier in the year my gps read 64 at 5600, now 5100 or 5200 at 56 mph. Only plug with any noticeable difference from the other is number 6, but i can pull the plug in the drive and you can still tell a difference, though. Dang thing lean sneezed again today and the primer bulb was hard as a brick.

So in short the motor has lost some top end and rpm and number six plug is almost black on 75 percent of the diode. Coil breaking down at high speed? Is the plug baking? Causing it to turn black.? Is number 6 getting hotter than the others? Clogged or malfunctioning check valves? Primer bulb is staying hard and it still lean sneezed, Could it possibly be high speed orfice in number 6 clogged?

Re: Back to the drawing board

Bump.... I'm still all ears. I'm guessing i'm losing a cylinder at high speed anyone agree? 7, 8 mph and about 500 rpm sounds about like a cylinder doesn't it.

Re: Back to the drawing board

It is hard to guess what the loss of a cylinder would do. Did you take a baseline compression test? You should take a compression test now and see if you have a low cylinder. Check the carb to the black plug and see if it is floodiing. Put a timing light on the black plug and see if you have spark.

Re: Back to the drawing board

I just took a compression test here are the results.
1) 103 or 104
2)103 or 104
3)101 or 102
4) 101 or 102
5)97 or 98
6)95 is it.

I doubt this motor has had a decarb in quite sometime, probably more than 50 hours probably more like a 100 or never. Compression guage i have is ten years old. Number 6 is the lowest one though. They're within ten percent but just barely. Probably decarb it and that cylinder would come up a little maybe. I took the number 6 carb off.... checked float height that looks good.

Whats a good way to test if the needle valve is sealing or not? Its brand new and i know its not pitted or wore out yet.

Well i'm thinking check valves, i can't see how those would foul out a plug. I guess if one was faulty it could send too much mix to the cylinder. I've blew through them toward the motor and i got no air. I tested them last year with the bubbles in the water trick.

Re: Back to the drawing board

Bump.

Re: Back to the drawing board

None of your cylinders have any decent compression. I hope the gauge is inaccurate. Anyway, you might do a decarb and put a timing light on #6 to check for eratic spark. Repost the compression, or get a known reliable gauge. If your compresion numbers are really that low, you likely have a tired engine.

BTW - I ran the RPM and MPH numbers you provided thru a prop calculator. They do not coorelate. if your speed at 5200 RPM is 56MPH, the speed at 5600 would be 60MPH, with the same prop. BTW - both these speeds are pretty unusual for the average boat to make with this kind of power. What hull are you running?

Re: Back to the drawing board

Maybe, but i've also heard big loopers read low like that. Two shops in the past year have both told me the numbers were fine. Like i said my guage is old and i doubt this thing has had a decarb done in forever. Might be just a tired old motor, but guys on here have told me those numbers were fine. Number 6 worrys me though. Float drop on number 6 was off though. I don't know how critical that is but might be it, maybe not. I'm about to the point where i'm not going to do to much more to this motor. Just run it the rest of the year and unload it in the offseason. I'm going back to merc, i can't stand these looper motors. Etec might be good, but this looper has ruined any opinion i could have formed for evinrude, since this is the only one i've owned. The experience hasn't been pleasant and its been costly.

The boat i'm running is a 18' 5" 95 hydrasport. I really like the boat, setup is nice and plenty of storage, rod locker could use some work. I've clocked my gps at 63 mph, which i figure is about right for this rig. I had a mechanic adjust my idle screws to get this thing to stop bogging out of the hole. Well we accomplished that pretty well. But now i get the wet plug on 6, its black and the power is down. One guy told me its black from lack of gas, that just doesn't sound right.

Re: Back to the drawing board

Current owner of two 150 1995 loopers. Htey both run like a scalded dog! Dont diss the motors, the loopers like the fuel but they are very reliable.

The compression seems OK to me. You know it needs a decarb and the compression numbers will come up. Possible stuck ring?

Stuck or non closing float on #6? Test by removing and inverting. Blow air thru fuel input. No air should go through. It should blow through fine. Turn right side up. No air should go through.

Black plug indicates it's firing, no fire and it would be wet. I'd test the spark as Chris recommended. Check for erratic firing and spark gap jump. It is important that it can jump 1/2 inch and it's strong and blue.

Have you had the carbs rebuilt? A plugged main vent could cause this rich at WOT condition.

You said you solved a previous problem and now this ones cropped up. What was the previous problem?

Re: Back to the drawing board

Fl_Richard said:

Current owner of two 150 1995 loopers. Htey both run like a scalded dog! Dont diss the motors, the loopers like the fuel but they are very reliable.

The compression seems OK to me. You know it needs a decarb and the compression numbers will come up. Possible stuck ring?

Stuck or non closing float on #6? Test by removing and inverting. Blow air thru fuel input. It should blow through fine. Turn right side up. No air should go through.

Black plug indicates it's firing, no fire and it would be wet. I'd test the spark as Chris recommended. Check for erratic firing and spark gap jump. It is important that it can jump 1/2 inch and it's strong and blue.

Have you had the carbs rebuilt? A plugged main vent could cause this rich at WOT condition.

You said you solved a previous problem and now this ones cropped up. What was the previous problem?

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The previous problem was a lean sneeze at low idle and bogging when trying to come out of the hole. You would have to feather the carb to get it to get on plain, but only after the motor had warmed up. Seemed to happen more the longer you sat somewhere say thirty minutes or better.

Would a float having too much drop cause the float needle to not close all the way?

Re: Back to the drawing board

The lower compression and darker plug color on the same cylinder is an indication that the cylinder is on it's way out. Try to look into the cylinder with a mirror and light to see if the walls are showing signs of scoring.

The float drop lower than spec will mean less fuel in the bowl. Could be that the cylinder has been running lean for a while and now is loosing compression resulting in an incomplete burning of the fuel and showing the black on the plug.

Next compression test spray some oil in the cylinder and check it again.

BTW: carb upside down should not allow air flow, right side up, float drops: air flow.

Swap the plugs in the cylinders and check them again after a couple of days running.

Good Luck,
Capt Ron

Re: Back to the drawing board

Its never read higher than 95 the whole time i've had it. The cylinder walls look good, might be a stuck ring. I think i'm going to run that can of engine tuner through it.

Re: Back to the drawing board

I hope that I didn't come off too strong earlier, all the shops that I worked in always had rules about the correct troubleshooting flow that began with the compression. The readings that you posted would be a stop point until the owner was notified and authorized any further work.

The mechanical aspects of the motor have to be up to par before wasting time with carburation or electrical issues. Speaking of electrical, run the engine in the dark, as dark as you can get, and look at all the wiring, especially the high voltage wires. A glow from the plug wires will indicate a high voltage leak, it doesn't take much to affect performance.

Good Luck,
Capt Ron

Re: Back to the drawing board

Capt Ron said:

I hope that I didn't come off too strong earlier, all the shops that I worked in always had rules about the correct troubleshooting flow that began with the compression. The readings that you posted would be a stop point until the owner was notified and authorized any further work.

The mechanical aspects of the motor have to be up to par before wasting time with carburation or electrical issues. Speaking of electrical, run the engine in the dark, as dark as you can get, and look at all the wiring, especially the high voltage wires. A glow from the plug wires will indicate a high voltage leak, it doesn't take much to affect performance.

Good Luck,
Capt Ron

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Two seperate shops have both ran compression tests on the motor and both said the readings were fine. Both shops... licensed OMC dealers. I can get a new block and the psi readings would be somewhere around 115-120 on a looper motor and thats on the high end of things. The big loopers run a softer head gasket resulting in lower compression numbers. My guage is old and i get the feeling its off by a few psi. The readings are still within the 10 to 15 percent range anyway.

I pulled all of my carbs. My manual said the float drop should be between 11/16 and 1 1/8. Everyone of mine was around 1 3/8. They were all low. I'm trying right now to get a hold of the idiot that put the kits in. The motor has been starving for fuel. Still doesn't explain why one plug was damn near black and the rest were kind of lean looking. I'm probably lucky the motor didn't blow up. It has the overheat warning and slow feature on it. Neither have ever went off except when i chunked the gears out of the lower unit.

Re: Back to the drawing board

Hello
I am having the same problem with my 225 looper, bogging, starting problems and black dry spark plug except mine is no. 2. Im suspecting (hoping!) it is an over fueling problem. thats what it feels like.

Anyway back to your problem, being that it is your no. 6 plug which is fouling, assuming the carb is ok. There is a good possibiliy that you have a fault with your VRO pump. The no. 6 cylinder is used to operate the diaphram in the pump to suck up the fuel and oil. If the diaphram has a small hole in it, it will still work but would allow unwated fuel to be sucked into the no.6 cylinder resulting in the fouled plug. The hole would also cause the pump to run less efficient causing a slight loss of power (rpm's) and thus less top speed. All these tally up with your fault. Please let us know if you find anything.

John