power loss V150

[RiverRatMD]

Engine: 1982 Mercury V-150 (2.0L 150 HP V6)
Ser# 6132261

So I have this engine running now, and it was running very good. I have re-built the carbs and completely gone through the fuel system....rebuilt the pump...replaced all the fuel lines and bleeder lines.....Installed CC Reeds and replaced just about every gasket in this thing.

I was able to get my Heavy ProCraft into the low 50's with it which is just fine., However, a new Gremlin. I was at a 4 day outing, engine was great....then day 4 I was cruising and then went from 50 to 39/40 and could not get anymore and the holeshot is terrible now...before it jumped right up.

Now I can't get over 41.7 and I can FEEL the Power try to surge then bog try to go then bog when holding throttle WOT...if I back off to say 3/4 it runs fine but feels flat....I can hold 41 mph all day at WOT...but nothing more. I have replaced the rectifier and switch boxes also....The only thing I have not done is a stator. Feels like the high speed windings are possibly going out? I even pulled the carbs and went through them again...no change. I tried multiple Props...They all run about the same....the power loss at the top has equalized all props...lol....

What to do, what to do?

Rat

[JOE54]

check compression ,check compression ,check spark ,check spark

[EuropeanAM]

And if both are perfect: Connect a separate portable fuel tank, with it's OWN line and bulb to your engine to see if the problem remains or ceases.

[RiverRatMD]

UPDATE:

Compression - 125 across the board (Thank ya Lord)
Spark - Good and snappy

Now the odd and embarrassing part : I picked up a new fuel pump assy (mine was pretty rusty and corroded inside when I first re-built it) anyways, this new used one came and I took it apart to rebuild it.....Well....There was an extra gasket in the new one that was not in the first one I re-built. Without a manual I rebuilt the first one as it came apart....The newer one had the rubber diaphragm sandwiched between two gaskets....When I re-built the first one, I only put a gasket on the outside.

This likely made for a lot of loose pump action without the benefit of the inside gasket keeping that diaphragm taunt in the housing? Thus making the pump not able to keep up with the demands of fuel needed at WOT?? i can not test this until a day or two when I can get to the water. My question is....Why did it take about 2 hours of operation driving the boat to begin finally starving for fuel without this gasket? I hope I am gonna find a ton of extra performance after this....OMG, this old Vert reed Merc is giving me the blues!

[RiverRatMD]

check compression ,check compression ,check spark ,check spark

[JOE54]

RAT i dont think its solved. those older v6 engines did not have a filter between pump and carbs if a piece of gasket is lodged in a seat it will restrict fuel flow to one cylinder, been there seen that bud , make sure spring and cap are in pump also to keep diaphram tight , you did check tuner right ???? and no water evidence on plugs the divider plate gaskets will blow some at high rpm through exh ports .... hurry up they're bittn ....JOE

[RiverRatMD]

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Gasket #28....There are 2. One on each side of the rubber diaphragm that the spring and cap are pushing on(inside fuel pump assy)....Only 1 gasket was installed...the outer one. The inside (first one) was not installed....so that would likely not allow the diaphragm to be tight....i am thinking....And correct, there is no filter.....all seats are clear. NO water on the plugs,,,,both divider plate gaskets were replaced......no, did not check tuner

and Don, when I go check this out, I will take a separate tank, lines and bulb as well to try...After I see if this was it

[JOE54]

and a timing light

[RiverRatMD]

Okay....Back to "very good" power! It was the missing gasket in the fuel pump....So THAT little Gremlin of bogging and "I wanna go/I don't wanna go" syndrome is gone and the Hole shot is MUCH better.....

On to, well, I can't leave well enough alone.....Joe, you said Timing light....SO, I removed the idle stabilizer module, grounded all my wires, and went about checking WOT while at cranking speed.....IT was 15 BTC....I set it to 18 BTC and left the idle stabilizer box OFF (it was all soft and gooey in the back)....From what I can remember messing with the 2.0 - 2.5L V-6 Mercs in the past....These boxes caused more problems than they corrected at times.... Any harm in leaving it off with 18 BTC timing on this V150?

[JOE54]

no harm at all , id run it at 20

[RiverRatMD]

Awesome Joe thanks! I will set it to 20....I wanna run this motor to at least 5800 when I prop it. I will be putting some serious run-time on this engine over the next 2 months, so I hope the Gremlins are in a holding pattern. Take er easy till the next time....

[JOE54]

yes sir your welcome

[RiverRatMD]

OK Joe, got to thinking (bad as that may be)...If i am gonna set my timing to 20 btc....I might as well let you know my pick up is set to 4 ATC...is that fine or do you have a better mark in mind? FYI, I am also running BU8H

[JOE54]

pick up doesnt efect max timing so its fine there

[RiverRatMD]

Joe, still working out the final Gremlins on this thing.....Here is the latest: 2 trips out since I deemed this engine fixed....

Trip 1: 6 days ago. Went out with my known good 23P Lazer 2. Made two speed runs - awesome holeshot --In the first run I ran 55 at 5600 rpms (not quite everything it had, but was very happy with this test run near WOT and full trim). Second run - I hit 57 at 6000 RPM's and smelled something electrical burning (you know that smell)....I stopped immediately, noticed the TACH turned WHITE! Smoke came out from under the dash and I dove back and disconnected ALL the POS+ wires off the battery....The quicksilver TACH shorted out and took out the Main fuse at the engine!!! Holy crap I had a fire gremlin this time!

What I did: I inspected and tested the wiring, the rectifier, the stator and wires, all grounds, ect.... I installed my known good original tach, replaced the fuse and deemed the quicksilver tach simply for some reason "shorted-out"

TRIP 2: 2 days ago. Installed my very good Tempest 23 (got lots of props). This time ran 53 at a max of 5400 rpms but it ran ALL DAY absolutely flawless...Strong, snappy, just not as many RPMs and a little slower with a decent holeshot. But the point is, I ran it HARD all day long and for long stretches too....

my question(s): I would prefer to run the Lazer 2 @ 6000 Rpms with more top end and better holeshot....But should I be afraid of 6000 RPM's?? I think the tach just shorted out on its own and simple as that, but damn, everytime I hit 6000 R's something seems to happen...That is either coincidence or something weird is happening at 6000 Rpms!!??!? Your thoughts?

[JOE54]

RAT i feel the 23 TEMPEST may be a lil big for that 2.0L engine , you got a 21 TEMPEST ???? what does prop to pad look like , remember when it gets hot it gonna come down in power so less RPM , that engine came with metal cage rod bearings i wouldnt sweat 6K at all and have run um many miles at that sometimes hundred a day , when you get it all set up we may play with a jet or two or six ps ; i know where there is some more parts for that engine probly cheap

[EuropeanAM]

+1 to Joe's suggestions ^^^. I'd rather see that engine at 5800-6000 so the best option would be a 21P Tempest (or switch back to your Laser 2, as an alternate resort). Not particularly fond of the Laser series... they were great for their day but I think you're leaving some performance in the wake.

[RiverRatMD]

ENGINE UPDATE: JOE!! Okay I took her out today and she ran FLAWLESSLY! Not a hint of bog or power loss. Crisp and smooth. Humidity was higher today and it was windy so I only had a mile of river to work with.

The Numbers: ProCraft 180 Dual Pro (1650 lbs) & Lazer2 23P stock but very good condition and no jackplate. 54-55.7 mph at 5900 Rpm's. (tidal water so mph will always be + or - 1.5 mph depending how I am running the tide. Killer holeshot. very good acceleration. Therefore Joe, I again deem this engine.....SET UP and running excellent.

My buddy has a good 21P Tempest I will try when I get a chance. I also have a 23P Trophy Plus in fair shape to try....I mean, why not right?
My goal all along with this boat (My back-up Bass boat, I've had her 28 years now) has been to be a fully functional backup that can run low to mid 50's and be dependable.
That said....I do love to tinker....Although, I won't put a JP on this boat. I had a JP on her long ago with a 175Xri...She ran 66 mph with a Robbie P built 26 Tempest when Lee was in Richmond.....Ran that until I blew out the transom...Had Transom and knee braces all re-built....So I am gonna be good to this one. But I would like to go as fast as can without one.

BIG THANK YOU to you Joe!! You have been incredibly helpful.....And of course you too Don...Thanks guys, for all you do

Rat

[JOE54]

man that TEMPEST aughta get the nose up and speed up too , id have to try a 6 in plate on it just to get it exact height then let it roll ,,,, anytime RAT its what we do