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Mercury 150 XR2 - several ?'s

Ramifications

Ramifications

Well-known member
I'm looking for advice before I go pulling everything apart again. 1986 Mercury 150 hp XR2

I'll give you all a quick low down on the background. I bought the boat about one month ago, and it wasn't running when I purchased it. I got the engine running, and took it for a test run. The engine ran good above 1500 rpm's, but rough and sluggish below that. I thought it was the low RPM jets, so since I have pulled the carbs, thoroughly cleaned them and replaced all of the gaskets and installed new spark plugs.

In addition, due to low water pressure reading and a weak tell tale with warm to hot water coming out, I replaced the water pump, poppet valve and T-stats.

After the repairs mentioned above, I took it out for a second run. It started right up and sounded slightly better than before, but still not perfect. After pulling out of a no wake zone, I throttled up and got the same sluggish bogging down feeling until it started to turn at a higher RPM. What are your thoughts on this? Could it be the reeds?

A couple more quick questions... The cheap-o water PSI gauge that is currently in, and came with the boat, only goes to 30 psi. When running at a higher RPM, the gauge pin would be pinned. What PSI should I see at a higher RPM?

The way the engine currently sits, it leaves the prop about 5" below the pad. At WOT she would only turn about 5100 RPMs and when trimmed slightly turn about 5600 RPMs. It has a 23p prop currently. Are the low RPMs possibly tied to the other issue and/or too much prop and too low?

Any and all advice would be greatly appreciated.
 
Sounds like the prop could be a bit big. I have a 18.5 exciter and it had a xr4 150 with a 19 cleaver and it turned 5900 trimmed. New motor is 2.5 150 turning a 21 cleaver and its 5900 trimmed. with no jackplate.
 
I had that motor on the playmate. I was turning a 26p turbo 3 blade to 5100 with throttle left but ran out of balls!

Have you done a compression test?
 
Do an ohm test on you stator,it could be the low speed windings . it may be a bit of a long shot but its a free eazy test. Do you have a manual? it sahould list the readings you should get and the proceedure for testing it.
 
yellowfiero88 said:
I had that motor on the playmate. I was turning a 26p turbo 3 blade to 5100 with throttle left but ran out of balls!

Have you done a compression test?
Click to expand...

I have not done a compression test...yet. I will make sure to get one done sooner then later. I suppose all of my effort to fix things may be pointless if it is low compression, right?

Do you know what kind of water pressure I should be seeing? If it is pegging the needle over 30psi, does that mean I have a blockage somewhere?
 
ckmate225 said:
Do an ohm test on you stator,it could be the low speed windings . it may be a bit of a long shot but its a free eazy test. Do you have a manual? it sahould list the readings you should get and the proceedure for testing it.
Click to expand...

I do have an owners manual. I will check the stator and see what the readings are. I hope it is this rather than low compression!
 
ckmate225 said:
You mean a service manual, right? The owners manual will not have that info.
Click to expand...


Correct, service manual. I was sleeping on that one:sleep:

I borrowed a buddies compression gauge, so I will report back once I check the pressure and stator.

Thank you all for the advice thus far!
 
its the power pack

the good news is I had the same damned problem, same engine. I went through it, re-jetted it, thought the carb was bad...it wasn't, thought it was bad gas...it wasn't....thought it was electrical and checked all that..it wasn't...tried a different prop...wasn't that. Replaced the power pack and voila...runs like a top, great hole shot, runs at about 5700rpm all day without blinking. Good luck, its worth a look, it worked for me :bigthumb:
 
Ramifications said:
I'm looking for advice before I go pulling everything apart again. 1986 Mercury 150 hp XR2

I'll give you all a quick low down on the background. I bought the boat about one month ago, and it wasn't running when I purchased it. I got the engine running, and took it for a test run. The engine ran good above 1500 rpm's, but rough and sluggish below that. I thought it was the low RPM jets, so since I have pulled the carbs, thoroughly cleaned them and replaced all of the gaskets and installed new spark plugs.

In addition, due to low water pressure reading and a weak tell tale with warm to hot water coming out, I replaced the water pump, poppet valve and T-stats.

After the repairs mentioned above, I took it out for a second run. It started right up and sounded slightly better than before, but still not perfect. After pulling out of a no wake zone, I throttled up and got the same sluggish bogging down feeling until it started to turn at a higher RPM. What are your thoughts on this? Could it be the reeds?

A couple more quick questions... The cheap-o water PSI gauge that is currently in, and came with the boat, only goes to 30 psi. When running at a higher RPM, the gauge pin would be pinned. What PSI should I see at a higher RPM?

The way the engine currently sits, it leaves the prop about 5" below the pad. At WOT she would only turn about 5100 RPMs and when trimmed slightly turn about 5600 RPMs. It has a 23p prop currently. Are the low RPMs possibly tied to the other issue and/or too much prop and too low?

Any and all advice would be greatly appreciated.
Click to expand...


I'll try and help a bit...I have a 1987 150 XR2....But running it on a very different hull then all of you guys for prop/rpm related concerns.

First off, how is your fuel/oil consumption? I know mine loads up pretty good when idling on a cold motor. Rich on startup and needs to be pretty warm (after a nice run on plane) before the motor is real crisp coming out of the hole. After its been ran once on plain (3000-5000rpm) it jumps up pretty good and runs, I suspect dirty carbs are the culprit, or perhaps a weak fuel pump.

I have a water pressure gauge, and from all the research I've done, it seems like 3-5psi at idle, and 15ish at WFO are the 'norm' or 'recomended' well mine runs about 6-10 at idle with a strong tell tale, and 15-20 at WFO. My temp gauge also reads 3/4 hot most of the time, but I don't think its accurate. The tell tale will be hot, at least to me 120° water feels really really hot (read baby hands?), I've measured my tell tale at 125° before, I think the T-stats are somewhere around 110-115° if memory serves.

I'm running a 19pitch (14 diameter) on my 19' four winns open bow and can spin the prop 6000-6100 on the tach all day long no matter fuel, people, etc. The only thing that changes is the speed. I have a 14x17 stainless that I use for tubing/cruising with a lot of weight, and with 3 people, and a full tank of gas I can bury my 6000rpm tach like its no tomorrow. The max RPM on my 87 is listed at 6000, but a long time merc guru said the XR2's can take quite a bit more. I've ran mine following Ross for quite some time pegged at 6k with zero hiccups and a massive speed number of 45.5mph! :cheers:

I've replaced the head gaskets, and exhaust divider plate gaskets (wanted to see the condition of the cylinders/pistons the best we could) and t-stats, poppet, and water pump. The motor has about 100psi in all the cylinders but the middle one on the right side which was at about 93psi, the cylinder did look ok, and the motor is original, hours unknown. I'm going to run it til it blows, then find something different, I'm running 50:1 with oil injection removed and it seems to run much better then with the injection, it just smokes more at idle is all, but at least I know its being properly lubed.

Good luck with your motor, I've been very happy with mine.

CIMG6469.jpg

and it pushes this old hog...

CIMG6464.jpg
 
Ok, it’s been a long week at work! Actually, things have been beyond crazy since Irene passed through! Doesn't leave much time for working on the mate. In addition, I made a compromise with the wife... I get to put an addition on the garage for the mate if I close in the breezeway for her mud room/laundry room. One more thing for my list of to do's.

Moving on...My game plan for tomorrow is to run tests on everything mentioned here. Compression, stator and the power pack (if possible) I have heard two contradicting methods on the compression test. One said run the engine for a few minutes then check the compression, the other said test it cold. Which way is better?

After I check everything out, I hope to drop the lower unit and check through the water lines for any blockages. I will also run a pressure test on the lower unit since it was leaking oil from near the shifter after my last outing. Milky oil... not good! I may just drop this engine curb side and get a new one. I guess we'll have to see how things go.
 
A quick update...

I checked the compression and had 120 psi on all cylinders.

I checked the Stator and had a perfect read out on the ohms.

Any other ideas? Maybe the power pack? is there a way to test the power pack, or just replace it?

Should I pull the carbs again and clean them? while they are out I would check the reeds. I read somewhere that if the reeds are worn out you will loose power at low rpms. Can anyone verify that?

Thank you everyone for the help so far!
 
Sounds like you've got a healthy powerhead, just need to chase down the small issue. Cleaning the carbs never hurts, not sure on wore out reeds on these motors, I know I've had snowmobiles with gobs and gobs of miles on them and I think those reeds get more of a workout then the boat motors, and I've never had one fail. On sleds we just make sure we can't see much light between the petals when they are closed...
 
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