86' 150hp Mercury XR2 Problems Previously 'boat speed question'

[jordy1380]

I wanted to start a new thread from my other thread because there were some issues getting up to speed, which turned out to be the motor not pushing enough rpms and I'm currently in the stage of figuring out this problem. Previous thread is here: http://forums.iboats.com/mercury-mariner-outboards/boat-speed-question-604568-2.html#post4222802

The last two posts by me:

I would agree that I am in the beginner stages for working on the engine. I've learned a ton about the engine already from you guys on here and just reading the repair manual. I am going to buy the OEM manual so that I have an even better idea of what I need to do to check the problems.

I checked the sparks today and it jumps the 7/16" gap just fine for the test. I did take it out on the water again today to look at the rpms and the tach again to find that it only got to 2000 rpm this time and 10mph. The wind was blowing quite a bit at 25-30 mph and there were some small white caps so I don't know if that could play any in the rpms considering the wind and waves do place pressure on the blades of the prop. After running it for about 10 minutes the rpms slowly began to climb closer to 3000 like I got it the other day, but I never got the chance to go on a straight run due to the wind and waves.

I won't have my compression tester until tuesday according to the tracking number so I won't be able to test that until then. Whats the size of ratchet to take off the spark plugs? My ratchet in my set isn't deep enough or big enough to take off the plugs. I still think that I have an issue with fuel because it seems like it would go if it had more fuel feeding into it. But I will get to cleaning the carbs soon enough Is there any cleaner that I can buy to help clean all the old grease off the engine? I have been working on that lately because it looks pretty gummed up.

I did clean some grease off of the engine and checked the fuel lines. There is a brass T that connects from the fuel line to the enricher and the fuel pump that I pulled off and cleaned that out a bit. I now have fuel that is feeding through the tube in the picture rather than it just bubbling when I pump the primer bulb. View attachment 195319

I tried this way of starting it yesterday and it still didn't start very well and sometimes it didn't start at all so I had to use my kicker. Here are the steps I tried to start it yesterday:
Prime the bulb
Turn the key on, but don't engage the starter
Hold the key down for 8-10 seconds
I don't know what you mean by 'idle arm' but mine has the normal throttle handle with a button at the base of the throttle being the override button. I push in the button and engage the throttle arm forward without actually pushing down on the throttle.
After those 4 things I tried to start it and hold it for 8-10 seconds. If it didn't pop off then I just wait another 30 seconds and try again.

Needless to say, it just didn't want to start! I checked the spark yesterday and all 6 terminals have a good spark to them, jumping a 7/16" gap no problem. I'm going to take out the plugs today to check them but I won't be able to do a compression test until I get my tools on tuesday.

Thanks in advance to all you guys that help out! Great bunch of guys!

 

[SparkieBoat]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

Well first you should check compression, if that is good check your timing. You need to remove and chunk your idle timing module and adjust your WOT timing to 24 BTDC. you need to check all linkage. you need to clean and check your carbs. check/rebuild your fuel pump. make sure all fuel line connections from tank to pump are tight and not sucking any air. make sure the pick up in your fuel tank is not clogged. make sure the air vent for your fuel tank is not clogged. Get the correct NGK plugs. my money is on the timing module.

 

[jordy1380]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

Ok, so I did a TON of cleaning the motor today. Wiping off old grease, putting on new grease. The steering case and the tilt/trim joints on the motor were super dirty. I took out the spark plugs to check them out and they were all wet with fuel and I think that they are supposed to be mostly dry?? There was also some in the threads of the plugs whether that makes a difference or not I'm not sure. All six plugs looked the same and they are model BU8H. Is that the proper one that should be used with this engine? I'm going to get all new plugs tomorrow to put them in. I took some pictures of the plugs that are in the engine currently just to have them on here so I can get an opinion. Also, I took a picture of the throttle I have because I've had a lot of guys around here ask me about a 'warm up lever' which I don't have. There are some instructions that I have posted on here that I followed to attempt to start it. I'm going to put the new plugs in tomorrow and try to start it again when I do that.

 

[SparkieBoat]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

yes that is the correct plugs. they look ok, but you never know, a cheap way to eliminate a possible problem. Does your motor still have the timing module?

 

[jordy1380]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

I replaced the plugs today which didn't make much of a difference. Still didn't want to pop off. Took a quick look at the fuel pump diaphragm and it looked fine. Is the timing module located by the oil tank on the air intake or would it be under the flywheel cover? Also, on the port side the mechanics where the gas and oil mix doesn't seem to have a gasket, could that be a problem?

 

[SparkieBoat]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

looking at your motor from the rear prop side, timing module is on your left side on top near the back. about a 5"x3" rectangle box with 3 wires coming out of it. look at a parts diagram of your motor.

 

[jordy1380]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

looking at your motor from the rear prop side, timing module is on your left side on top near the back. about a 5"x3" rectangle box with 3 wires coming out of it. look at a parts diagram of your motor.

Yeah I'm pretty sure that I have that on the motor still. Is there something I need to check on that?

 

[SparkieBoat]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

nothing to check, remove it. It was a bad idea by merc, they quit even making replacement ones and told mechanics to just chunk them and adjust WOT timing to 24 degree BTC. this part has blown a lot of motors and caused a lot of headaches, with symptoms of low power.

 

[jordy1380]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

Ok so I finally got the chance to do a cold compression test on the motor and results were not good. I didn't have time to waste trying to get it started. All cylinders met the 10% differential rule but they were only giving 74-80 PSI!! The numbers for each piston are: Right side top down- 80, 74, 74
Left side top down- 76, 74, 74

What's the next thing in line to check? All plugs spark and cylinders are in the 10% differential. Could a fuel problem cause low compression? Or is it something more complex? I have the Seloc manual and the Mercury manual but I'm about to just take the boat back to the owner considering I supposedly bought a 'working' boat.

 

[Chris1956]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

Well, with those numbers, I suspect your gauge is inaccurate. It is unlikely the wear was so even on all cylinders. I believe your compression is fine

Can you start at the beginning now? You have spark on all cylinders? What is your prop pitch? What kind of boat? Is the max spark and idle pickup timing correct?

 

[wired247]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

You do have a warm up lever. Push the button in the center and it disengages the lower unit controls. If you push the throttle forward it just makes the engine speed run up without engaging the prop.

 

[jordy1380]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

Well, with those numbers, I suspect your gauge is inaccurate. It is unlikely the wear was so even on all cylinders. I believe your compression is fine

Can you start at the beginning now? You have spark on all cylinders? What is your prop pitch? What kind of boat? Is the max spark and idle pickup timing correct?

Well, with those numbers, I suspect your gauge is inaccurate. It is unlikely the wear was so even on all cylinders. I believe your compression is fine

Can you start at the beginning now? You have spark on all cylinders? What is your prop pitch? What kind of boat? Is the max spark and idle pickup timing correct?

I just bought the gauge BRAND NEW so I don't know how that could be the problem?? I have read threads with similar results and I don't think that person ever resolved the issue. The powerhead was replaced a few years ago on that engine as reported by the servicing company. I bought this boat from a gentleman that stated it ran but when I bought it he needed to use ether to get it started. I had the same problem starting the boat and I've actually started it three times since I bought it using the fuel/oil mix. I put seafoam in the gas tank as soon as I bought the engine and since then I have put in 15 gallons of new gas. It is a 25 gallon tank as well. The prop is a 14.5"x25 ballistic which I took off and regreased the splines to check the prop shaft. There is a spark on all 6 cylinders that is an even spark and easily jumps the 7/16" gap. The boat is a 1750 Pro V Lund and I haven't done any checks on the max spark and idle pickup timing. Do I need another tool for that?

As for the 'warm up lever' you just advance that forward before you start the engine and it really hasn't made a difference in starting the motor.

Once again, this was a 'cold' compression reading if that makes much of a difference.

EDIT: Extra information to add to this thread is that it is a three blade prop and I was going 31mph at WOT with 3000-3300 rpm at WOT. It idles fine around 750rpm but doesn't push out as much rpms as it should and is really hard to actually get it started. When I pull the plugs after starting it, there is always fuel/oil mix but almost looks like more oil than fuel.

 

[jordy1380]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

Another update:

I took out the motor approx. three weeks ago and started rough, needed fuel mixture in carbs but then started up fine after the first start up. Tach showed 3000 rpms and gps showed speed at ~30mph. Took it out last Friday and was difficult to start again but rpms only got to 2000 at the most (this was going into the wind with pretty choppy waves if it matters) going 10mph according to gps. Every time I get the motor started it has no problem starting back up and takes maybe a fraction of a second when I turn the key for it to turn over and stay on.

 

[Chris1956]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

I really think your prop has too much pitch. That could hold your RPM down. The rest of the issues could be spark advance/link and synch related. I cannot think of a way for your compression to be that low and that even, based upon normal wear. Hence I suspect the gauge.

 

[jordy1380]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

Ok, well I'm going to see if the O'Rileys in town has one and borrow it to do the check. The gauge is a harbor freight so I guess it could be crap and I just looked at the reviews which state it reads low. Definitely going to take that back for my money back now! ;p My guess is since they all fall into the 10% differential that they are good as well but I am going to go through all the fuel lines from the tank to the pumps etc. to make sure that there isn't any blockage. It could be something simple like that! One question I had was in regards to the T valves that are connected to the fuel and oil lines going to the oil injector and the fuel pump. There are two male ends that go to the 90* for the main lines and a smaller male end that's about half the size. Does that smaller end only allow flow in one direction? I took it off of the line to be sure it was clean and the small male end didn't seem to pass any air through it?

 

[wired247]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

FWIW I don't think you have too much pitch. A decent running 2.0 liter 150 HP V6 should easily push a 25 pitch prop

 

[SparkieBoat]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

25 pitch prop on what boat???? I put that same motor on my Seapro SV1900 after taking it off of my 17.5 procraft. It had a 23 pitch prop which it turned fine on the procraft, but totally bogged out on my seapro, had to go all the way down to a 19 pitch prop to get over 5K RPM. The truth is there are a lot of things it could be, He would be best served to take it into a shop and let a professional outboard mechanic go over it and tell him whats up. It would be a good $100 to spend.

 

[jordy1380]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

I'm going to go with a faulty gauge because I read reviews on the one I bought and they said it read low and could be up to 40psi low. I opened the fuel filter chamber today and the screen looked fine but there was a lot of small chunks in there that settled. I haven't done a new compression test yet but I'm half tempted to take it to a shop to have them look it over. So a lower pitch prop would better service me?

 

[wired247]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

"25 pitch prop on what boat????"

The boat he said he had which is a 17 1/2 foot lund. Unles she's got the hull filled with 16 inches of water he should be able to plane that boa tup and hit 60 miles per hour with a half decent 23 to 25 pitch prop.

I'm running a 17 footer with a similar hull design and I'm hitting 60 miles per hour with a 150 horse merc and a 26 pitch prop at 6000 RPM. All my cylinders are firing and my carbs are clean.

 

[Chris1956]

Re: 86' 150hp Mercury XR2 Problems Previously 'boat speed question'

I run a 21P Rapture on my 16' Avenger (600#) speedboat with a Merc 135HPV6. I can hit 60, and thru experimentation, it appears to be the best motor/prop ombo. A 23" pitch gives a bit lower top end and hole shot. I never thought it necessary to try a larger pitch. I am with sparkie on this one....