1988 mercury 150 xr4 carb cleaning

[jhogue46140]

I am going to clean and rebuild the carbs and fuel pump. Boat seems to be a sluggish in take off and I don't know when this has been done last. I have a couple of questions. First when I remove the carbs, which I plan on doing one at a time, is there anything I will need to adjust once I get her all put back together. I am hoping I can take it apart clean/rebuild and put back together without having to adjust anything. I am nervous about having to adjust jets, needles, and syncing carburetors. I am not sure I will get everything adjusted correctly.

Also manual says to use carburetor cleaner. Is the spray kind from local auto store ok to use or do I need to get a special marine type. Any help will be appreciated. Thanks James.

 

[kingsnakejr]

Re: 1988 mercury 150 xr4 carb cleaning

If you rebuild the carbs,chances are you will have to add new parts and this probably will change the high and low idle settings. But if you have the manual and follow it step by step you should have no problem getting it set correctly. I use carb cleaner from the auto parts store and it works fine for me. Just remember to remove any rubber or plastic parts before soaking.
Hope this helps.
ks

 

[j_martin]

Re: 1988 mercury 150 xr4 carb cleaning

Been there, done that.

1988 XR4 has WH41 or WH41A carbs on it. There is no adjustment except linkage and the floats.

Once you've taken them apart enough to clean, just use a spray carb cleaner on them. Blow out all the passages with compressed air.

You need gasket kits when you tear them down. They are very simple carbs to work on, but you need to use new gaskets. If you don't you could get an internal leak from the float bowl to the venturi's that will drive you nuts trying to find. When you tighten down things, do it evenly. Use several passes to tighten down the bowl.

Do a formal Link n sync on it when yer done, and you should get good performance.

Hope it helps
John

 

[j_martin]

Re: 1988 mercury 150 xr4 carb cleaning

The difference between WH41 and WH41A carbs is that the A series has .048 idle jets and the base series has .052 idle jets. The A's would idle a little leaner and load up less at idle.

Just a little info to help
John

 

[jhogue46140]

Re: 1988 mercury 150 xr4 carb cleaning

Thanks all for the advice. I have the first one off and am proceeding with cleaning. I see what you mean John about not being anything to adjust. Also I think I owe you John. You have been a lot of help in all of my posts. I have worked on cars and small engines but these outboards are different beasts. I cant help much with boat questions but if you ever have any computer related issues let me know. It would be my way of paying you back. I work in IT for a career. Thanks James

 

[j_martin]

Re: 1988 mercury 150 xr4 carb cleaning

Thanks all for the advice. I have the first one off and am proceeding with cleaning. I see what you mean John about not being anything to adjust. Also I think I owe you John. You have been a lot of help in all of my posts. I have worked on cars and small engines but these outboards are different beasts. I cant help much with boat questions but if you ever have any computer related issues let me know. It would be my way of paying you back. I work in IT for a career. Thanks James

They're simpler than cars. They just go squish-bang, instead of suck-squish-bang-phart.

I might take you up on the computer thing. I work in IT also, most of the time I baffle myself.

John

 

[jhogue46140]

Re: 1988 mercury 150 xr4 carb cleaning

I have two cleaned so far and will clean the third tomorrow. So far they haven't looked bad. I am also going to rebuild the fuel pump. I hope this solves the issue. It seems to be a little sluggish when taking off and occasionally bogs down when I floor it . My top speed is about 42 mph and rpm 4300.

 

[j_martin]

Re: 1988 mercury 150 xr4 carb cleaning

I have two cleaned so far and will clean the third tomorrow. So far they haven't looked bad. I am also going to rebuild the fuel pump. I hope this solves the issue. It seems to be a little sluggish when taking off and occasionally bogs down when I floor it . My top speed is about 42 mph and rpm 4300.

What prop pitch (and type) are you running on what kind of a boat. You'll kill that engine unless you let it spin. It should be propped for over 5000 rpm. 6000 won't hurt it a bit, but it'll start to back off timing about then. It's much better overspeed than underspeed. No wonder it's bogging.

I run in the 60's with a not too light 18' bass bote, at 5800 - 6000 rpm.

hope it helps
John

 

[jhogue46140]

Re: 1988 mercury 150 xr4 carb cleaning

It is an 18 ft bass cat sabre. The prop is a stilletto. I believe the pitch is 23. I spoke with a couple of boat shops around here that sell these boats and they told me the prop was correct and the issue must be something else. Thanks

 

[hkeiner]

Re: 1988 mercury 150 xr4 carb cleaning

Basic systematic troubleshooting is your best bet as there are too many possible guesses. Do not run the motor long if all it will do is 4300 rpms.

 

[j_martin]

Re: 1988 mercury 150 xr4 carb cleaning

It is an 18 ft bass cat sabre. The prop is a stilletto. I believe the pitch is 23. I spoke with a couple of boat shops around here that sell these boats and they told me the prop was correct and the issue must be something else. Thanks

It should pull that prop to 5500 on that rig with ease. It's a 60 mph + rig. Either your boat is waterlogged, or your motor ain't hittin' on all 6.

Let's figger it out and get it fixed.

John

 

[jhogue46140]

Re: 1988 mercury 150 xr4 carb cleaning

Once I get the carbs finished and put back together I will take her back out and see how she does. I do have one question. The boat has a hot foot. I have not had much experience with these. I did notice that when I push the pedal all the way down it hits the back of the console and not the stop on the hot foot. Is there a way I can tell if the throttle is wide on when the pedal is down all the way? I wonder if this could be the issue? Thanks James

 

[j_martin]

Re: 1988 mercury 150 xr4 carb cleaning

Once I get the carbs finished and put back together I will take her back out and see how she does. I do have one question. The boat has a hot foot. I have not had much experience with these. I did notice that when I push the pedal all the way down it hits the back of the console and not the stop on the hot foot. Is there a way I can tell if the throttle is wide on when the pedal is down all the way? I wonder if this could be the issue? Thanks James

While your significant other mashes the hot foot, look down the throat of the carbs and see if they open up all the way. Don't do this on the lake, do it with the motor off. Put it in gear and mash the hotfoot.

I can't imagine installing a hot foot and not making sure it opens up all the way. duh, what is a hot foot for?

hope it helps
John

 

[jhogue46140]

Re: 1988 mercury 150 xr4 carb cleaning

I have rebuilt the fuel pump and cleaned the carbs. I am in the process of putting the carbs back together. How do I tell which carbs I have? The manual I have show WH41 and WH41A used in this model. The reason I ask is I chipped one of the idle jets when I was removing them. I ordered a new jet based on what I thought the carb was. The specs said it was a .052 jet. When I got it I noticed the hole was slightly bigger than what was installed. I looked closer and noticed the jets installed were .048. I want to make sure they are correct before I put it back together.

 

[j_martin]

Re: 1988 mercury 150 xr4 carb cleaning

WH41 has .052 idle jets. WH41A has .048. It's the only difference. .048 will run slightly richer. It'll run. They should all be the same, though.

You could drill it to .052 if yer careful. I don't think it's too critical.

My previous post was wrong. Smaller idle jets run richer, as they meter air.

hope it helps
John

 

[jhogue46140]

Re: 1988 mercury 150 xr4 carb cleaning

Hi John, Thanks for all of your help.I now have the carburetors cleaned and put back together. I have them back on the engine. I am also rebuilding fuel pump and replacing fuel lines. I will not be able to test her out until next weekend. I am on call for work this weekend until next Friday so I cant go too far. I do have a couple questions.

First, if this doesn't solve my problem where do I start next. To recap my problem is she won't go faster than 43-43 mph and tops out at about 4300 rpm at WOT. I am pretty confident she is not waterlogged. She floats on the water at the appropriate level and doesn't seem to sit too heavy on the trailer.

Second, the lake I go to only allows a 20 mph speed limit. Will this hurt the engine not running it at wide open. I am also curious as to what damage does it do with the engine not running at the correct rpm at wot and why would it hurt it. I am not questioning the information I am just trying to get a better understanding. Thanks James

 

[j_martin]

Re: 1988 mercury 150 xr4 carb cleaning

To answer the first question, Check to be sure it's hitting on all six, both on the cuffs and when it's acting up. You can do that with an induction pickup timing light, even a ten dollar one that isn't bright enough to be useful.

The linkage and timing adjustment procedure is critical. Most of the time when there are wierd problems like this, it's linkage or timing that's off. It becomes brightly apparent when doing the procedure. The procedure seems a bit intimidating at first, but it really is straight forward and step by step.

Iit's getting fuel, and hitting on all six, it would have to be not opening the throttle valves all the way, or not advancing the timing all the way. Linkage runs the throttles. Just lashing the wiring down wrong can easily jam the timing. The trigger coil and it's 7 wire harness has to move freely about 35 degrees.

On the second question, if it's running right, and prop'd right, it should run fine at part throttle without harm. In fact, as long as it's reasonably on plane it would extend engine life and maybe even improve fuel mileage. There's usually a "sweet" spot where the engine is very happy. I suspect it would be around 35 on yours. It's about 45 (out of 65) on mine.

If a motor is overprop'd so it cannot attain the design WOT engine speed, it overloads it, causing excess side loading on the pistons, and impact load on the crank and wrist pins. Remember that these are "oversquare" engines, with the bore diameter larger than the stroke. That makes the connecting rod angles pretty severe, and the piston doesn't move away from the igniting gasses very fast. That's why oversquare engines like to spin up fast. As a rule of thumb, you'll kill your motor a lot slower overrevving it than you will lugging it.

Tight lines to ya. Keep us posted
John

 

[jhogue46140]

Re: 1988 mercury 150 xr4 carb cleaning

I have the carburetors and fuel pump back on the motor. There are two electronic modules on the throttle plate that I had to disconnect to remove the plate. I am guessing they are solenoids. My manual does n0t show them. I think one is for the tilt/trim and the other for the starter. I took pictures of how it they were wired. I have hooked them back up according to the pictures. Now my tilt/trim will not work. The motor will go down but the component clicks when I hit the up button. Any thoughts. Thanks James

 

[jhogue46140]

Re: 1988 mercury 150 xr4 carb cleaning

After doing a little more research both units are solenoids for the tilt/trim. One for up and one for down. I have also discovered the issue. I stripped one of the bolts when I put it back together. It was the bolt for ground. I am ordering another unit. Thanks James

 

[j_martin]

Re: 1988 mercury 150 xr4 carb cleaning

When I got my 88 tracker 1800FS with an XR4 on it, it was a 50 mph boat, and it stumbled at WOT. I found.....

Carbs misadjusted
old rubber valves in fuel pump, and damaged
fuel filter plugged
fuel tank sludgy
Attwood primer bulb, insufficient
Attwood bayonet fittings, insufficient
Trigger harness tied down too tight (not full advance)
Needed to relieve the slot in the front of the top bearing carrier/stator mount to get the last 2 degrees of timing.
Oiler misadjusted.
Link n sync, wrong throttle pickup timing.
Lower unit, backlash and prop shaft thrust setup wrong
Lower unit, damaged seals.
Lower unit, wrong lube (you need high-perf in that one)
Water pump, damaged housing, new impeller
Engine mounted too low
Wrong propeller (2 in too shallow)

Today was one of those October days that not going fishing would be a sin akin to skipping church on Sunday. Cool weather, just me in boat, light wind chop on lake, no wakes. Went about 65 for a few rounds, turning a 24 inch high five at 6200 rpms, and that with the "advance" module on.

Keep on keeping on, you'll like the results.

John