Evinrude XP150 not accelerating

[MASTER Brian]

I have a 1986 Evinrude XP150. Last weekend there were a few times when it didn't seem to have good power, but then a bit later or after mashing the throttle for a second, it would seem to clear out and run fine.<br /><br />I was hoping it was a dirty water/fuel seperator, so I changed that, but today, after running for about an hour and shutting it off, it started right up, but wouldn't accelerate over an idle speed. <br /><br />It seems to be getting good fuel after the VRO pump. I checked compression when I got home and 5 of the 6 cylinders where all between about 82-88 PSI, the bottom passanger cylinder was only about 55 psi. I'm guessing I have a stuck ring, does that sound about right?? <br /><br />All the plugs where blackish, so it appears they are getting good oil and from what I could see with a flashlight the piston tops didn't look pitted, which is what I've seen when a motor runs lean.<br /><br />If I take this in, what am I looking at cost wise? If I do the work myself, is there somewhere I can get a manual and where is the best place to get the parts? I've rebuilt several 2-stroke 2cylinder jetski motors, so I have some background with 2-strokes, but outboards are new to me. What would you recommend doing if there isn't major damage...rings, pistons and a hone/bore??<br /><br />What compression should this motor have?

 

[MASTER Brian]

Re: Evinrude XP150 not accelerating

A bit more history on this after reading some other threads...<br /><br />The primer bulb feels pretty solid prior to starting, didn't try pumping it when the boat wouldn't run at speed. <br /><br />When I say the VRO seems to be working fine, it would pulse fuel out in big spurts, with the hose unhooked directly after the pump, prior to the carbs. <br /><br />Also, I took these compression readings after towing the boat home, so the motor was cold. Boat still idles great and starts right up.<br /><br />Thanks...

 

[sikpnter]

Re: Evinrude XP150 not accelerating

Do a decarb on this motor to see if that cyl comes back up.

 

[emdsapmgr]

Re: Evinrude XP150 not accelerating

You may have a scuffed piston on one hole. Try looking through the plug hole on the bad cylinder. You may have to take the head off on that side and see what is going on. You can also pull the side cover off that hole and check out the piston skirt for carbon or scuffing. That engine should run 90 lbs compression. Be sure to check the compression with all plugs out. See how bad it it before estimating overhaul. sikpnter offers a good idea.

 

[MASTER Brian]

Re: Evinrude XP150 not accelerating

How do I do a decarb?<br /><br />I don't want to do an overhaul. I will recheck the compression with all the plugs out, when I checked it, I only had the plug out on the cylinder I was checking. On a jetski I am told to ground the plug, so that I don't fry a coil, does that not matter on an outboard? One person said it didn't...but I wasn't sure, so I grounded the plug.<br /><br />Also, I am using a fairly new snap-on gauge, so I am sure it is accurate, if anyone questions that.

 

[MASTER Brian]

Re: Evinrude XP150 not accelerating

After thinking a bit about this, I don't see why, even with one cylinder not having great compression, it wouldn't run faster than an idle. Would one cylinder running 30psi lower cause a V-6 not to run over an idle??

 

[beau123]

Re: Evinrude XP150 not accelerating

Go to Engine FAQ for decarbing, there is a really good explaination on how to decarb.

 

[wilde1j]

Re: Evinrude XP150 not accelerating

Originally posted by MASTER Brian:<br /> After thinking a bit about this, I don't see why, even with one cylinder not having great compression, it wouldn't run faster than an idle. Would one cylinder running 30psi lower cause a V-6 not to run over an idle??

No, something else is going on. Fuel starvation is the most likely ... try pumping primer bulb or activating choke or primer combined with WOT and let us know result.<br /><br />Decarb may help the low cylinder, but that's not what's keeping it at idle rpm.<br /><br />I would try to get an OEM shop manual ... try Ebay or other sites such as Ken Cook, etc.

 

[MASTER Brian]

Re: Evinrude XP150 not accelerating

That's what I've been looking for, wonder why it didn't pull up in a search.<br /><br />Thanks!!

 

[MASTER Brian]

Re: Evinrude XP150 not accelerating

Originally posted by WildeOne:<br />

Originally posted by MASTER Brian:<br /> After thinking a bit about this, I don't see why, even with one cylinder not having great compression, it wouldn't run faster than an idle. Would one cylinder running 30psi lower cause a V-6 not to run over an idle??

No, something else is going on. Fuel starvation is the most likely ... try pumping primer bulb or activating choke or primer combined with WOT and let us know result.<br /><br />Decarb may help the low cylinder, but that's not what's keeping it at idle rpm.<br /><br />I would try to get an OEM shop manual ... try Ebay or other sites such as Ken Cook, etc.

I'll try the decarb as well as the primer bulb. <br /><br />I'd think fuel starvation as well, but can't figure out why. Like I mentioned the pump shoots gas in spurts, which I associate to the pulse of the engine. I have the air cleaner off, so I will look to see if I can tell if its getting gas to the carbs. Maybe some carb cleaner will clear the carbs out.

 

[wilde1j]

Re: Evinrude XP150 not accelerating

Carbs get cleaned by disassembly, soaking in carb cleaner and blowing clean with air. Can't clean them from outside. Just idle rpm is something else though.

 

[sikpnter]

Re: Evinrude XP150 not accelerating

Someone please correct me if Im wrong but if I understood him right he is saying that bottom port cylinder is at 55psi which is way low, the vro runs off this cylinder, if its leaking the vro wont function properly. Right?

 

[MASTER Brian]

Re: Evinrude XP150 not accelerating

Originally posted by sikpnter:<br /> Someone please correct me if Im wrong but if I understood him right he is saying that bottom port cylinder is at 55psi which is way low, the vro runs off this cylinder, if its leaking the vro wont function properly. Right?

That is interesting. That would make some sense to me at this point.<br /><br />I did the decarb and that didn't seem to make any difference. I was only able to do the first run and part of a second one, before I ran out of gas in the tank. I did have another can of sea foam, so I dumped it in one of my fuel tanks and tried a few runs, but still nothing. Lots of smoke, but no more power.

 

[MASTER Brian]

Re: Evinrude XP150 not accelerating

Here are my other findings...<br /><br />Once again, it does idle fine and I can even rev the motor up with the fast idle lever. However, when in gear and I give it full throttle the RPM's don't go up and the boat won't accelerate.<br /><br />Another thing I noticed today, while reving the motor in neutral I hear a clinking noise and can feel a slight vibration in the gear lever. It doesn't do that while in gear. I'm not certain, but I don't think the noise is coming from the engine itself. I don't remember this prior. <br /><br />I may have imagined this, but after reving the motor in neutral then putting it in gear and trying to go, it seemed to have more power for a short period.<br /><br />The primer bulb stayed hard, telling me it had good pressure and pumping it didn't make any difference. What should the fuel coming out of the pump look like, should it be a steady flow or should it pulse with the engine? Mine seems to be pulsing with the engine, but it is a good stronge flow.

 

[sikpnter]

Re: Evinrude XP150 not accelerating

Rule of thumb for trouble shooting outboards is #1 compression #2 spark #3 fuel, this order is crucial. If that cyl is still that low after decarb you need to pull the head and take a look.. 55psi is unacceptable. They need to be within 10 to 15 percent of each other. If you have a bad cylinder it can cause every problem you've had so far and then some.

 

[MASTER Brian]

Re: Evinrude XP150 not accelerating

Fair enough, do these have re-usable gaskets or do I need to get another one? <br /><br />Like I said I'm used to jetski 2 strokes and I realize some things are different between outboards and jetski's. Is there anything special to keep in mind when pulling a head on an outboard?

 

[sikpnter]

Re: Evinrude XP150 not accelerating

Like wildeone said "get a manual" manual will have headbolt torque values and all you need to know, ebay is full of them. Get new gasket for sure and please let us know how you do.

 

[MASTER Brian]

Re: Evinrude XP150 not accelerating

I'll get on ebay and see if I can locate a manual or go elsewhere and get one. In the meantime, I'd like to get this head pulled and see what is under there. If there isn't anything special to do when pulling it, I'll yank it off and take a look.

 

[sikpnter]

Re: Evinrude XP150 not accelerating

Nothing special to pull just need torque values and bolt pattern to reinstall also check the gasket good for signs of leakage, that can lower compression also.

 

[MASTER Brian]

Re: Evinrude XP150 not accelerating

I have a few other questions, while I am waiting to get the head off and get a repair manual to me.<br /><br />What this reminds me of is when my jetski engines would occasionally ingest a bit of water. They would run bogged down for a bit, until the water cleared out then run fine, but like I said I've replaced the water/fuel seperator and one tank has almost all new fuel in it. Of course the fact it revs with the fast idle and the fact of the low compression on the one cylinder makes me want to rule that out.<br /><br />Where should the tach draw it's reading from? The reason I ask is that my tach doesn't always kick in until RPM's come up a bit and even then sometimes it seems somewhat intermittent. I am wondering if this also doesn't draw off the bottom cylinder on the port side. Makes sense that if that cylinder isn't operating properly then it wouldn't register RPM's correctly. Am I correct?<br /><br />On the "mid section" of the outboard assembly there are two covers just about where the mid section meets the lower unit, what do those cover? Can anything be inspected by pulling those off? I have an "owners manual" that gives a part breakdown, but it's not clear in the pics. They are just listed as "cover, mount bracket lower".<br /><br />I also notice that there is a cylinder head cover mounted to the cylinder head. Can anything be seen by pulling just that or does that just reveal cooling passages? (that's assuming it comes off with seperate bolts than the actual head itself, otherwise I realize it doesn't matter and the head will just come off with it.)<br /><br />Also, I have a tank I can fill with water and set my motor into, will that provide enough drag on the prop when in gear to somewhat simulate being at the lake or not? I've seen somewhere where it said not to run more than so many RPM's while connected to a hose, is it safe while setting in a tank of water? I'd like to be able to somewhat test any findings without having to drag it all the way to a lake.<br /><br />Last question for now... I did the decarb as per the FAQ's on this forum, which calls for running 15 minutes and set 15 minutes and repeat up to about 3 times. Being as I was only able to run a decarb for about 5 or 6 minutes the 2nd time through and it was still smoking profusely when I ran out of the decarb fuel mixture, should I run another batch through and see if that helps some more? ...I'm curious if that would possibly de-stick the ring if that's my problem or if I am better off at this point in waiting until I've had a chance to pull that head and take a look.<br /><br />Thanks for all the help...