85 Evinrude XP 150 falls off at full throttle

"I have an 85 XP150 that was o

"I have an 85 XP150 that was overhauled about 25 hours/2 years ago. It ran perfect last October. When I put it up for the winter I added fuel stabilizer and ran it on a hose to get it through the system. My son has used the boat twice this year had no complaints first time out. second time out he complained that it would cut out at full throttle. I finally got around to taking it out and it runs perfect up to about 35-40 MPH or 3200 RPM and about half throttle then if you hammer on it it will begin to run up normally until about 4200-4500 RPM and about 45-50 MPH then it cuts out like its running out of gas. (Normal WOT for this boat/motor gets about 57 MPH @ 5000-5200RPM depending on trim.) if you back off the throttle to about half it picks itself up and runs smooth again. I've been told by a mechanic that its probably the high speed stator gone bad, but I had a new stator put on it about 5 years ago and the hours are rediculously low. I suspect the VRO pump Diaphram as it has given trouble every 3 or 4 years since I've owned it. Usually after the engine kicks back when trying to start. I thought a diaphram kit was available for low dollars but the same mechanic who suspects the stator said that there was not a kit available he'd have to sell me a new VRO pump for $379.00! What do you guys think?"

"There are kits available if h

"There are kits available if he looks in the 'old' system mached cathalogs the different parts for the VRO is listed, except oil unit. Part numbers are still alive! If there is trouble with the air pump membrane when the engine misfires (crank case combustion) he should have changed/installed the puls limmiter valve the first time it broke!
Perhaps a rebuild kit for Your mechanic?"

"actually he's not my mech

"actually he's not my mechanic. he works at the dealership where I bought the motor about 15 years ago! The Guy who I was using (the one who overhauled it) has either moved or gone on an extended vacation. The reason it needed to be overhauled was because the oil line cracked on a trip to the lake and allowed the VRO to suck air instead of oil and it locked up on me. I asked him if it could be prevented in the future and he told me to mix 4oz of oil with every 6gal of fuel I put in the tank and that if anything went wrong with the VRO in the future it would overheat but still have enough oil to prevent destroying the motor. he said i'd have to change the plugs more often but that it would be cheap insurance. I think he had checked the pulse limiter the last time the VRO pump failed and said it was OK. all other times it has failed it wouldn't run at all, which has me baffled. does it sound right that it may be pumping enough fuel for half throttle and not enough for Wide Open. and should I change the pulse limiter anyway since this is the third time the air pump has failed if indeed that is the problem??"

"It may be the air motor membr

"It may be the air motor membrane, or the fuel membrane (both may be bought as seperate spares. The best way to test is to put a fuel pressure tester between the pump and the carbs and check the pressure. However first check the anti siphon valve at the tank top, filters etc. Does it help pumping the bulb? As for oil lines note there is a 'new' type of line that does not crack and get hard as the old one did."

hi can anyone tell me the corr

hi can anyone tell me the correct mixture of petrol and 2 stroke for my evinrude it is a 1979 49b36 4hp
thanks
kait

"Checked fuel pressure 4 psi a

"Checked fuel pressure 4 psi at idle. At 3000 rpm 2 psi. Due to running on hose, unable to run wide open. Does this sound right? or is it low?"

"So far so good, but the quest

"So far so good, but the question is what happends when You pass Your 'trouble' rpm 4000+?"

AhHa!! I took her to the water

AhHa!! I took her to the water this past weekend and as usual she fell on her face. This time however I had someone in the back seat with the hatch open and primer bulb in hand. As soon as she fell off I had them squeeze the bulb and guess what? She picked herself up and ran like a champ. I guess that confirms my theory that my problem is the VRO pump. Now the question is should I purchase a new VRO pump and pulse limiter at $379.00 or a conversion fuel pump for about $150.00 and pre-mix. I've never been a huge fan of the VRO system as it came out on my engine due to the fact that you could loose oil flow without any warning (see previous post). I understand that later models corrected this with an oil flow sensor. but one thing is certain if you pre-mix and your getting enough fuel to run your engine you know your getting oil. any ideas pro or con to converting to pre-mix on this engine?

Take apart the pump and check.

Take apart the pump and check. You may probably just have to get a rebuild kit for either the fuel section or air motor.

"I can't find anyone in my

"I can't find anyone in my area who will even talk to me about rebuilding my pump they all want to sell me a new one, all but one say rebuild parts are not available, only one independent mechanic offered to order me the fuel pump to convert to pre-mix. how can I get the part #s for the rebuild parts? I've looked all over the net and can't find them listed in any parts breakdown. haven't even found anyone who shows the conversion pump as an option but the mechanic who offered to order me one swears that its available through Evinrude. Even when I asked him about the rebuild parts he didn't want to talk about rebuilding it. He said that every one he'd ever tried to rebuild didn't last very long. could it be that they are afraid that if they rebuild it and something happens to it (failure) they could be held responsible for engine damage, But if they sell me a factory pre assembled one that responsibility falls on the factory??"

"All parts except the oil unit

"All parts except the oil unit are available as spare parts and any authorized dealer should be able to get them!
If a rebuilt pump fails, the reson is normally that the problem causing the failure has not been corrected, like canck case combustion. If air motor is gone, change the membrane and the pulse limiter. If fuel membranes are leaking due to age, change the membrane. If oil alarm or pump piston is damaged -change the pump! If fuel is leaking into air motor, change the housing with the seal. Sorry, but I do not have the numbers, probably Joe have som old System Matched
catalogs they are listed there."

"Morten, I really appreciate y

"Morten, I really appreciate your taking the time to reply to my posts, but you have completly ignored the question about converting to pre-mix. and I'd really appreciate your opinion on that. To me it seems to be a win-win situation especially since my engine does not have any form of warning regarding oil flow."

"If You want to run pre mix, o

"If You want to run pre mix, ok. If You have a fix tank of some 25Gal+ and leaves the tank full and engine/boat unused for a month or more, do not forget to shake the rig well before starting again! If running 6 Gal tanks, no problem, but I am not in favour of premix in bigger tanks and prelonged storage."

"Update, I went down to my loc

"Update, I went down to my local dealer(the one I bought the motor from 15 yrs ago)to try once again to get them to look up the diaphram kits and after speaking with a different mechanic was told that they did not keep any of the old system mached catalogs that everything was supposed to be on the computer system and that Bombardier had quit offering the diaphram kits since they took over OMC. He did however grab a newer looking catalog off the shelf behind the counter and turn in it to the page that showed the VRO pump and hiding there at the bottom of the page was the air motor kit and fuel section kit. then if that weren't enough he went into the back room and produced the air motor kit from stock. All this looking to find the part nos, and me arguing that they did exist, took about 30 minutes and once they found the nos. they had the parts in stock!! I couldn't believe it! Then he made the comment that it was a good thing the owner wasn't there because he would throw a fit if he knew they had spent half an hour looking for part no's that cost less that $35 total. and that they had basicly been trained to sell the more expensive (10X) VRO pump because their time was too expensive to be chasing parts that are so cheap. What A Rip Off!! I certainly hope that there are some dealers out there who are more concerned about taking care of their customers instead of padding their pockets! thanks for all the help!! I'll let you know how she runs when I get the kit installed."

"Also was told by the same mec

"Also was told by the same mechanic that if I wanted to pre-mix that there was no need to get any conversion pump just disconnect and plug the oil line of the VRO. as for the mixing problem my tank is 18gal and I have to trailer the boat about 30 miles to the nearest lake surely that would be sufficient for mixing purposes especially if I estimate and add the oil to the tank prior to adding fuel. I just don't trust the VRO system. I've seen what happens when something goes wrong! So I think I will probably go the pre-mix route, Better safe than Sorry!"

"Just keep in mind that if the

"Just keep in mind that if the pump or fuel system goes bad and engine suffer from lack of fuel, it will even suffer from lack of oil! Normally the 'worst' that happends with the VRO systems is too much oil If the pump starts working too much caused by fuel membrane/valves leaks, air leaks in system or similar. I have never in 15+ years as OMC dealer seen a pump not giving oil unless the oil hoose has been defective or filter in oil tank clogged by gel. However I have rebuilt numerous engines from lean burn, lack of fuel. But a 30 mile ride will probably keep you fuel mixed."

"I know that this is going to

"I know that this is going to sound stupid, but bear with me. I am working under the assumption that an engine running on pre-mix that gets enough fuel to run properly is getting adequate oil 50:1 is 50:1 right. So I'm confused because I'm under the impression that 50:1 mix ensures lubrication to the point that it is so lean the engine won't run. right or wrong? I can understand that lets say a carb gets stopped up but the operator continues to run the motor (even though it's missing horribly) then the cylinders that the stopped up carb feed will suffer. no fuel equals no lubrication! but if the engine runs smoothly I don't see how it could trash the engine. But I'm no expert either!"

"In general You are right.Prov

"In general You are right.Providing the engine (all cylinders) gets the right mix of fuel(and oil)/air, aprox 15:1 (wheight equivalents) no harm will happend, assuming temp/cooling works. If You browse this board and take a look on the 'major breakdowns' the majority is caused by the fuel/air ratio has been disturbed. I am rather sure that most of theese cases could have been avoided had the operators known a litle more about the physics of the engines. In most cases it has started with rough idling, lack of 'hole shot', drop of top end, engines bogging. Still quite a lot keeps on pushing and 'testing' until 'dooms day'. The VRO and premix does in fact the same, the VRO just do the pre mix in the fuel pump, while the owner does it in the tank.
In cases involving clogged carbs, filters etc the result will be the same. In one case the VRO has an advantage and that is an air leak in the fuel system or bad pressure caused by defective fuel pump: The VRO will encrease the oil mix and lubrication giving a rather visible warning that something is going on, and may prevent a sizure of cylinders and 'bluing' of bearings/cranckshaft/conrods etc.
Another aspect is the 'gel' problem'. Modern TCW oil (TCW-3) has a grater resitance and tolerance level of humidity (NOT WATER!) than the old TCW-2. This oil is designed for use in seperate oil tanks. To service and check is rather easy, out with the pick up and check the filter. The tank is small and easy to clean and ormally mounted in a protected place. The main fuel tank is something else. Inspection possibilities normally limmited to the fuel gauge sender, but the biggest threat is the ventilation hose! As fuel in the tank is consumed it is replaced with air sucked in from outside the boat. At the best with just below 100%humidity. The fuel pick up tube does not go to the bottom of the tank, but leaves some Gals of fuel/water left when the engine stops. One thing is to install a waterseparator to prevent the water entering the engine, what is worse is the effect the water in the tank has on the 2 stroke oil!
To make it short: As long as all systems works, evrything works and boating may be a happy experience limmited to running costs, fuel mix or VRO!
To keep the systems working is the question. How to minimize risks and reduce maintaince is the big question. I used to run a Boston Whaler 17 Outrage with engines from 115 -225 Venom. Operating some 100hrs every seson. Every spring, fuel tank had to be 'drained' for about 1 gal of water, and that was NOT from a leaking fill cap!
I had customers that killed the engine not the first but second season after disconnecting the VRO, and normally early in the season! In all cases water/gel found in the fuel tank, filter, pump, carbs!
Personally I preferr the VRO system, not that it is perfect, but with minimal service it is the safest."

"You make a valid point about

"You make a valid point about the symptoms you mentioned and the pushing and testing until doomsday. I sometimes wonder if I'm not guilty of that myself. although I added oil to the tank for my test run the other day, I didn't add it to 50:1 (because I wasn't sure the VRO was the problem). It did occur to me that by pumping the primer bulb and running the engine rpms up that it was possible i'd not be getting enough oil for the period of time I was useing the bulb to feed fuel to the engine (especially if the VRO pump was bad). I therefore knew not to keep this up for any longer than absolutely neccessary to confirm that the VRO pump was indeed the problem! so point well taken there! I've never had any problem with water I keep my boat in a garage which is climate controlled. so maybe that explains why I haven't. Thanks for the insight though. I may revisit the VRO issue. I'd just feel better if every time it hickups I didn't ask myself, Is it getting enough oil or is it about to come screeching to a halt? and pre-mix seemed to be a way to put that issue to rest however it appears that it may open another can of worms. Hmmm food for thought! I will re-post once I get the VRO kit installed and let you know how it does and what I decided to do with it Thank You again for the advice!"

"removed and disassembled VRO

"removed and disassembled VRO pump found no holes in diaphrams either air motor or fuel pump. It seems the last time it was rebuilt someone glued the fuel housing with some pvc glue or something it didn't stick though as soon as I loosened the screws it just kind of flaked off. there was an O-ring on the fuel pump side that didn't show up in any of the drawings that came with the kit, I don't think it belongs there as it appears that the edge of the diaphram forms the housing gasket? I did find that the fuel valve disc seemed to be in backward as it has a slight curvature to it and wouldn't seat naturally against the plastic diaphram body so I turned it around got rid of the questionable O-ring and reassembled the pump. It seems to not have any vacuum leaks as plugging any of the ports will hold it in position. should I try it on the motor or do you think I should take it to a mechanic to be tested further?"

Try it on the engine and see w

Try it on the engine and see what happends. No sealing material anywhere when assembling!