Yamaha VMAX starting issues

I’ve got a 2000 Yamaha VMAX OX66 150hp motor. The thing I like about it is when you hit the key, it’s on. End of story. The last couple of weeks it’s been starting real hard. I have to crank it 5 or 6 times before it starts, and then when it does start, it chugs and smokes like never before. I just installed a new fuel line and fuel bulb, and it’s still acting this way. It was doing this before I installed new spark plugs last week, and that did not fix the problem either.
So…any suggestions? I don’t know much about the fuel pump, but could it be going bad? Once the motor starts running, it’ll run across the lake with no problems. Seems to be a starting issue only. I would assume that if the fuel pump was going bad, it would not run so well.
Looking forward to your help as always, guys.

I’d start with the fuel filter it’s a lot cheaper and could be an easy fix If the problem continues then I would check the fuel pressure to see if it is a pump

Sounds like BAD GAS…

Dog

Bad gas….funny you mention that because I was considering that too. I do have a new fuel filter too, so I think I’ll put that on and see what happens. Just hadn’t gotten to it yet. Won’t hurt.

Some Seafoam has helped out others as well if fuel-water related.

I have the same motor and just started having the same problem! Ive tried all thing suggested above! haven’t fixed the problem yet!

like ya said! hit key starts and dies 3 or 4 times and it will go! I think its getting to much gas or too much oil! cuz if you put fast idle up it will start first time!

first time you start it for the day it takes right off no problem! after its warmed up and shut it down and sits a bit it starts hard! like gas is loading up in the cylinder while it is sitting! im betting the high pressure pump is not relieving pressure after shut down! and passing gas into the cylinders! thats my thing to check! going to have to take it in to check that!

Bet that you will bee needing to replace the fuel pump diaphram’s. That’s what fixed my hard to start hot V-max…

Ah, thanks Greg. I’m leaning towards it being something of that nature. How big a job is that? I need to go open up my cowling and take a look around at things.

Lots of good info on Bass boat central about swapping/replacing pumps sounds plenty easy enough and fairly cheap too.

Quote:

---

sounds plenty easy enough and fairly cheap too.

---

Now THAT’S what I like to hear!! So I would just change the whole pump out instead of mess with gaskets/diaphrams?

That what people tend o do, since you don’t save a lot and it’s kind of delicate to change them from what I understand, IIRC pumps were around $40 a piece last I seen and you would need 3 of them, again BBC has a lot of info in their Yamaha forum. May even be a sticky, I don’t venture there anymore

B, a good friend has a comparable motor and he had the same issues you’re having. It turns out that the “housing” of fuel pump had a hairline crack in it and was causing the pump to suck air (hard starting and lots of turning over buts once running at higher RPM, ran fine). It’s not something you can really see but that is the very first thing that I’d replace based on my what I’ve heard of that motor.

Adam

Adam,
Thanks for the info. I’m going to take a look at it next chance I get.
And Nick, I would really need three of them? Why 3 and not 1?

Now that I think about it, here’s another piece of the puzzle- I think it is an air leak of some sort, whether it be a hairline crack, bad diaphram, whatever. But it seems I have to pump up the gas bulb, and it STILL starts hard. I’m trying to find my cd-rom that has my motor manual on it so I can look at it, but that’s been a wash thus far. Thanks guys–

My take the pumps are pretty much a wear and tear item, and it’ll take you sometime to do the work, though it sounds easy enough, thus far guys just replace them all when the do it. IIRC there is a proceedure to test them too, something like loosen them off the block, pump primer bulb and you can actually see gas leaking, BBC is a wealth of info on this. I forgot they have posted a way to test time before replacement, I mean I suppose you could do just 1 or 2, that would be up to you.

Although it sounds a lot like the Low pressure pumps, small chance you O2 sensor is part of the issue, or you could have some crap floating around in the VST tank and would need to clean that.

Thus far the only issue I’ve ever had is water pressure poppit valve that stuck open and gave me low water pressure, and between synthetic/semi synthetic oil and ringfree and seafoam in every single tank, never had an O2 issue. I do expect to replace my LP pumps in the future, because they seem to wear out. I only have 70 hours on my motor too.

I would say 90% of what I know about my Yamaha ox66 came from reading BBC.

What’s a VST tank?

Got a little mixed up in my reply, most likely not the VST tank filter for hard start, those problems tend to show up as not running good when you’re up and moving.

The VST tank IIRC, is up higher on the “driver’s” side aluminum tank attached to the motor fuel lines in and out, some electrical, I’ve been on my phone all day so I can’t link you a pic.

No prob, Nick, whenever, if you could. I’ve really gotta find the cd-rom that has my manual on it, then I’d really be ahead of the game. But it’s still MIA right now…

pumps: http://www.bbcboards.net/zerothread?id=413430

VST (though it’s probably not your problem) http://www.bbcboards.net/zerothread?id=449413

I think there’s enough info there to not need a manual, though if one had a way to recieve one very big file….. and I’d have to dig for it too.

Thanks Nick! I appreciate it. Now I just need the time to go actually check it out and comprehend it!

Something I think I may have forgotten to add in my previous posts- when the motor does finally start, it chugs and chugs, and smokes like you’ve never seen. Then when you hit the throttle and buzz across the lake, no problems at all. Pretty weird.
Something else I was thinking; if I get this thing fixed, I wonder if it’ll improve any fuel mileage? I’m doubting it will, and if it does it most likely won’t be any I would notice, but didn’t know if anyone knew about that. I suppose these are parts that I need to get replaced anyways, so let the fun begin.

Fuel mileage? whats that…. I don’t understand….. LOL my boat in near perfect conditions gets something like 3.2 mpg, otherwise. right around 2 anywhere else, but It’s reasonably fast and super reliable. It’s the trade off you get with the OX66 versus the HPDI, Save some $ and a little more performance, can still buy a heck of a lot of gas before the HPDI wouldve been a cheaper choice.

Let me know if you need anything else.

Well Nick, I’m pretty thrilled this morning…I found my cd-rom that has all my Yamaha manuals on it. So if anyone needs anything for 1984-2003 models, 2-250hp, I’ve got em!

Going to do some reading up on it tonight, looks like a lot of good stuff in there for the fuel system, which I do believe is where the problem lies. Going to take apart the fuel pumps, if I can figure that out, and do the pump test on them and go from there. I sure hope it’s something easy….

what you were waiting all this time to find you manual? I told ya I probably have one.

Again the links should give you everything you need too, sounds like it’s more work than, skill.

Good luck buddy!

Thanks! I’ll take all the good luck I can get!

So, I took the cowling off last night and looked around, and don’t really know what I’m looking at. The first pic is a large cannister that I’m guessing is not (hopefully) my concern, judging by the prices on this link.
http://www.boats.net/parts/search/Yamaha/Outboard/2000/VX150TLRY/FUEL%20INJECTION%20PUMP/parts.html

So I’m guessing that the fuel pump assemblies, shown in the 2nd pic, are what I need to be looking at to see if they leak, right? However, I thought there was 3 of them, and I can only find 2 after a short time looking. Also in the diagram on this link, I only see two.
http://www.boats.net/parts/search/Yamaha/Outboard/2000/VX150TLRY/FUEL%201/parts.html

Am I on the right track here?

HaHa….maybe I should read, eh?

I see on the parts list that they say how many are required, and they say 2, so that answers that. I guess the small things are the low pressure pumps, and the big cannister is the high pressure pump. I do believe I’m looking in the right area because last Friday I was out and it started right away, then struggled the rest of the day. Made no sense to me.

Because of that, though, I don’t feel it’s a filter issue. If it were, I think I would be struggling all the time with starting and running. When it does get started and going, it runs great. So…that’s where we are now. I plan on working on it today (fri) afternoon and see what happens with it. Apparently, I guess I’m supposed to have them off the body of the motor and then pump up the bulb and see if they leak. I sure hope it’s that easy and they leak like crazy, so at least I’ll know where the problem is. Motor is running just too damn good for this to be too big of a deal.

I also took apart the water seperator assembly, and there was crud in there, and I got most of it out, but today I’ll take it apart again and really make sure it’s good and cleaned out.

I guess what’s being called the VST filter is in the bottom of the big cannister, and I’m pretty hesitant to take that all out. I guess I can worry about that if these fuel pumps don’t do the trick. But for now, judging by what I see in the diagrams, I think I’ll let it be.

I like reading that the one guy said after doing this, it was like he had a new motor. I think my motor has been well taken care of, but I’m thinking this could be a part that’s just needed now and will hopefully be the difference.

Here goes nothin…..

Awesome, yup looks like you’re on the right track Yeah, either I or the link probably put the three pumps in your head, I forget though vastly similar, I still got a 200.

Certainly a good idea to clean up the VST tank, might as well do it all if you’re doing the work. I added a external fuel filter water seperator in hopes I never have to mess with the VST.

Looking forward to your results later Hopefully I’m on the right track, otherwise atleast you know how to do it when the day does come

Any updates?

Hey Nick,
Nope, not yet. I messed with it Friday and was going to take the fuel pumps off and test em out, but I tried to take one off, and it wouldn’t budge. I figured if I do take it off, the gasket will be roasted and then I’ll be out of a motor, period. Until I get it fixed. So, I figured I’d just leave em on so I can go out this week, and I’ll have the parts ordered tomorrow, so then I’ll get it done over the weekend I’m hoping.
I just hope it works. I hate to just be a part changer, but I’ll be in only about $95 or so, so I guess we’ll try it.

I’ll keep ya updated–

Quote:

---

was going to take the fuel pumps off and test em out, but I tried to take one off, and it wouldn’t budge.

---

Ok….first off, it turns out…I’m an idiot. I took the wrong screws out the other day, so of course the pump wouldn’t budge.
My buddy Jay and I took them off tonight and they came right off, and better yet, the gaskets came off pretty clean too. Scraped just a bit off with my thumbnail, and I was good to go. Did the pump test, and sure enough, the top pump was leaking, Jay said. So we installed the new ones, put the Yammy on the earmuffs, and it sounded pretty good, I gotta say.
When I had the old ones on, and I pumped the fuel bulb, you could hear a lot of noise. When the new ones were on, I could not hear that noise at all. I take that as a good sign.

The real test will come next week when we take it out and see how it does. I gotta think the problem has been resolved, but we’ll find out for sure soon.

Sweet!

Well Nick, after backing the boat in the garage and being on the water most of the day today, I’ve only got one thing to say to you it seems….

You da MAN!

Problem GONE, I’m very happy. It’s so nice to have the turn-key starting back and going. And it’s an even better feeling that I did it myself, along with the help of my buddy and fellow IDOer Jay W, and saved a little $$.

Could not have done it without you and your time, it’s greatly appreciated! And thanks for helpin out, Jay!