Fuel problem, please help.

[Blue_Runner]

2004 Yamaha 150 carbed 2 stroke.

Above 4500 RPMs the fuel flow cannnot keep up and primer bulb starts to go soft allowing the motor to cut out. Runs smooth as silk anywhere below that. At 4500 and above someone can squeeze the ball and the motor will not cut out.

Couple things - installed a new primer bulb to be sure it wasn't that. Tank pickup seems to be free flowing and clear of obstruction. Racor F/W separator a little over 1 yr old. In-line filter seems fine, clear from obstruction and trash.

So, what could it be other than the fuel pump? I'm going to go ahead and replace the 2 filters anyway, but don't think it is going to help.

[Cam]

Sounds like a hose is collapsing on you. Have you checked the tank vent for a partial obstuction. Try running motor on a seperate line/tank and see if that solves the problem. Happened to a friend of mine and it turned out the inside of the fuel hose was collapsing under high RPM's. Check the obvious/cheapest things first.

[Blue_Runner]

Oh yeah, forgot to mention, checked the tank vent - no obstruction whatsoever.

I agree, I should run it on a separate tank and see what happens. If it were a line collapsing it seems I would have trouble priming the ball while my buddy is running it above 4500? I'm able to keep up and it doesn't "feel" like a fuel line problem.

[Cam]

I saw the fuel line that collapsed on my friend after he replaced it. It seemd like the fuel line had a bladder in it (a hose within a hose). some parts were still intact while a small portion of it was not. That was the part that gave him the problem. Running on a seperate line/tank is the way to go now to eliminate engine itself as being the problem. Good luck!!!!!!

[Blue_Runner]

Thanks Cam! I agree with you. I'll do that this evening.

For now, let's pretend I do that and still have the problem - what comes next?

[Destroyer]

Buy a Honda?:you:


(Sorry, couldn't resist)...I'll keep quiet now..:zip:

[Blue_Runner]

:nut:
Ouch!

[Blue_Runner]

Where are all of the internet mechanics? Taking the day off? Hello? If I don't hear back soon I'm going to go by the Honda dealership to look see about a new motor. :beer:

[nymack66]

Sorry my friend, I do not know anything about a Yamaha..

[Blue_Runner]

Nymack, its the same as a johnnyrude...just has a different word on the cowl! LOL

[nymack66]

Ok I will give it a shot,
Run it with an external portable tank to eliminate the possibility a vapour lock (clog air vent or bad fuel cap) or anti syphoning valve issue on the tank.
If problem persist you will need to do a fuel pump test, I am not sure what the procedure will be on a YamahaEvinrudeJohnson :)

[whatknot]

I'm going with the fuel pump doing a slow death on you. I think your supposed to have 45 lbs pressure on the bar. Mine crapped out recently and I was pushing 5 lbs. That's only a guess....Good luck with your real mechanic!

[willy]

Blue from my previous experience with a similar problem, make sure your primer bulb is good, I went thru three before I found a good one believe it or not. Second time with same problem, in engine filter was clogged and the fuel pumps had taken a dump.
That was inspite of a Racor 10 micron set up.
The Mercury did the same thing on me but it was a fuel line that had a small split in it and would take on air, same thing when I pumped the ball it did OK cause I was forcing fuel into the engine but let on its own the darn thing would suck air.

[HookedOnMarsh]

I'll bite I guess. You mentioned that the primer bulb was going flat. If you're not mashing it and it's going flat on it's own then you just ruled out your engine and fuel system from the bulb to the engine. Period. Has to be.
The problem lies between the other side of the bulb and the fuel in the tank. Maybe something is clogging up the inlet strainer in the tank? Bad primer bulb check valve(happens to me every 2 years). Trash caught in the shutoff valve at the tank, collapsing hose between the bulb and the tank. Or most unlikely, but not forgotten is a clog in the air vent.
Hope this helps.

[THEFERMANATOR]

Is the racor before or after the racor? If it is before I would replace it. I change my spin ons pretty regularly espescially with this ethanol crap we get now. Also what fuel line are you running? Make sure it is a new style marine grade line as most automotive lines are not meant to run under a vacuum like an outboard does. Verify the tank vent is good. I pulled the one out of my pro line even though it looked new and it had a big chunk of corrosion inside it. It still flowed air, but not enough when I dropped the hammer. Also if your tank has a anti-drainback valve in it, pull it out and clean it. Over the years that check ball gets varnished pretty badly and will cause it to obstruct the fuel pick-up. Most people just remove the check ball from them to prevent from having this problem. Start with basics and go from there. Also I like to use marine grade EFI fuel line as it is HEAVY walled and will not collapse even when you are hammering down on it.

[JohnnyO1]

Blue Runner

I kind of had the some problem last year. Know matter what I replaced my primer ball kept on collapsing. It usually would happen anytime after 3000 rpm. I pretty much replaced everything before the motor and now motor runs perfect.

A couple of things that I learned during the process:

1. Just because you have a brand new primer ball it doesn't mean it is working properly. I replaced my primer ball with one made by tempo later to find out they had a problem with them. Went with one made by Quicksilver for Mercury and no problems since.

2. There is something called a anti-siphon valve in your fuel line. Basicly it is a fitting with a spring loaded ball that prevents fuel to return to the tank. If the ball is frozen it could cause a restriction. Usually located after or at the fuel pick up by the tank.

3. The new ethanol fuel has a tendancy to degrade older fuel lines. That being said a piece of the fuel line could have broken loose and caused a restriction. If you replace your fuel lines just remember there are two types. One that can be exposed to uv light and one that cannot.

4. The fuel pick up has a screen in the tube. With the new ethanol fuel removing any dirt in your tank it is possible that dirt could be clogging the screen in the pick up tube. I spoke with a Mercury Rep. at a boat show and he told me to remove the screen as long as I have a fuel filter. Upon removing the screen I noticed some dirt built up on the screen which could have restricted the fuel.

5. I also changed my fuel filter to a racor fuel filter/water seperator. I did this because everything else was replaced. Filter has a clear plastic bowl which is easy to see water building up. I drain it about once a week.

That being said I have a Mercury motor not a Yamaha but I would think that the fuel delivery would be similar.

Hope this helps.

Good Luck!

[Cam]

ALL excellent advice!!!

[Blue_Runner]

Thanks fellas!

I hauled it down to High Rock yesterday evening to run it on a separate tank. It behaved the same except the primer ball stayed firmer but still felt as if it had air in it. Best I could tell anyway - it was just me so I had to pull it down to check the ball.

A couple things -

* tank vent is clear. I can blow into the tank.
* fuel tank pickup seems clear - I'm able to blow bubbles in the tank.
* I'm running a racor /w the clear bowl. The racor is before the primer.
* when running on spare tank I bypassed the racor.
* I would love to replace fuel lines, clean the pickup screen, etc. but will have to remove the tank hatch to access it. It has never been removed.

I think I have ruled out - primer bulb, fuel lines (unless it is the short piece from primer to motor which is only 5 yrs old), fuel vent, fuel tank pickup, racor fuel water separator.

Things I have not ruled out - fuel pump, inline filter (should have removed the screen as a test at the lake but forgot), & carbs.

Question for my internet mechanics - could trash in carbs or torn carb gasket cause these types of symptoms? I wonder if it is sucking air through the carbs?

Thanks very much guys!

[jjjtronics]

Try this; using a piece of clear fuel line, adapted inline with the fuel line, look for air bubbles running along with the fuel flowing while the engine is at the failing rpm. If you see air bubbles, you have got a vacuum leak somewhere, and that will make your life misserable.
I had a VERY similar problem once, using this clear line method, found a microscopic pin hole in the aluminum fuel pick up tube in the tank.
Remember that thanks to whoever made it a design-rule-law, outboards run on a vacuum- type fuel system all the way up to the pump, which is mounted next to the carbs/injectors, that way there is never-ever pressure on the fuel lines from the tank, which avoids leaks and fire hazards to almost zero. But vacuum leaks are hard to trouble-shoot, but, if the pums are pumping well ( checks with fuel pressure gauge ), and the fuel supply is good ( enough and free of bubbles ) your motor should run good, unless there is a problem with the motor itself.
If you have good fuel supply, I have cleaned my Yamaha`s carbs a couple of times and could help you out on that.

[Blue_Runner]

Thank you JJJ, good ideas.

I've cleaned my carbs with some help from a buddy twice. Might be time to try that agian. I will go ahead and get a carb kit to replace the gaskets. Last time in they were a tad brittle which makes me suspicious.

[nymack66]

BTW where are the pictures ? :)

[Blue_Runner]

My goodness, I'm in crisis mode...my boat is in ICU and all you can think of is pictures! Shame on you! :hide:

[Blue_Runner]

Update: I took the boat to a guy down the road who has quite a bit of experience working on outboards. He diagnosed it as have a bad fuel pump (1 of 2). Well this is great news because it is exactly what I suspected.

He is replacing both fuel pumps and I am supposed to be able to pick it up this evening. If I get it in time I'll be off to the lake for a test run. Wish me luck!! I'm ready to get back out there. I haven't put nearly enough hours on it this year.

[bradford]

Thanks fellas!

* tank vent is clear. I can blow into the tank.



I wanna see pics. :nut:

[Blue_Runner]

LMAO!!

Pictures ARE cool aren't they? No pics. He rebuilt the two pumps and showed me the one diaphragm that had a HOLE in it. He said it looked like our good buddy ethonal caused it.

Yesterday evening as I was about to put some burgers on the grill I got a phone call to meet him at the ramp for a test drive.

**WARNING - WHAT YOU ARE ABOUT TO READ IS SHOCKING**
I reluctantly turned the burger grilling operation over to my wife.
** TOLD YOU IT WOULD BE SHOCKING**
:oh::oh::oh::oh::oh::oh::oh::oh::oh:

From there I headed to the ramp and we dropped it in the water for a test spin. I drove it like I stole it and no hesitation, no starving for fuel, none of that. She purred above 4500. Problem solved!!!

While in the shop I had him replace the impeller, which I had already purchases for $25 (was going to do it myself) and supplied to him. He did that and replaced the o rings around the housing as well. Total out of pocket is $200 for the whole job - 2 rebuilt fuel pumps and replaced the impeller and o-rings. I was like, "is that it, $200?" I think I found my new favorite local outboard mechanic!!

p.s. wifie did a spectacular job on the burgers and I scarfed down 2 of em when I got back. Props to Mrs. Blue! :clap:

[RWilson2526]

Anytime you can have anyone fix anything for $200 is a BARGAIN!.....Good job.

[Blue_Runner]

Thanks RW - I fully expected him to say $500.

One thing is I had pretty much already isolated the issue by running on a spare tank....the fact that I could squeeze the ball and keep it going above 4500 helped too. I wrote down all of the things I did on a note and gave it to him when I dropped it off. Not to say he wouldn't have known to look at the fuel pumps first anyway but I like to think I saved him a little bit of time. Who knows?

My dad had him do some work on his 40hp evinrude recently. Rebuilt the carbs and changed the impeller in it for $265!

[THEFERMANATOR]

Geez, I REALLY need to raise my prices. I did an annual on a YAMAHA 225HP 4 strokme a month ago for a guy for $375 which included the oil(CASTROL SYNTEC), filter, water pump kit, MERCURY racing synthetic gear lube, cleaned and inspected prop seal and shaft, decarbed it, and did all the other goodies to it as well as ran a new harness for his electric jackplate.

[macojoe]

THEFERMANATOR Geez, I REALLY need to raise my prices. I did an annual on a YAMAHA 225HP 4 strokme a month ago for a guy for $375 which included the oil(CASTROL SYNTEC), filter, water pump kit, MERCURY racing synthetic gear lube, cleaned and inspected prop seal and shaft, decarbed it, and did all the other goodies to it as well as ran a new harness for his electric jackplate.

I payed $1200 for complete tune and work up, VST, Filters, new water pump, gear oil, oil change and filter, computer read, ect... ect...:cen:

[phester]

Blue, I had a similar ethanol problem two seasons ago....same thing, ethanol fouled the diaphram in the fuel pump......238.00 pay out....not to bad. I have since changed every fuel line in the boat and use the Startron fuel additive to combat ethanol issues.

[spareparts]

as far as a service on the four strokes, your looking close to $300 in filters alone(and the gaskets to seal the vst), here lately it seems if you don't do all of them, your right back at the beginning. I swear, I've never seen so many fuel related issues, I had more injectors cleaned in the last 6 months than I had in the last 24 years(yes I know, they weren't fuel injected back then)

[THEFERMANATOR]

I didn't do the VST as he has good pre-filters on his engine. Just the basic annual was all I did. The parts came out to about $200 of that though.

[Blue_Runner]

Phes, cool deal....I would love to change all my fuel lines before it becomes a problem.

Ferm - I'm so used to B.O.A.T (bust out another thousand) every time I have a problem that the $200 seems like chump change....he did lubricate my trailer jack and coupler. Also sprayed down the engine with 656 lube. He said it is a good idea especially if run in saltwater because eventually things will start sticking.

Spare - I would love to have a 4 stroke. The fuel savings would counter the maintenance costs but it would take a long time to justify the price difference from what I paid for my 2 stroke. I would get at least 1 more mpg. I get 2 - 2.5 now. With a 4 I should get anywhere b/t 3 - 4 mpg. Would add a little more weight on my girls donk-a-donk though. Which could make the scuppers angry.

MJ - OUCH! But had to be done! Been there done that...bought 2 t-shirts!

RW - thanks!

[macojoe]

I was told, Right or Wrong?? that the VST system should be done every year if I go 100 hours or every 2 years if I under a 100 hours a year.

or the fuel pump can die and the mariner gets $900 for a new one! They charge $200 to do the VST serves and that also is to clean the lines and injectors and VST tank.

I will do every 2 years and hope for the best.

Do you guy remember when I could not afford a use crap motor!:head:

[Blue_Runner]

I seem to recall a certain fiasco concerning a "used crap motor" that I'm sure both you and I would rather forget.
:cen:

[wwatterson]

Try this troubleshooting procedure. Disconnect the fuel supply hose at the engine. Connect it to a clear plastic hose then connect the other end of the clear hose to the engine. Start the engine and look for signs of air bubbles indicating that you are sucking air somewhere vice solid gas. I used this procedure before to find the same problem. My problem was the clamp holding the vaccum hose to the pulse limiter on the crankcase had come loose. I did not have enough vaccum at high speed to suck enough gas to the fuel pump(in my case not enougn vaccum to the VRO) when trying to get on plane. If you see air bubbles then troubleshoot from there. Also try an external tuel test tank also with a clear hose to eliminate your built in fuel tank and hoses an a source of the problem.

wwatterson
1987 Wellcraft V20 Fisherman with original Sea Drive

[spareparts]

used to be, you hardly every went into the VST, now it seems like an anual occurance. I've all kinds of rumors about whats causing teh trash and why it gets past teh filters, best thing to do is runa good water separating filter, and change it often. I've seen some shops install a suzuki high pressure filter between the vst and the injector rail, it seems to help

[THEFERMANATOR]

Try this troubleshooting procedure. Disconnect the fuel supply hose at the engine. Connect it to a clear plastic hose then connect the other end of the clear hose to the engine. Start the engine and look for signs of air bubbles indicating that you are sucking air somewhere vice solid gas. I used this procedure before to find the same problem. My problem was the clamp holding the vaccum hose to the pulse limiter on the crankcase had come loose. I did not have enough vaccum at high speed to suck enough gas to the fuel pump(in my case not enougn vaccum to the VRO) when trying to get on plane. If you see air bubbles then troubleshoot from there. Also try an external tuel test tank also with a clear hose to eliminate your built in fuel tank and hoses an a source of the problem.

wwatterson
1987 Wellcraft V20 Fisherman with original Sea Drive

Using clear hose to look for air bubbles isn't the best test anymore. With E-10 fuel it can generate air bubbles in the fuel on a hot day now.