4 strokes and primer bulb issue?

[th365thli]

Hi all, I had something kind of strange happen to me today. DF200SS 4 stroke.

I was running around the lake and fishing. About 3 hours into the day, As I was getting on plane, I lose all power the engine goes all the way down to 0 rpms and shuts off. I then hear 3 beeps. Concerned, I checked my C10 gauges for any codes thrown. No codes thrown. I then checked the history. None in the history, none active. This was really peculiar to me. Moreover, I couldn't find anything on my phone about 3 consecutive beeps

I then tried starting her again. She turned over fine, idled for about 5 seconds, then died. Same 3 beeps. No error codes. Called some buddies. Tried starting her again, this time she cranked up but then died almost immediately. My buddy with me remarked that it's acting like it's running out of fuel. This was also confusing since I was 100000 percent sure I had fuel in the tank (22 gallons to be specific).

After calling some friends (no dealers open on Sunday), one person suggested to check the primer bulb. Now, seeing as this is a modern 4 stroke, I thought primer bulbs were unnecessary. But I checked the bulb and it seemed empty. I squeezed it and didn't feel any fuel. So I tried priming it. It was difficult to prime, but eventually I got it hard. Started the motor. Viola, it runs perfectly. I cautiously take it up to plane and ride to our next spot. After fishing for a while, I start the motor again. I get on plane, and after cruising for 10 seconds she drops rpms and dies. We check the primer bulb. Flat, or if not flat, then at least devoid of fuel. Squeeze her up to firmness. Decide that we should probably head home. After firming the bulb we cruise to the ramp without issue and load up.

This makes me curious. Modern 4 strokes don't need to be primed constantly, certainly not before every run. How should I go about diagnosing this? And besides what I said here, what relevant information should I tell my dealer? I was able to idle fine after pumping the bulb, certainly long enough to putter to the ramp and load up the boat. Is it a faulty primer bulb, a faulty low pressure fuel pump, or something else? I somewhat doubt it's a fuel pump issue since we're able to run fine after pumping up the bulb. Plus, no error codes thrown, engine dies at all sorts of rpms.

Just a really puzzling case.

[Murray]

https://www.suzukioutboardforum.com/...-used-at-speed

Here is one of many, upper right hand corner search “primer bulb” Give you some reading material

[Triton2300]

https://www.thehulltruth.com/boating...uel-issue.html

i would hook up an external tank, hose, and primer ball to start eliminating things outside the engine. The only thing I can find on the three beeps is oil change time. Ethanol fuel can eat fuel lines causing blockage in the engine.

[2014DF25ARS]

I don't know what the technical requirements are for the primer bulb on a 4-stroke motor. I've never heard that it's any different than a 2-stroke, except for the older 2 strokes that used pressurized tanks.

But I will point out that I did have a similar problem with the bulb on my DF25A within a year of getting the motor. After some troubleshooting, I replaced the bulb and cut the old one open. What I found was that there is a plastic check valve at each end of the bulb, same diameter as the hose fitting. One of the valves had come loose and was floating around in the bulb. After the fact, I realized that I could feel the loose valve through the rubber if I squeezed the bulb flat. With that experience, I would suggest you try the same: pinch the bulb flat between your fingers and see if you can feel something inside the bulb. If you do, replace the bulb! I was skeptical that such a failure could occur with a new motor, but in my case it did.

I will also point out that the high-pressure fuel pump in a fuel-injected motor relies on the flow of fuel to cool the pump. A Suzuki mechanic told me that I could destroy the high-pressure pump by running the motor dry at the end of an outing - which for many people is standard practice with carbureted outboards. I don't have any proof, but based on my experience I have a hunch the computer will shut down the motor if the high-pressure fuel pump does not have sufficient input fuel pressure, to save the high-pressure fuel pump.

[th365thli]

I don't know what the technical requirements are for the primer bulb on a 4-stroke motor. I've never heard that it's any different than a 2-stroke, except for the older 2 strokes that used pressurized tanks.

But I will point out that I did have a similar problem with the bulb on my DF25A within a year of getting the motor. After some troubleshooting, I replaced the bulb and cut the old one open. What I found was that there is a plastic check valve at each end of the bulb, same diameter as the hose fitting. One of the valves had come loose and was floating around in the bulb. After the fact, I realized that I could feel the loose valve through the rubber if I squeezed the bulb flat. With that experience, I would suggest you try the same: pinch the bulb flat between your fingers and see if you can feel something inside the bulb. If you do, replace the bulb! I was skeptical that such a failure could occur with a new motor, but in my case it did.

I will also point out that the high-pressure fuel pump in a fuel-injected motor relies on the flow of fuel to cool the pump. A Suzuki mechanic told me that I could destroy the high-pressure pump by running the motor dry at the end of an outing - which for many people is standard practice with carbureted outboards. I don't have any proof, but based on my experience I have a hunch the computer will shut down the motor if the high-pressure fuel pump does not have sufficient input fuel pressure, to save the high-pressure fuel pump.

Thanks for the detailed reply. I've posted this question in other forums and other people suspect it's the check valve as well. Here's what I suspect is happening:

Check valve fails causing fuel to drain back down. Turn the key. Low pressure fuel pump is unable to draw fuel all the way from the tank. There is still fuel above the check valve. The engine is able to use that fuel to run normally. However, it gets used up quick especially when running on plane. Once the fuel is used up, the engine shuts down to protect itself. I think the engine definitely shuts itself down because it doesn't sputter or stall, it just cuts rpms smoothly down to zero, shuts off, and beeps. That sounds to me like a guardian mode. I'm crossing my fingers that it's just a simple primer bulb issue. Especially since when it does run, it runs fine, no loss of power or rpms.

[artdf175]

I put a note on another post not too long ago but don't find it now
What happened is almost exactly what you describe
To make the story short - the crimps on the primer bulb were failing or the rubber shrinking but air was getting around the nipples that the fuel hose attaches to
so when running it was sucking air causing limits to rpm but when turn off the fuel drained back to the tank requiring a lot of pumping to get fuel back to the engine
replaced the bulb and problem solved
Art

[Moonlighter]

All of this is pointing to a restriction or related problem in your fuel system.

A primer bulb that sucks flat is a sign of fuel not getting thru the lines to the bulb. Nothing to do with the engine. The fact that the bulb is sucking flat is indeed a sign that the electronic fuel pump is doing its job perfectly. It just cant suck fuel thru because there is none getting to the bulb....

The alarms you are getting are probably just an indication that it has starved out of fuel.

So apart from the primer bulb itself, which I am not so sure is the problem from what you have told us, there are some other common FAIL POINTS prior to the bulb to check and address as required.

1. Fuel filter. I will assume you have a water separating fuel filter in the fuel line? Drain it and change the element. If you have picked up a dirty load of fuel and its 90% blocked the filter, pumping the bulb can often get enough fuel thru to run at low revs a short while. I had this happen a few years ago was very similar to what you experienced. Drained the filter and saw signs of contamination in there so changed the filter element. Then changed it again 20 hours later to make sure that I had got most of the contamination. No problems since.

2. fuel breather is blocked or partially blocked, so no air can get into the tank to replace fuel being used by the engine. Check that air can flow freely thru the breather to the tank. Take the fuel filler cap off and blow air thru the breather outlet.

3. another thing to check is the anti-syphon valve on the fuel tank. They are WELL KNOWN to fail and cause the same kind of symptoms you have found. I personally would just take it out and replace it with a straight thru barb as its really not serving a useful purpose on an outboard powered boat.

4. fuel lines themselves. Flex the lines they should be soft and pliable, if there is any feeling of crunchness when you flex the lines around, then the interior lining has collapsed (possibly due to ethanol fuel and incompatible lines) and is blocking fuel flow and also is likely to have gummed up the inline filter. Replace bad fuel lines and filter element if that is the issue.

5. If f that all checks out and the problem still persists, the fuel pickup in the tank could be getting clogged up with gunge. They usually have a fine mesh filter on the end. They can usually be removed for inspection and cleaning/replacement, and you then would need to address the garbage in the tank that is clogging it. Might mean having the tank drained and cleaned and the fuel “polished”.

[th365thli]

Thanks for the responses everyone. And thank you Moonlighter for the extremely detailed response. I'm not convinced it's the fuel filter since I'm able to run at all revs. Once I prime the bulb the outboard runs very well, as if nothing is wrong. The boat is also very new, so while I'm not ruling out your points about the fuel lines, i'd be pretty annoyed if they were wearing out.

I dropped off the boat at the dealer today. They were pretty diligent about asking questions and taking notes. The lady told me to not speculate, they'll go over it haha. I'll take her advice to heart and try to manage without fishing for the next few days.

[th365thli]

Well the dealer called today and he believes it is in fact vapor lock. He tested the engine and even ran the boat on the water a couple times but could not reproduce the issue. As an engineer myself (albeit software), I know how frustrating intermittent problems can be to debug.

Apparently this was way more common in the lower horsepower inline 4s, but it's not outside the realm of possibility for my case. He said it tends to happen when temperatures are just right. It's not uncommon to see it happen when air temps start to really warm up, but water temps are still cool. He also said it could possibly happen late summer / early fall as well. Something about temperatures having to be just right. At any rate, he told me to run it, and if there's still an issue to bring it back. He also told me turning the engine off immediately after hard running can cause it. So i'll try to idle more after a long WOT run.

[Moonlighter]

A vapor lock in the VST etc is not going to suck the primer bulb flat..... think about it - the primer bulb lets fuel in one side and passes it out the other. It has a check valve that should prevent fuel running back out the inlet side.

The only way it can be “sucked flat” is if fuel is being drawn thru the outlet side and none or insufficient is coming in the inlet side.

So being a fairly new boat, the likelhood of fuel lines deteriorated is low.

So that leaves 3 main options - a dirty load of fuel having partially blocked the inline fuel filter, a blockage in the fuel tank’s vent line. The vent line is easy to check yourself. Mud wasps like to build nests in the outlet ..... the third option is a air leak in the fuel lines but that would typically leave the bulb soft and empty, not sucked flat. Tightening up every clamp between tank and engine is fairly easy to do and is something that should be in the annual check list as well.

Draining the inline fuel filter and changing the element is a simple job and is something that should arguably be done once a year anyway.

For the cost of an element its well worth doing. Really nothing to lose by doing it. You never know when you might have picked up a load of dirty fuel.

To be 100% clear I am talking about the RACOR style water separating element that is in the fuel line between fuel tank and the primer bulb.

I had almost the exact same symptoms as you a year or so ago and yes it was on hot sunny days, but after the filter element was changed, no more issues.

Another point re the vapor lock theory - if that was the problem, when it happens, you could turn the key off, turn it on again, wait for the beep to finish, and the LP pump then primes the system again and that would eliminate the vapor lock. You might have to do that on/off twice to ensure the system was fully primed. The engine should then start. If it doesn’t start and run fine, then the vapor lock theory is very doubtful.

[th365thli]

A vapor lock in the VST etc is not going to suck the primer bulb flat..... think about it - the primer bulb lets fuel in one side and passes it out the other. It has a check valve that should prevent fuel running back out the inlet side.

The only way it can be “sucked flat” is if fuel is being drawn thru the outlet side and none or insufficient is coming in the inlet side.

So being a fairly new boat, the likelhood of fuel lines deteriorated is low.

So that leaves 3 main options - a dirty load of fuel having partially blocked the inline fuel filter, a blockage in the fuel tank’s vent line. The vent line is easy to check yourself. Mud wasps like to build nests in the outlet ..... the third option is a air leak in the fuel lines but that would typically leave the bulb soft and empty, not sucked flat. Tightening up every clamp between tank and engine is fairly easy to do and is something that should be in the annual check list as well.

Draining the inline fuel filter and changing the element is a simple job and is something that should arguably be done once a year anyway.

For the cost of an element its well worth doing. Really nothing to lose by doing it. You never know when you might have picked up a load of dirty fuel.

To be 100% clear I am talking about the RACOR style water separating element that is in the fuel line between fuel tank and the primer bulb.

I had almost the exact same symptoms as you a year or so ago and yes it was on hot sunny days, but after the filter element was changed, no more issues.

Another point re the vapor lock theory - if that was the problem, when it happens, you could turn the key off, turn it on again, wait for the beep to finish, and the LP pump then primes the system again and that would eliminate the vapor lock. You might have to do that on/off twice to ensure the system was fully primed. The engine should then start. If it doesn’t start and run fine, then the vapor lock theory is very doubtful.

I definitely see what you're saying. The problem is, I can't remember if it was "flat" or "empty". I think it was more "soft", not completely flat as if an invisible hand was squeezing it. I will verify when I run it again soon.

The other issue is, the mechanic couldn't reproduce the issue. Now, there is a possibility they're all liars and they didn't actually run my boat on a lake like they said, but I have to operate with some good faith here, especially since they are a reputable, Suzuki service award winning shop.

I will certainly check/replace the water separator filter, as well as check the fuel connections. I'll also turn the key on/off a couple times to ensure the LP pump primes the system properly. Lots of things to try here.

Do you think the primer bulb being mounted flat has anything to do with it? It's always been mounted flat since I bought it.

[Moonlighter]

The primer bulb works best when it is positioned with the end closest to the engine upwards. If you can position it like that it helps the check valves to work.

Is the primer bulb a genuine Suzuki one or an aftermarket one? Many of the aftermarket ones are poor quality and check valves and connectors at each end are known to fail. The OEM Suzuki, Merc and Yamaha bulbs are much better quality. But occasionally they do fail too.

[th365thli]

The primer bulb works best when it is positioned with the end closest to the engine upwards. If you can position it like that it helps the check valves to work.

Is the primer bulb a genuine Suzuki one or an aftermarket one? Many of the aftermarket ones are poor quality and check valves and connectors at each end are known to fail. The OEM Suzuki, Merc and Yamaha bulbs are much better quality. But occasionally they do fail too.

Well Moonlighter, your expertise is still proven. I took the boat out today and the same thing happen. At first key turn of the day I was able to run for 10-15 minutes to my first spot. I fish for maybe 10-15 minutes, then go to my second spot. I fish there for a couple hours at least. Then, as I start my run back to the ramp it does the same thing, cuts rpms to 0, shuts off, 3 beeps.

Turns out my dealer/mechanic misunderstood me, when he ran it he didn't cut it off and run it again. He just ran it for a time, never cutting it off and restarting. Furthermore, it seems like to reproduce the issue a period time needs to be present between first crank and second crank. After fully explaining the issue, he said it could be the bulb, fuel demand valve, or anti siphon valve. He didn't mention anything about the fuel filters. My tank is a newer tank and doesn't have vents. The new style tanks are pressurized and the vents are in the gas cap. Don't see how anything can be blocked there.

This is pretty curious issue. The confounding factor is that it works on the first crank of the day. I didn't prime the bulb this morning when I took the boat out. My plan is to change out the water separating filter and primer bulb, replace with an OEM quality bulb, and take it from there.

[th365thli]

Also, mechanic and I agree that if this issue is able to be reproduced, then it's most likely not vapor lock (should've listened to you the first time Moonlighter!)

[Moonlighter]

Ok see how that goes.

It doesn't sound typical of an anti-syphon valve failing, but it does no harm to remove it anyway, they are just a “problem waiting to happen” in my opinion. They are never fitted to fuel tanks on outboard powered boats here in Australia and nothing bad happens as a result.

A mate imported a US boat a few years ago (Seaswirl Striper) and a couple years later, the anti syphon valve failed and the engine would stall after running at speed and then dropping back to idle. I unscrewed the AS valve from the tank, took it to the workbench and punched out the little ball spring and seat from inside it, leaving a straight through barb. Refitted it to the tank and reconnected hoses. Problem solved.

Good luck I think you are on the right track.