Delayed Start Question

[CCfishing]

2017 Mercury Pro XS
Serial: 2B361294

Hey Guys,

Throughout the day my motor will randomly take about 3-4 extra seconds to start (but would always start). Definitely something that has not been normal. I changed my fuel filter-still happened. Couldn't figure out what was causing this to happen, so I brought it to my mechanic. He was also frustrated as he could not determine the issue either and he couldn't get the starting issue to happen.


After I picked it up, I went to the ramp and went to prime my fuel bulb and it was not collapsed, but just empty inside. It look about 20 pumps for me to start to get fuel in there. I noticed before I would start the engine each time, that about 90% of the time the bulb had no fuel in it at all...this seemed to be when it would take a few extra seconds for the motor to turn over.

Is the fuel bulb supposed to stay hard the entire day of fishing?

I ordered a new Mercury bulb...could it just be one of the valves inside the bulb are damaged and it is causing fuel to go back towards my fuel tank??

Is this why I am getting a delayed start?

I appreciate your time and help!

Chris

[leonreno]

Could be a bad bulb, bulb will not stay hard all day but it should stay full of fuel. The motor suck the fuel out of the bulb/tank so it’s under slight vacuum when running. If the valve inside is bad then all the fuel in the hose could empty back into the tank.

[lpugh]

Twenty pumps would indicate to me the VST is empty indicating it is leaking while setting, check it carefully for any leakage after pumping the bulb until it is full trimmed level, Fuel pumps can not pump fuel with a empty VST! The main reason that Mercury recommends pumping the bulb before every start, Should not take more than 2 to 4 pumps of the bulb to become firm unless it has been not used for an extended period of time. There are other factors that could cause this such as temperature, elevation and fuel quality, Check for leaks first, esp, the water in fuel sensor in the front lower of the VST and the drains
The bulb will always require one or two pumps under perfect conditions to be firm, that is normal
Make sure the arrow on the bulb is pointed upward with less than a 45 degree angle, I secure all of the ones I install in this manner as it does help a great deal in assuring a vapor bubble is not trapped there, On ones that are in the splash well I relocate them to the bilge out of direct sunlight
2017 probably has a fuel on demand valve that could be a factor in this as well, some have had issues with them
You may have warranty protection for this
Don or Joe will probably be along soon to add to this I'm sure, those guys are really busy this time of year

[EuropeanAM]

Factory warranty has ended- there is a Platinum Product Protection Plan (does not cover rubber/plastic components, however).

As suggested, you likely have an AIR LEAK somewhere in the fuel supply system. Primer bulb and line from bulb to engine are pretty straightforward to replace (OEM ONLY). Then also need to check from bulb back to tank for loose connections, loose fittings, broken components, etc.

[CCfishing]

Thanks so much guys...will replace and report back. Your time and help is greatly appreciated!

[CCfishing]

Going start with changing my ball out first thing in the morning..then plan on running the boat and see if this delayed starting issue continues.

I did inspect my fuel line and connections...didn’t see any signs of a leak. If this issue is an air leak would I still be able to run well at top speed? I have not experienced any other issues besides it taking a few extra seconds to start once I turn the key. Motor runs great at high rpms. Also if it was an air leak would I smell gas? ( have not smelt any)

What’s frustrating is my fuel bulb seems to be getting empty intermittently. Yesterday in the driveway the bulb needed 3-5 pumps and it got hard...did not touch the boat all day today...went out before dark and about 2 pumps it was hard. If it was a broken valve inside the bulb, wouldn’t it always be draining fuel back towards the tank? Last week on and off the water the bulb was not collapsed, but empty several times throughout the day.

If the ball does not fix my issue tomorrow, would my next step to be to replace the entire fuel line?

sorry for all the questions...this is starting to drive me crazy

Appreciate your time and help

[SilverFox579]

Might also have a bad anti-siphon valve at the tank but could also just be nature of the beast with today's fuel, which Don has posted many times, can vaporize in the line at temps as low as 60°.

I'd replace the bulb (OEM only) and anti-siphon valve at the tank then see if it helped.

[CCfishing]

switched out the fuel bulb, ran the boat for 7 hours..engine ran great and did not hesitate at all before starting. Going to keep a close eye on it...hoping this solved my issue...appreciate all the help on here guys

[CCfishing]

Update on this....same issue continues once or twice throughout a fishing day. Nervous this will get worse. After it happened the second time yesterday, motor was running...turned it off and was tough again to get the fuel bulb hard....seems very intermittent that the ball will stay hard, but most of the time it does. No other symptoms at all are occurring...no cutting out and running great at top end. Started the boat at least 25 times yesterday and happened twice (taking few extra seconds to start).

could this just be some type of vacuum lock I am experiencing with the heat? I’ve been popping my gas cap throughout the day...lots of air releasing when I do this...not sure if that can help at all in this situation. Supposed to go to Ontario in two weeks and hate having to worry about this.

[CCfishing]

Is anti siphon valve hard to switch out?

[EuropeanAM]

Bulb does not STAY HARD... the fuel supply line is under VACUUM once you start the engine.

Additionally- fuel in that line tends to vaporize when you shut the engine down, especially in temps above 60 degrees F.

It is necessary to pump the primer bulb FIRM before each engine start to ensure LIQUID fuel is supplied to the fuel pumps (and not vapor).

[CCfishing]

Thanks Don,

having this motor new for 4 years...What would cause this to just begin now?
Could this potentially get worse where I would not be able to start it?
Anything I can do besides pumping the ball firm to help prevent this?

Thank you for your time and help

[SilverFox579]

Is anti siphon valve hard to switch out?

Depends on your tank access.

I’ve been popping my gas cap throughout the day...lots of air releasing when I do this...not sure if that can help at all in this situation.

Are you sure it's air releasing not air being sucked in? A fuel tank under vacuum would match your bulb symptoms. A quick way to check this would be to run engine off a known good test tank.

[CCfishing]

Thanks SilverFox,

I thought it was coming out, but will pay closer attention and confirm next time I pop it.

Is there any fix for a vacuum?

Ive been really paying attention to see if there is any type of pattern when it takes a few extra seconds to turn over, but it has been very random. I started the motor probably 20-25 times before it happened on my last trip. And still happens only once or twice over the course of a 6-8 hour day. Besides that one or two times, it always fires right up and am running top speed with no issues at all.

Any reason why something like this would start out of nowhere?

Will this go away once it cools down?

appreciate your time and help!

[lpugh]

A low or empty vst will not be a drainback problem. If the bulb does pump up in 4 or 5 pumps the vst is not anywhere near empty, 10 to 20 is extremely low or empty. Possible cause for this would be:
Fuel quality and/or high ambient temps
VST fuel leak
Fuel on demand valve
Pulse pump stops working as the rpm comes down such as at idle
Due to high heat from soak fuel in vst will start turning to vapor
Low crankcase pulse for pump to work at low rpm
derbis in the pulse pump or needs rebuild
Suction leak between pulse pump and fuel in the tank
Bulb not mounted with arrow pointed up
I will offer a good reference point to think about:
My 250 pro xs has been setting in the garage for 8 days, lows at night in the 60s daytime 98 to 102 in the garage, last time it ran was idled thu the five an put on the tailor
I Just went and pumped the bulb and is was solid on the second pump, this is always the case on my boat, I have become so confident in this that I never pump the bulb unless I run out of gas or for service or it set without use for 2 or 3 weeks.
I contribute this to 1. the fuel I use . 2. proper bulb placement and hose routing

In your case I feel it is very important to pump the bulb for every single start and count the pumps required. You need to determine if this is caused by low fuel level in the vst or or something else
I kinda hesitated to post what I do because of mercury's advice recommending to pump it every time, Pumping it every time gives you a warning that something is starting go wrong if it requires additional pumps to get solid. It is in fact the best policy to pump it every time

[CCfishing]

Thanks for the feedback...this whole situation is very intermittent making it difficult to identify my issue.

If the vapor is my problem is it normal and ok to experience this issue of a few extra seconds to start a couple times throughout a fishing day? Will this eventually go away when temps cool down?

I don’t get how this just starts this summer and has never happened in previous hot summers.

Is there anything else I can do to prevent this besides pumping the bulb prior to each start?

[lpugh]

BY the best fuel that is available, 10% ethanol (no cheap stuff) is ok. Be sure the bulb is in the bilge area out of direct sunlight, run fuel lines to avoid high and low spot as much as possible. A lot cheap fuels are very unpredictable as to their Reid vapor pressure ratings with no regard to marine use or motors that are carbureted. Keep track of pumps required, if only 4 or 5 pumps, not likely to be low vst level or vapor lock. I would also be checking air/fuel pressure after hot soaks as well

Check and recheck the vst for leaks when setting, that 20 pumps really bother me and if it is a fuel delivery problem with the pulse pump back, I would expect it to start maybe and die, additional cranking time would probably not get the pulse pump to deliver enough fuel to start without pumping the bulb, I could see how a low vst level with a very good pulse delivery could cause this symptom

All this make me wonder about intermittent low & high pressure fuel pump operation

[CCfishing]

I appreciate all of the time and help on here..thank you

This situation has been so frustrating for me as my long time mechanic who I have had so much confidence in has not been able to identify this issue and I am the furthest thing from a mechanic. He is not a “certified” Merc tech, but very knowledgeable and has a great reputation. I did speak with a certified Merc tech from a different marina and was told by him: until the issue becomes more consistent or gets worse there is nothing he can do.

I called Mercury just to get some guidance on how to handle this, but they said it must be seen by a certified Mercury tech before they can send anyone out to look at it, but they aren’t sending anyone out due to covid.

Debating on how to handle this...trying to catch this before I end up stranded or not sure if this is even a major issue....where I should just run it and see what happens since it runs great 99% of the time...just noticing this random hiccup which has not happened previously

I didn’t want to pay another mechanic if he’s not able to identify this since it is so intermittent...just to hopefully have Mercury eventually send someone out.

Should I just run it and keep an eye on it or find a new Merc tech? Don’t want to keep dumping money and not identifying a possible issue.

Wish I could bring it back to my dealer ( bass pro) but they have demonstrated so much incompetence several times since I have purchased the boat from them....

.sorry for the long post and rant

[lpugh]

I don't want to mislead you Chris, I am not a Mercury Tech, I am an Automotive Tech with fair understanding of these motors, I do however have have a better understanding than most on how this stuff works. Anything Don says should carry a lot more weight than my opinion. He has the Factory training and experience I don't have on mercury's, I just rely on a very strong automotive background, what I read in the service manuals, what I gather on this site and 40 years of taking care of my outboards.
If you motor is running well and no power loss, it is not likely you will harm anything, the best thing that could happen is for it to become repeatable. This is really tough for dealers to solve issues like this. Every clue you can gather can be a great help in coming up with the most likely answer

Having Mecr dealer print freeze frame and fault data and posting it hear may be helpful

[CCfishing]

Not at all Leon, thanks so much for your time and helping me troubleshoot. You have given me a great starting point to help diagnose the issue. I agree once this becomes more consistent, it should be easier to find. Just got in a little of a panic because I’ve had a trip planned for a while to Ontario next week and wanted to go with confidence in the motor...not that it’s never not started or anything but didn’t want anything to get worse.

very appreciative of everyone on here who takes the time to respond and help others out. Means so much..thanks guys!