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BF175 losing fuel prime

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aliboy

Advanced Contributor
We have a pair of BF175's (2007 models) on a power cat. One of them has suddenly started to lose it's fuel prime when sitting idle. If you pump the primer bulb it will start and run fine. If you stop and restart again within 30 mins (maybe even longer) or so it will again start and run fine. Leave it sitting for an hour (could be a bit longer) or more and you need to pump the fuel primer bulb hard again. Primer bulb is soft when you first try to pump it after the engine has been sitting. Any thoughts?
 
My first rule when working on my cars, trucks and boats...start with the cheapest, most obvious repair, then move on. Replace your primer bulb. I guess it might be something more complicated, but that seems like the most obvious, cheapest thing to replace.
 
Are your primer bulbs pointing up? They should be. The out flow side should be higher than the inflow side.

If so, then it's likely that the check valve in the primer bulb is not sealing well, so change it out. And if you replace one, you probably ought to change the other one.
 
Also starting at fuel tank check security of all hose clamps, fuel lines are 10 years old they should all be replaced "ethanol"?
 
My first thought was the primer bulb but it pumps up hard when you squeeze it, so I assume the valve in it is ok? I will change it out anyway as the most likely suspect. What is strange though is the on-engine filters (the clear bowl ones) appear to stay full. No ethanol ever on this boat so it isn't ethanol related.
 
Question - once you turn on the key and hear the two beeps, how long do you wait before you crank the engine? You should wait 2 or 3 seconds to give the HP fuel pump time to pressurize the system. Over time, the fuel pressure in the fuel pump housing and the VST will drop even when everything is operating correctly.
 
We have around 10 years and 2000+hrs on these engines so this is definitely something new rather than an operation issue. The very strange thing is that I went back to the boat yesterday to do an engine flush and the damn thing fired straight up. Now I will have to wait for it to reoccur before I can carry on diagnosing. The primer bulb seems obvious but the one problem is that when you pump it up it goes hard just like it should. A bad valve shouldn't let it go hard. Will update this thread once I get it to reoccur and can look into it further. Meantime, thanks all for the help.
 
As you well know those intermittent problems are the hardest to diagnose. I think your 175's are set very similar to my 225. A few weeks ago I posted a list of screens and filters that should be regularly checked, especially if you are having fuel feed problems. I'll try to post again, below...

• LP fuel filter 16901-ZY3-003
• HP fuel filter screen 16911 ZY3-010
• Fuel Pump Filter 16911-759-003 (on top of VST)
• Suspension strainer 16915-ZW5-000 (over top of fuel pump filter)
• Fuel Pump Insulator 16718-ZY6-013
• Fuel filter mesh 16614-P5G-003

Note: Fuel filter mesh 16614-P5G-003 is on the fuel rail. Item #4 as shown at…
http://www.boats.net/parts/search/H...er/BF225AK0 XCA/FUEL PIPE INJECTOR/parts.html
 
Thanks CHawk. The engines were serviced including the HP filters etc a few months ago by a Honda Tech. I will get hold of hi and find out what else he checked and then have a look at your list. The 175's are the same block etc as the 225's but no Vtec on them. I often reference the more common 200 and 225 links as there aren't so many 175's around.
 
I suspect you have the same filters on your engine. The VTEC operation is not affected by the fuel filters to the best of my knowledge. Over the years on this forum there have been difficult-to-diagnose problems caused by dirty or clogged filters that are not well addressed in the Helm shop manual, especially the suspension strainer and the fuel filter mesh - items 4 and 6 on the list above.

You can paste those part numbers in the search box on Boats.net, it will take you to the part, and from there it will take you to the parts diagram so you can see exactly where they are.
 
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