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2004 Honda 150 vtec VST drain location

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Shaun W

New member
Hello. I’m new here but have already gotten great information from older threads. New owner of an old 2001 Proline 19 sport with a 2004 Honda 150 VTEC that I’ve been tuning up. New to boats altogether. When I got the boat the motor fired up beautifully and idles like a million dollars but I’ve been troubleshooting the fuel system. I’ve replaced most of the fuel lines. Replaced the low pressure fuel filter that’s right after the water separator. I’ve replaced the high pressure fuel filter that is in the sideways bracket that I believe is right before the VST. With each of these I’ve gotten better fuel delivery and trips on the water. When I eventually replaced that high pressure filter she ran great for several hours but then suddenly would bog down at higher throttle but continued to idle and run at slow speed without issue. I found the new filter crushed inward on one side. I replaced again and good for a few hours but then again started having the high throttle issues. I’ve been reading about the VST possible needing to be cleaned and addressed. I can’t locate the drain screw that I keep reading about. I’ve looked and felt around the entire surface from bottom to top but can’t seem to locate what everyone is referring to. The only screws I see look like the screws that hold the mounting face plate on and those from the top. Any suggestions or does anyone have a picture of what I should be looking for? Any help would be greatly appreciated.
 
Hi Shaun,
I've not worked on a 150 but I see there's a drain screw with oring available.
Problem is though, it's not clear where it's exact location is in the parts diagram. Item 8 in link.


II would think it's gotta be near the bottom of the tank.

Sorry, but that's all I can offer for that.

As to your fuel starvation issue, the collapsed fuel filter makes me think there could be a restriction on the inlet side of the filter housing. Again, I've never worked on one of these so just guessing here. But item 9 in the link that includes item 38 caught my attention. And, although it doesn't appear associated with the filter, item 53 makes me scratch my chin and think "hmmm, I wonder"?

You might also want to check for a soft spot in item 30 in link below that could cause it to collapse.


I don't know, but sometimes on fuel rails there are screens that catch debris to protect the injectors. Just guessing, but the fact that there are two "fuel joint" fittings that have different part numbers might indicate one of them has a screen inside. If so, that could be a spot for a clog. Items 8 and 9 in link below.


Good luck getting her dialed in.
 
Thank you. Thats actually helpful even though it’s not real clear on the diagram. If it threads down on the side that it appears to show it aiming towards maybe I can find it. Thank you for the diagram and help! I’ll take another look later when I’m home. I’m going to attach some photos in case someone else might know where it’s located.
 
Also, is it possible that the high pressure fuel filter is collapsing due to not being a genuine Honda filter? I know it’s always recommended to use Honda parts but could it actually collapse and cause a fuel retraction after a few hours of use simply because it’s a cheap aftermarket product? I’ve already ordered a Honda filter to replace it with but I’d hate to keep destroying $50 filters attempting to troubleshoot the problem.
 
Something else I noticed is that there appears to be a drain hole at the bottom of the high pressure pump housing. Item 18, oring, in the first diagram I sent is depicted next to it but, again, no clear explanation as to what it seals and there's no drain screw pictured there. So, I don't know. Maybe that's where they drain the whole she-bang?
Notice that the quantity for item 18 is 2.

They didn't do us any favors for trying to figure it out, that's for sure.
 
You should get the Honda factory manual for your outboard, don’t bother with anything but the Honda manual.

My pet peeve with boats/outboards when they are not running well is fuel tank/fuel contaminants. How old is your fuel in the boat’s tank?

When you changed fuel filters, how dirty were they? Did you cut them open to check them?

Do you have a spin on fuel water separator filter? When you changed it, did you empty it into a clear glass container to check for water quantity and for dirt particles?
 
I found the VST drain but the release screw was badly corroded and stripped. I was able to remove a hose that runs from the bottom of the VST itself to this side bracket where Honda made it “convenient” to drain. Once I was able to remove the small hose I immediately got fuel pouring out of the VST. I filled a mason jar 2/3 of the way and after some time the was no water separation and the fuel looked clean with no sign of sediment or anything.

I currently am running off of a brand new 12 gallon external tank as I work on cleaning out the boats interior tank as that was a major problem when first getting the boat. I replaced the bilge area water separator which had a broken bracket and badly corroded. In my ignorance I thought all water separators were the same and have been running the boat on the new one. Initially I siphoned out 20 gallons of new ethanol fuel that I had filled into the interior tank after I drained it of all of the old fuel I could thinking I had fixed that issue. When the tank still posed issues with fuel delivery even after a new sending unit and pickup tube I bought the external tank to try and she ran amazing initially. I also replaced both fuel fingers in the motor with inexpensive new filters. After a few hours of running the boat with no issues it started bogging down at high throttle. No alarms. No issue when idling or running low speed. I dumped the bilge water separator and it was 1/2 water. I got rid of the fuel in the lines and replaced with a new canister. That’s when I first noticed the high pressure fuel filter I had recently installed was crushed. I figured it must have been the bolus of water that had made it past. I replaced all the filters again and I checked the fuel in the tank and it showed no sign of any more water. I took it out on the water for a couple of hours. No issues until heading home I could tell it was starting to hesitate at high throttle again. No issues with fuel delivery. Primer bulb stays inflated and has good flow. Not a vent issue on the tank. Today I dumped the water separator again and it was pure clean fuel. Same with the motors water float catch tank too. When I checked the high pressure fuel filter it was again crushed. I suspect this is the cause of the hesitancy at high throttle. As I mentioned before I eventually figured out how to drain the VST and it was clean fresh fuel with no contaminants and it drained instantly and easily. I read that a Honda 150 should be using a 10 micron water separator and the one I installed is a 21 micron. So, I replaced it with a new 10 micron today and I again replaced both low and high pressure fuel filters. That’s where I’m at. I suspect that water was my initial issue but I also suspect that I need a better quality high pressure fuel filter as the ones I’ve been testing with seem to collapse after a shower time. Any more thoughts?
 
A crushed filter would seem like a source of fuel flow restrictions. Bad quality filter? Wrong filter? Too much fuel pressure? Wrong pump?
 
I went ahead and ordered Honda made filters. Waiting for them to come. The cheap filter seems to be the right size and was identical to the old black one I took out when first getting the boat. From the level of effort it took me to get into that filter housing I doubt it was ever replaced.

What would indicate or cause “too much fuel pressure?” The low pressure pump that I can see appears to be a Honda part. The fact that everything seems to run great when the filter is new and not obstructing fuel seems to point me in the direction of the filter being too low quality and too easily collapsing. Does anyone have positive experiences using these cheap Amazon filters? I get mixed when asking around. Is there anything other than the filter itself that would cause the collapse? I should add that when I originally removed the old blackened filter it was dirt as all hell but it wasn’t collapsed.
 
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