silverbullet87

Yea I was watching your thread as well. I'm just a little apprehensive about opening up the mystery filter pump. It looks like something that shouldn't be messed with although everyone seems to pull it apart to replace the basket filters. I'm sure i'll get to that when nothing else works. (I actually have the filters ready to go)

My plugs looked like shit btw - but they looked the same for both motors.(one runs like a champ) They were black and gummy. Swapping them didn't change anything. I was almost positive the motor would run better after swapping but no luck.

Checking the metal canister filter today - and the 02 sensor and i'll go from there. YDS probably won't be here until next week.

hevans

Do you use ring free in your fuel? If so for how long? I would buy new plugs all the way around, you are going to need them in the end anyways.

Pull all 6 plugs on that motor, soak them in seafoam over night - clean them with a wire brush then wipe them with a towel and carb cleaner and let dry. replace the plugs and see what that does for you. My motor would run better - not 100% after doing this. I was able to get about 3900 rpms rather then the 2500rpms and then they would foul out again. I recommend using recycled plugs that way you don't ruin your new set. Save the new set for once it is all figured out. I cleaned my plugs up, reinstalled them and ran the dog shit out of the boat blowing any carbon I could out - rinse and repeat. It really helped the boat run better, she wasn't running perfect until I changed the filters on the HP pump and the injectors. I got my HP fuel pump serviced by a mobile master tech for $200 per pump and injectors at $25 an injector.

silverbullet87

Sometimes it will cut at 1800, other times 2500 etc. It really depends on the engine load. If I work the starboard motor hard to get it on plane - I can get the port motor close to 3500 but it's just relying on the starboard to do all the work. (no load) It basically feels like when it demands more fuel - it's not there. At low engine load though - it sounds perfect. Run both motors at trolling speed and they are purring.

When the bad motor cuts out - it shakes quite a bit and falls on it's face.

hevans

This was my identical problem. The RPMS were never spot on when it would fall on its face, sometimes 1800, other times 3500 change the plugs start the boat and immediately gas it, spend very little time idling as that will foul the plugs quickly. See what this does for you. I was able to get the boat on plane and just kept driving it around on plane for about half an hour, the plugs got better and better and eventually resolved its self once the carbon was blown through. It really ran perfect (back up to 5300RPMS with fishing load) after I changed the last 2 filters - before that I was seeing 5000RPMs after the repeated plug changes. You can actually see your plugs cleaning up with each change. I had about 3 sets of recycled plugs I took on boat with me.

silverbullet87

I replaced all 6 plugs in each motor yesterday and took it for a spin w/ the same results. I am using ring free - but remember these motors only have 100hrs on them - and 50hrs where from the previous owner. (just got the boat last season) So the previous owner only did about 50hrs over 4-5 years. I've run maybe 500+ gallons through them (rough estimation) all using ring free. (some tanks were ethanol). Right now i'm using non-ethanol marina gas. I appreciate your advice btw.

I'll see if i can take some plug pictures etc tonight - make this thread more visually appealing haha.

TUNAHUNTER197

Always check the Low Pressure ("LP") fuel pump's first, easy check and its free....they are the octagon looking pumps after the clear bowl filter, but before the VST. Should be two LP pumps for your 200 hpdi. Unbolt the pumps have someone give the fuel ball a few pumps and see if fuel is leaking out the back of the diaphragm. If so, that is your issue, replace the pumps, $40 each, if not re bolt and move upsteam of the fuel system, which is VST, than silver bullet canister filter, injectors, then HP fuel filers (mystery filters). Good luck, easy engines to work on.

Do both engines run off the same fuel tank? If so, then you can most likely rule out water in your fuel since only one engine is acting up. You should have dumped your fuel/o2 separator into a clear canister and let it settle for a bit to see if you have water in your fuel.

silverbullet87

I did check the LP's. They were both good and pumping fuel into the VST tank w/ no issues. I started there - then went to the VST etc.

Both engines do run off the same tank. Yea i don't think it's a water issue.

silverbullet87

Gotcha. I'll also check the fresh plugs I put in yesterday and see how they look. It just doesn't feel right to driving around at a significant RPM when i feel like i'm lacking fuel but I hear ya.

TUNAHUNTER197

So its either the VST or the silver canister. At 90 hours there is now way the mystery filters have crapped out. Those are typically a 500-1000 hr maintenance item. How old are the engines to only have 90 hours...makes me think the boat sat for a long time and it might be bad gas, just a thought. I would also suggest getting a fuel pressure gauge and attaching it to the VST shroder valve to make sure you are always getting 40-50psi (from when you turn the key on to when the engine crapp's out). If you are getting 50psi keep moving upstream.

hevans

The master tech was on the boat with me. If the boat indeed picks up some rpms then drive it around, if it makes no changes when you change the plugs move on.

Mine would act like nothing happened when I put fresh plugs in. Rpms would be right back up to 4000cruising, the minute I touched the throttle down at all it would foul the plugs and put me right back at square one, falling flat on its face.

In the end, I replaced all the filters. Racor, bowl filter, VST filter, canister filters, Mystery filters and Injector filters as well as all of the LP fuel pumps. I wouldn't consider any of those things a waste of money and the master tech said the canister filter needs to be changed every year and the other filters every 3 years with average use.

I know this is frustrating and a headache, heck I lost sleep over it after purchasing a boat and getting it back home to run like asshole. Might be worth your time to just bite the bullet and get a mechanic involved or get prepared to open the HP fuel pump and injectors. The only good thing about it is you learn the fuel system on these machines.

silverbullet87

I haven't checked the silver canister - doing that today. The motors are 2010's and certainty sat a lot for the past 5-6 years. The boat holds 200 gal of fuel and i've run them through several times this season. (both motors run off the same tank) Good idea on checking fuel pressure.

silverbullet87

Yea i hear ya... I'll just keep going until I figure it out. As you said - I like knowing how the motor works so I can fix issues when they arise in the future.

Weird - I didn't have the same reaction w/ fresh plugs. I got no RPM from the start.

silverbullet87

I replaced the canister filter today with another similar FRAM filter I had available for testing. The filter I replaced seemed very clogged - to me at least. It was hard to blow through - like blowing up a small balloon. I also poured fuel through the inlet and it wouldn't even drip out the other end. I assume thats not normal for this filter. Must be gummed up pretty bad. The feed hose looked good though.

I'm going to take it out at some point this week and see how it does. I also took a pic of the nasty plug i pulled and i'll post it in the am.

skfishing

You are likely going to have to clean the entire fuel system. Make sure the fuel in your tank is clean and change all the filters including the hp "mystery" filters and the injectors. You might see some improvement changing just the cannister, but to be that restricted, its likely all of them. My mystery filters were completely clogged with only 45 hours on a 2005 motor.

skfishing

Your motor is not stumbling because of fouled plugs. It is stumbling because the air to fuel ratio has reached the point where it will not burn, which will quickly foul the plugs. If your fuel restriction is primarily the cannister and mystery filters, all cylinders will misfire together at the same throttle setting, pretty violently, like a backfire. Then the engine will pick back up at a much lower rpm. The stumbling implies to me that some cylinders are getting more fuel than others and your injector filters are part of the problem. Also, you still may have a pump issue, but you need to clean all the filters first.

hevans

What did your hose look like between the VST tank and canister filter? Mine was soft, and left black ink all over my hands. I swear it was the culprit of my clogged canister filter with how clean my VST tank was compared to the canister filter. Its a very cheap and easy fix, new hose is less than $1 and replace any hose clamps with oetiker clamps - maybe a 5 minute change out that could save you a lot of headache down the line.

silverbullet87

Here is the plug. Pretty gross.

silverbullet87

Yea i'm sure i'll be swapping those next. I'm going to give it a run and see if replacement of the metal canister makes any difference to at least know i'm on the right path.

silverbullet87

The hose looked fine - nothing unusual, but i swapped it anyways because i needed a slightly longer hose length for my replacement filter. I have worm clamps on there now just for the ease of testing - and i'll swap those out for oetikers once i'm done sorting problems.

silverbullet87

I was able to fix this issue over the weekend.

The issue was indeed the clogged metal canister filter. (so clogged you couldn't blow though it)

My YDS arrived - and it is well worth the money. (cheap on ebay) I checked the previous data logs (graphs) prior to taking the boat back out for testing - and it showed a very large drop in fuel pressure when under heavy throttle. (this is what i was expecting to see) I took the boat out for a rip and it performed flawlessly. When i was done I checked the new data log and fuel pressure held solid regardless of throttle position.

Full throttle both motors got to 5,000 rpms. YDS tells me that these motors have never seen over 5,000 rpms in their 100hr life - so it seems they are running close to optimal. At 5,000 rpms I need perfect conditions anyways or it's a violent ride so i'm happy w/ how it's running.