225 HPDI

[Chris225]

I have a 2004 225 HPDI that has started having problems at take off. If I floor it to get up on plane, as the boat is breaking over the engine starts to miss. It feels like it is losing fuel. It will studder and eventually take off and run fine with no other problems. If I take off slowly and keep the boat somewhat level it doesen't do it. I have replaced the fuel filters and checked the plugs and they look fine. I really don't want to put it in the shop ($110 per hour) if I can keep from it. Any ideas?

Thanks
Chris

[BuzzB8]

The last time mine did something like that, I was able to change out the plugs and get it back to normal.

[Chris225]

Well I put 6 new plugs in it, even though the old ones were only 6 months old and its still doing it. It feels like to me maybe the fuel pump is losing presure. I just can't figure out why it is running so good the rest of the time.

[Blaine0311]

I have the same motor and it did the same thing to me today.

It would idle rough like it was missing. Wouldn't throttle over 1600 rpms unless I put it in gear and floored it real quick like. Then just about time it would pick up speed and get on plane it would die back down to around 1600 rpms.

Anyone know a good Yamaha guy in SA? lol

Chris, Let me know if you find anything out and I'll let you know if I do.

[JUST-IN-TIME]

change all filters
clean the vst tank

[Chris225]

I spoke with a yamaha mechanic today and he said it sounds like the fuel level is to low in the VST. He said it is probably either the mechanical fuel pumps or the float level adjustment. He described exactly what it was doing when the motor rocks back. Guess I better save up some more money to put it in the shop.

[Blaine0311]

I hooked the water hose up to mine today and ran it in the drive. It ran fine and wasn't missing or stalling out. I did pull the plugs and find some build up on them though. I'll take it to the lake tomorrow and see what it does. If I still have problems Ill take it to the shop tomorrow afternoon.

[JUST-IN-TIME]

well in neutral it carbons 2 and 3

in gear u r OK

[Blaine0311]

Well, this morning I ran it just fine for over an hour. I ran it in all RPM ranges. Then just when I went to the ramp to load it up it started acting up again.

Same thing, if I shift from neutral into forward and slowly accelerate it won't get over 1600 rpms. If I shift into gear and gun it, it runs just fine.

When I got back to the house I checked spark plugs. All looked good but I did notice some rust inside spark plug wire connector.

Next step is cleaning out VST.

[brad*84]

You may want to check what is called the fuel canister, it's the last filter before it goes into the injectors on your motor. it's between your fuel tank on your motor and the injectors.

[Blaine0311]

ok, ill check that. i took it out again and narrowed the problem down further.

about half the time it runs just fine, idles normally and throttles up normally. the other half i have this problem.

it will idle very rough with lower rpms than normal idle. its a bouncing idle, as if it were missing. if i leave it idling and put it back and forth from in gear to neutral two or three times, it will start idling normally again and i can take off. if i give it gas in gear when the rough idle problem is there it only gets up to about 1600 rpms. if i give it gas in neutral while the idling problem is there it will either die or slowly rev up to about 2k rpms and then burst through to 4000-5000 rpms.

[JUST-IN-TIME]

that is the return line, but i have seen it go bad

[Blaine0311]

what do you mean "return line"?


i called yamaha, they said that my outboard is one of those that needed the oil pump changed and it hasnt had it yet. maybe the oil pump is running too lean/rich randomly? im going to take it in and have them change the oil pump and do a compression check.

[JUST-IN-TIME]

oops sorry
wrong thread

yes that filter feeds the pump
u need a pressure gauge and a lap top to test the pumps

[Blaine0311]

more question

im going to take it in and have the oil pump changed and a compression check done. since i bought this boat used from a dealer that got it at a repo auction, i have no information on its service history. i'd like to just get any major maintenance done to it now so that i don't run any risks. i'm planning to get the sparkplugs, sparkplug wires, have a 10 micron fuel filter installed and all fuel filters changed. what else should i have done?

i'd also like to get the impeller in the water pump replaced, but someone told me to just have the entire water pump changed instead of just the impeller. he said it isn't that much more expensive and that its better than just changing the impeller.

also, im having a little trouble with my water pressure gauge. sometimes it works, sometimes it doesn't. next time i take it out im going to check the line for obstructions or kinks. what should the line from the outboard to the back of the gauge have in it? water or air? is there anything else i should look for?

so i guess i could sum it up with three questions.

1 - what maintenance should i have done on a 5 year old hpdi with no history?

2 - go for a new impeller or just replace the entire water pump?

3 - should the water pressure gauges hose have water or air in it?