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View Full Version : NEED HELP 2000 Moomba Mobius V Indmar Asalt MPI bogging down



Pchrzanowski
07-05-2015, 02:32 PM
Need help. Have been reading all of the Need help. Have been reading all of the forms. Change plugs, distributor cap, rotor, ignition module, oil, fuel filter, low-pressure fuel pump, Coil. Starts on first try, idols perfect. Out of the whole strong 3000 RPM runs great, for about 10 minutes. Then bogs down does not stall, continues to idle just fine. Shut off engine, let's set for 1 to 2 minutes then restart everything is OK for another 5 to 10 minutes 3000 RPM run strong and then bogs down does the same thing repeats.
I'm thinking it may be the TPS? Or the high-pressure fuel pump? Also saw a post for the pick up line in the tank. Also removed both fuel lines from top of tank and there are no anti-siphon devices. I'm thinking it may be the TPS? Or the high-pressure fuel pump? Also saw a post for the pick up line in the tank. Also removed both fuel lines from top of tank and there are no anti-Siphon valves. I'm thinking it's electrical. Oil pressure gauge at 3000 RPM is reading between 50 and 60. I read on another forum, that if the oil pressure sending unit is going this can i'm thinking it's electrical. Oil pressure gauge at 3000 RPM is reading between 50 and 60. I read on another forum, that if the oil pressure sending unit is going this can cause the engine to go into limp mode? Any help would be greatly appreciated as I've reached a point where I'm not sure what else to try. This is happening with a full tank of gas all the way to one quarter tank of gas so I'm not sure it's the pick up line. I'm thinking it's electrical, any other thoughts?forms. Change plugs, distributor cap, rotor, ignition module, oil, fuel filter, low-pressure fuel pump, Coil. Starts on first try, idols perfect. Out of the whole strong 3000 RPM runs great, for about 10 minutes. Then bogs down does not stall, continues to idle just fine. Shut off engine, let's set for 1 to 2 minutes then restart everything is OK for another 5 to 10 minutes 3000 RPM run strong and then bogs down does the same thing repeats.
I'm thinking it may be the TPS? Or the high-pressure fuel pump? Also saw a post for the pick up line in the tank. Also removed both fuel lines from top of tank and there are no anti-siphon devices. I'm thinking it may be the TPS? Or the high-pressure fuel pump? Also saw a post for the pick up line in the tank. Also removed both fuel lines from top of tank and there are no anti-Siphon valves. I'm thinking it's electrical. Oil pressure gauge at 3000 RPM is reading between 50 and 60. I read on another forum, that if the oil pressure sending unit is going this can i'm thinking it's electrical. Oil pressure gauge at 3000 RPM is reading between 50 and 60. I read on another forum, that if the oil pressure sending unit is going this can cause the engine to go into limp mode? Any help would be greatly appreciated as I've reached a point where I'm not sure what else to try. This is happening with a full tank of gas all the way to one quarter tank of gas so I'm not sure it's the pick up line. I'm thinking it's electrical, any other thoughts?

bergermaister
07-06-2015, 01:26 AM
Maybe try reaching out to Engine Nut here via PM. Lots of questions, unfortunately not a lot of answers.

zabooda
07-06-2015, 11:24 AM
The fuel pump is a good possibility. The pump should be changed if it is the original.

Pchrzanowski
07-06-2015, 12:58 PM
Don't know if it's the original. I've only had the boat 4 seasons. Haven't had any issues till now has run strong. I don't know if it's the fuel pump. I replaced the less expensive low pressure pump, but the high pressure pump on top of the filter housing is going to set me back another $300+ so I was hoping someone might have had the same issue and saw something I haven't thought of yet.

jzelt
07-06-2015, 04:35 PM
Our TPS symptoms were it would go if you went steady pressure on the throttle, but hammer it from a stop and it would bog. Get off the throttle would continue a rev around 3K RPM until I did a quick bump of the throttle and it would idle down. Like you, shut it off and it would return to idle fine. It also started belching out black exhaust more frequent. Replaced it and no issue since.

Pchrzanowski
07-13-2015, 01:09 PM
Thanks for replying.heading to lake this weekend. Going to try the TPS

Pchrzanowski
07-20-2015, 11:49 AM
Need help. 2000 Moomba Mobius V. Have been reading all of the forums on Moombas with 350 Indmar MPI losing power at 3000 rpm and going into limp or rpm reduction mode.

Started out small and cheap but now maybe not so much with the list of parts growing unnecessarily. Good learning experience on all of these components and how to change them yourself, but killing the wallet! Not to mention, Dad is losing serious credibility with, "OK boys, I think this is it, no really, this time we'll be in business." Mama just rolling her eyes and telling me to drop it off at the dealer $$$$$$$$$$$.

Symptoms: engine starts on first crank hot or cold. Idles perfect. Strong out of the hole 3000+RPM. With no load everyone in boat, runs 15-20 minutes. Then drops RPM down to limp mode. Doesn't stall just white smoke and bogging down. Shut it off and let sit for 1 minute or less then restart everything is OK for another 5 to 10 minutes 3000+ RPM even pulling 2 tubes or a wakeboard runs strong and then bogs down under load. Makes for an interesting hour in the water testing new components installed with the crew and a lot of sad faces.

So here we go, this season, changed plugs, changed gap from .035 to .060 (plugs came .035 new, book says .060) new distributor cap & rotor (needed it anyway), new ignition control module while cap was off (why not it was still early in the game) new fuel filter (wow was this a chore, under a vacuum or King King put the last one on, took 3 hours and a lot of skin), next new low-pressure fuel pump (screen was clean as a whistle) new Coil, TPS, idle control valve, checked for anti siphoning valves in fuel lines there were none at the tank? Lines do not appear to be kinked or collapsed or breaking down i only run 100% gas no ethanol in every tank. Changed the anti knock sensor most recently and haven't tried a run yet due to weather came in this past weekend.

This is happening with a full tank of gas all the way to one quarter tank of gas so I don't think it's the pick up line. I'm thinking it's electrical. Like fuel pressure regulator? Perfect pass malfunction? I've been running the PP off since last year. If we hit a big wake the PP would kick in and rev the engine down.
It may be the high-pressure fuel pump but at nearly $300 I'm hesitant to add another part as lots of the folks on the forums did this and got no result.
I recently saw a post regarding Perfect Pass issues. How do you disconnect the Perfect Pass electrical inputs in order to override? I'm thinking it's electrical causing it to go into RPM reduction/limp mode.

Another thought is the Oil pressure sending unit. The gauge at 3000 RPM is reading between 50 and 60. I read on another forum, that if the oil pressure sending unit is going this can cause the engine to go into limp mode.

I'm committed to chasing this down. The forums all make it clear, a trip to the mechanic may yield a new ECU or a new HP fuel pump only to be out another $1200-$1500 while having the same issue. So I'm not inclined to go that route until I've exhausted all of my options as a backyard mechanic.
Thanks in advance.

jzelt
07-22-2015, 09:55 AM
Doesn't stall just white smoke and bogging down.

Our TPS was putting out black smoke meaning it was running too rich and dumping fuel.
You mention white smoke. That I believe is steam. Now it could just be exhaust water, but if it is more than usual, then I would lean toward water in the cylinders. Possible gasket for riser, etc.

For cars, but explains the exhaust color fairly well and what to diagnose it as.
http://www.trustmymechanic.com/car-smoking-from-exhaust-pipe/

BT_48170
07-23-2015, 08:19 AM
Might be worth checking your fuel pressure kill switch too (this is different than the oil pressure sender), doesn't really sound like that is the problem but when mine went it acted pretty strange, first would just bog, then when it really went bad it would just die. Not sure on a 2000 but for 2005 this kill switch was back by the distributor. You can just jump the wires together to see if makes a difference, wont cost you anything to check it off the list.

sailnaked6842
07-23-2015, 09:00 AM
If what I know about cars transfers over (and I think generally it does) you're probably losing communication from a critical component to the engine, such as a sensor. Because of this the engine is dumping TONS of extra fuel into the motor to prevent critical damage making it smoke and bog. Unfortunately you'll need to go to the dealer to see if it's throwing a code because a marine code reader is more of a luxury item than a cell phone app. Do any of your gauges do anything funny? You may want to check wires and connections for your temperature and oil pressure. Maybe crank position sensor? Not sure if they had them back then, but it fits the bill for it.