Moomba Mobius LSV 2005 year model

[Garrett Pye]

I am having problems with possibly fuel delivery. its 350 indmar engine. Need help...It cranks up fine, but when placed in drive to go forward the boat chokes down and then shuts off....almost like it aint getting gas. But, it will crank back up then shut back off when put in drive and give gas. Is it fuel filter? Pump? Need help and where would I find these parts?

[mmandley]

Can you rev the engine from the throttle at the divers helm? Should be able to push the bolt in on the bottom of the throttle lever and rev up the engine.
Does the boat also dy when put into reverse?
Can you idle at no wake speed or is it dying as soon as you put it into gear?

As for the fuel filter the easiest way to find it is to follow the fuel line form the fuel rail, or carb if its carbed. You might have a really clogged filter and its just not allowing pressure threw it. Also might be the fuel pump is not allowing enough pressure.
I would start at replacing the filter and then trying the boat again because of the fuel pump is bad then you have to replace the filter anyway.

When the engine is idleing does it sound normal? Smooth and even sounding or does it sputter or anything?

[08LSV]

If not the fuel filter as mmandley said which is probably the easiest/cheapest thing to change, you could try the throttle position sensor if it has one, not sure about 2005's. I had a giant do-do brown '84 Cadillac sedan deville back in the day that did the same thing every time you put it in gear (forward or reverse) and it was the TPS...

[Garrett Pye]

Its carbeurated.
I hope I want sound too confusing, but when I first crank it it revs up and idles great, but after about 3-4 sec I put in forward to take off it will start choking down and then will not idle. Yes, it will do this in reverse as well. Ill def replace filter, if that dont work, then I will go to pump or TPS if it has one. If anything else I need to know, please feel free. Again thanks

[08LSV]

Its carbeurated.
I hope I want sound too confusing, but when I first crank it it revs up and idles great, but after about 3-4 sec I put in forward to take off it will start choking down and then will not idle. Yes, it will do this in reverse as well. Ill def replace filter, if that dont work, then I will go to pump or TPS if it has one. If anything else I need to know, please feel free. Again thanks

I am thinking it sounds more like a fuel issue when its under load. Most engines can idle with very little fuel consumption. Since it happens when you engage the tranny (put it under load) it just doesn't get enough fuel pressure to maintain that consumption. I would try the fuel filter first as Mike said, it will be the easiest and cheapest thing to try. If no luck there you can get/borrow a set of manifold gauges and check the fuel pressure at idle (you can just do a search for indmar carburated engine fuel pressure specs). and then see if it is low or drops before the engine dies when you put it in gear. Next would be the fuel pump if the pressure is low/not adequate. Last it could be anywhere in you carb... Clogged jet/nozzle bad power valve, float etc. not sure what kind of carb you have. Be sure to check your ignition timing and distributor shaft for tightness at idle before the other more labor some tests. Good luck. Hope you get it going soon.

[Garrett Pye]

thank you for you guys help. I just ordered filter. I will try that first, then move on to the pump if it is not working at that point.

[Mikes]

Before you start changing parts,make sure you dont have something wraped up in the prop or shaft. Yes it happened to me.

[Garrett Pye]

alright guys.....fixed the problem,and figured I would relay the message considering you guys have tried to help me just in case it ever happens to you one day...

My boat would crank up,rev up,etc...just fine, but after a few minutes of doing so it would shut off,then crank back up. Well, you know the story, but what i had to do was disconnect my fuel pressure sensor that is located just under distributer and is bolted to the block. Basically, it is a relay switch controlling the electric fuel pump. I simply disconnected the wires hooked to it and connected them together sort of bypassing the switch. Well, the boat ran perfect. Turns out it was the pressure sensor. I quick way to make sure you dont have fuel pump problems is to bypass this switch and you can hear fuel pump running.......if you dont hear it running, then obviously your pump is bad.

hope it helps and makes sence

Garrett

[KSmith]

Is that a fuel pressure sensor? I thought it was a oil pressure sensor.

[08LSV]

Nice Job. Glad you got it fixed!

[Garrett Pye]

no, it was fuel pressure sensor.....I dont know why fuel pumps are electric now, but they are. You never had problems with the old mechanical ones.

[mmandley]

no, it was fuel pressure sensor.....I dont know why fuel pumps are electric now, but they are. You never had problems with the old mechanical ones.

Had to goto Electric when we went to fuel injection due to higher fuel pressure needs and a more steady pressure all the time.

[08LSV]

Yeah the biggest problem with the mechanical ones were that they didn't pump unless the engine was running or at least turning over (Cranking) and it would take too long to build enough pressure for the injectors to work properly. If you notice on most cars now a days as soon as you turn they key to the on position, even before you start you can here the pump running to pressurize the system. I do miss the power of carbs but my wallet like injectors better...