Need help, 1997 Malibu 320hp EFI, sputtering at higher RPMs

[97echelon]

Just purchased a 1997 Malibu echelon with the 320hp monsoon and on test run boat ran great at all rpm ranges. The boat sat with about 5 or 10 gallons of gas in it for a few months. Filled the boat up and hit the lake. Took the kids out wake boarding and ran great for the first hour. Then it started sputtering and would shut down. Boat would start back up and run fine. I put some gas treatment in her and she ran good until the next day. Then at higher RPMs would spit and shutter and cut off. Boat would crank back up then run fine until I got to higher RPMs again. I'm stumped has anyone had this type problem before? Any help would be great. Thanks so much.

[97echelon]

By the way boat runs at 180 degrees any thoughts into this. To high or normal. Previous owner reports Boat has always ran at that temp since new.

[MALI-MONSTER]

Well, I know very little about engines, but I too just bought a 1997 Echelon with a 320 Monsoon. I can tell you that the thermostat on my boat keeps it running at a steady 140 F. I don't think that is your issue though. I assume that you have done all the simple stuff like changed the spark plugs, cleaned the flame arrestor, and changed the fuel filters? I believe that there are two fuel filters one that sits on top of the gas tank and another on the engine. If the engine is failing it is either not getting spark, air or gas. I bet that it is gas in your case. I would start with the fuel filters then consider the fuel pump. Where are you located?

[lonster]

Just purchased a 1997 Malibu echelon with the 320hp monsoon and on test run boat ran great at all rpm ranges. The boat sat with about 5 or 10 gallons of gas in it for a few months. Filled the boat up and hit the lake. Took the kids out wake boarding and ran great for the first hour. Then it started sputtering and would shut down. Boat would start back up and run fine. I put some gas treatment in her and she ran good until the next day. Then at higher RPMs would spit and shutter and cut off. Boat would crank back up then run fine until I got to higher RPMs again. I'm stumped has anyone had this type problem before? Any help would be great. Thanks so much.

Have had issue with 320 monsoon in 1996 response..fuel pump filter screen was plugges..I replaced filter (only one) by the fuel rail and still had the problem. If you take the fuel pump off and turm it over there is a screen in the bottom..mine had debris in it. I could tell the problem was starting again when I could hear the fuel pump at idle. Many people will reply and say there is a fuel filter at the tank but my boat intially only had one.

Lon

[skiguy]

It's a process of elimination. I'm guessing it's fuel related based on the description. Definitely change the fuel filter at the fuel pump and the one at the tank (the most important one) if it has one. If that doesn't work you may want to plug a fuel pressure gauge onto the Schrader valve just after the fuel pump, run it under load in different rpm ranges and see how your fuel pump is performing. On my 98 Sunsetter with the 325 Monsoon it should hold 40 psi. As mentioned above there is a small screen within the inlet fitting on the fuel pump however I have to warn you if your engine is anything like mine good luck getting that sucker off. I took a stab at it a while back when having a hesitation issue and the location of the pump (even with the floor) made it practically impossible to get a wrench on that fitting -- it would have meant taking the whole pump off the engine.

You could also try draining the fuel tank and running fresh gas just to eliminate that as a variable.

Good luck!

[lonster]

It's a process of elimination. I'm guessing it's fuel related based on the description. Definitely change the fuel filter at the fuel pump and the one at the tank (the most important one) if it has one. If that doesn't work you may want to plug a fuel pressure gauge onto the Schrader valve just after the fuel pump, run it under load in different rpm ranges and see how your fuel pump is performing. On my 98 Sunsetter with the 325 Monsoon it should hold 40 psi. As mentioned above there is a small screen within the inlet fitting on the fuel pump however I have to warn you if your engine is anything like mine good luck getting that sucker off. I took a stab at it a while back when having a hesitation issue and the location of the pump (even with the floor) made it practically impossible to get a wrench on that fitting -- it would have meant taking the whole pump off the engine.

You could also try draining the fuel tank and running fresh gas just to eliminate that as a variable.

Good luck!

In the Response/Echelon it is easy to get to..1/2 hour tops..and yes i take the pump off the engine..the more i think about it you will need to remove a fitting adapter on the bottom of the pump to see the screen..

[97echelon]

Well, I know very little about engines, but I too just bought a 1997 Echelon with a 320 Monsoon. I can tell you that the thermostat on my boat keeps it running at a steady 140 F. I don't think that is your issue though. I assume that you have done all the simple stuff like changed the spark plugs, cleaned the flame arrestor, and changed the fuel filters? I believe that there are two fuel filters one that sits on top of the gas tank and another on the engine. If the engine is failing it is either not getting spark, air or gas. I bet that it is gas in your case. I would start with the fuel filters then consider the fuel pump. Where are you located?

[97echelon]

Thanks guys for the reply, yesterday I replaced the fuel filter on the engine and checked the plugs. I did have some pine needles stuck in the transmission cooler heat exchanger and cleaned that out. Took it to lake today did some wake boarding and after awhile it started the same sputter and cutting out. Turned motor off then back on and it would run fine.. I hammered down on it and ran pretty hard for about two to 5 min. And she didn't miss a beat until I backed off down to 30mph. Then it started again. Boat still running at 180 degrees. I'm stumped.

[97echelon]

Took boat to the malibu dealer yesterday and haven't gotten a call back yet. I'll let ya know what they find.

[97echelon]

Well took my boat to the local Malibu dealer. They ran the boat for over an hour and it never missed a beat. They checked the fuel pressure and had good pressure. Now I'm really stumped. I did run some sea foam with this last tank. Going back to lake this weekend to test out some more.