Malibu diagnosis?

(angelo_ski) · (angelo_ski) **Join Date: Nov 2006** 07-29-2010, 10:51 AM

I guess it could be an boat, but I have the Monsoon motor. Houseboating recently, I was finding that it would not start in the cool of the morning. It would turn over, but was clearly getting no fuel. Once the sun was up and warming, it started no problem. Second symptom (related?) when at speed pulling, I would lose power. Fuel output would not meet the demand. This was an intermittend issue, sometimes I was fine, sometimes it would sputter with the lightest load. Any ideas where to start?

(texastbird) · (texastbird) **Join Date: May 2003** 07-29-2010, 11:17 AM

How have you observed fuel not making it to combustion or not meeting demand under load? How old is this motor? When was it last tuned up?

(alans) · (alans) **Join Date: Aug 2005** 07-29-2010, 11:19 AM

Low pressure fuel pump is shorting out or dying.

(my_malibu) · (my_malibu) **Join Date: Feb 2008** 07-29-2010, 11:35 AM

fuel filter

(trace) · (trace) **Join Date: Feb 2002** 07-29-2010, 1:29 PM

Second symptom sounds like fuel delivery issues. Not sure on the first symptom.

Go to the auto parts house and get a fuel filter and EFI fuel pressure gauge. Replace the fuel filter, screw the gauge into the schrader on the fuel rail, and leave it there. Check the fuel pressure when you're having problems, should be around 40 psi. If it's low, check the intake screen in the tank for blockage. If that's not blocked, replace the fuel pump. If the fuel pressure is good, I would be looking at the ignition next.

(maxx_wake) · (maxx_wake) **Join Date: Sep 2003** 07-29-2010, 2:04 PM

I am not familiar with the Monsoon but on my motor the low pressure fuel pump actually sits inside of the fuel filter which then sits in a large canister. I had similar symtoms a while back and it turned out that there is a little piece of fuel hose that the pump hangs from inside of the canister and that had a crack in it. It wasnt leaking anywhere because the fuel just went back into the canister but the pump couldnt get enough fuel to the motor to keep it running. It started with symtoms like yours and eventually got to where it would barely run.

(angelo_ski) · (angelo_ski) **Join Date: Nov 2006** 07-29-2010, 3:44 PM

I just had it tuned at the begining of the season, standard service. It may not have included the fuel filter replacement, I will have to check that. Just a note on the start-up issue, I am not hearing the sound that is made when the key is put in the on position, just before starting, thus EFI is not priming/pressurizing before I start it, so it turns over but no ignition. Someone also mentioned to me a microchip in the throttle that signals the EFI system to prime/pressure before starting? Boat is a 2005.