HELP I WANNA BLOW MY BOAT UP!!!!

Hammer11791

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Jul 8, 2017
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i have a 2003 Crownline with a 5.7 Volvo Penta GXI. ive had this problem for 3 years. it will chug between 2k and 4k RPM's, the first 2 years i could put seafoam in and the problem would go away. it ran fine at low RPM's up to 2k and if it was ran over 4k. now we put 4 cans of seafoam in, ran it for about an hour at 4k RPM's then idled for about 30 min. when i went to take off it would stall out. ive put in new plugs and plug wires, new roter cap, cleaned fuel pumps, still dies when i give it gas.
 

ondarvr

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It just sounds like it needs a good cleaning of the fuel system.
 

tpenfield

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Loose the SeaFoam . . . is this a throttle body injector engine or a multiport? Try a heavy dose of fuel injector cleaner. Also check your fuel pressure. Timing checked? Got any codes from the ECM?
 

kenny nunez

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To narrow the problem get a 6 gallon out board tank and set it up where you can connect it to the fuel pump. First run the boat until it acts up, disconnect the fuel line from the tank and put a plug in it to seal it off the hose, then switch to the out board tank and see if there is any improvement. This will show if the problem is with the boat's tank or an engine fuel problem.
 

Hammer11791

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I believe its multi port injection. I put a new fuel line from the tank to fuel filter on and a new fuel filter in. I tried to take the boat out today for a test run but i couldn't get it to even go over 1k rpm's before it would die. its getting worse.
 

tpenfield

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Diagnosing fuel injected engine usually requires at least a code reader, but more likely the full computer program to see what the sensors are 'saying' while the engine is running. All that replacing stuff that you have done, you know that is not where the problem lies.

Do you have the full model number of the engine?
 

Scott Danforth

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start by cleaning your tank and replacing your filters

what is your fuel pressure?
 

Hammer11791

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It does not have a water separator just a fuel filter that i just replaced yesterday. The reason i changed the rotor cap was it had corrosion inside it so i just put new plugs and wire on it because it is easy and cheap. I took it to a shop last week he thought it was fuel pressure regulator so he changed it. he also said the pressure was 29. I thought carb eng was to be 30 and fuel injected was to be higher like 45. Is that correct? I just filled the 60 gallon tank up with non ethanol gas so i don't have anyway to clean it. I was going to try and find a little fishing boat tank and try that. I'll try to get engine number today.
 

alldodge

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said the pressure was 29. I thought carb eng was to be 30 and fuel injected was to be higher like 45. .

Stop the seafoam

Carb motor is 3-7 psi, most GXI's fuel pressure is around 60 psi. The canister filter (the oil filter type) is a water separator and fuel filter.
 

tpenfield

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Interesting.. Does it have a maf?
At any rate, I would be spec'ing any sensors..

Has a MAP most likely. But I agree, it is probably one of the sensors that is acting up and without the computer diagnostics, it is like throwing darts in the dark.
 

Hammer11791

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The shop i took it to said their were no codes on it. Since I turn my batteries off do the codes stay or do they clear every time I turn the batteries off?
He said its a very simple computer.
 

RCSConstruction

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Interesting.. Does it have a maf?
At any rate, I would be spec'ing any sensors..


What is a maf ?
Mass Air Flow sensor.

Tpenfield says it has a Map. (Manifold absolute pressure) Check it with a meter. Plenty of how-to's on internet. Just use a chevy truck map sensor test procedure.
A vacuum leak would cause issues too since this sensor trims fuel based on engine load and vacuum.
 

tpenfield

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Try disconnecting the tachometer . . . sometime they can raise havoc with the ignition if/when they start to fail.
 

alldodge

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Turning bats off does not clear codes, and as others mentioned you do not have a MAF, you do have a MAP.
 
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