Boat won’t take off

[Apollo0484]

i have a 2007 glastron MX175 with a Volvo Penta 3.0. It’s the red style engine. It starts up and idles fine, but when I take off it takes about 10 - 30 seconds before it starts to really take off. It used to take right off, but now it seems like it’s bogging down. I have it at full throttle, but the RPM’s stay low and it doesn’t go anywhere. After the first slow take off period it appears to clear out and starts running fine. If I stop and start going again when it’s warm it doesn’t do it, but if I stop for a swim and it cools down the same problem starts again. I replaced the fuel filter, and the local marina told me it was a carb problem. $700 dollars after a carb replacement the problem is still there. Thought?

 

[Scott Danforth]

welcome aboard

look at your complete fuel system. if its fuel related, it may also be the anti-siphon valve or issues with the fuel filter

since you had paid $700 to the marina to replace the pump, take it back to them and ask them to fix the problem that wasnt the carb. it could be dirt in your fuel system that is now getting into your new carb.

 

[alldodge]

What is the complete motor model number?

 

[Apollo0484]

I took it back to the marina and they said "it's bad gas." Didn't really get much else out of them. Needless to say I don't know I'll continue going back. The fuel filter was replaced, but I'm not sure about the anti-siphon valve.

The complete model number is 2007 Volvo Penta 3.0 GL.

 

[alldodge]

Being that new its probably a GLM or P
Since it does fine once it warms up, I would look at the choke and see if its hanging. If you stop for a couple hours to swim the choke should not be closing. The choke should be straight up and down.

If its not the choke, then something in the carb and may need a rebuild/cleaning

Don't see bad gas being the issue since it runs fine once warm and running

 

[Apollo0484]

I did have an issue with it starting after the new carb was installed. The marina came down and mentioned it was an issue with the choke, but to be honest I'm not sure what I'm looking for with the choke or where it's at.

 

[alldodge]

Choke plate

 

[Apollo0484]

I plan to run it this weekend so I can take a look then. Just to clarify, should it be open when it's cold or closed? Same question for when it's warm.

 

[alldodge]

It should be closed with a 1/8 inch gap when cold
Should be open when warm

 

[Apollo0484]

Everything with the choke was fine when I ran it this weekend. Closed with small gap at cold, open when warm.

Still just doesn't want to run correctly.

 

[alldodge]

Your saying it still runs fine once warmed up, but not after you stop for a while or when cold?

Pull the fuel filter and dump contents into a clear container to see if anything is there but clean clear gas
Need to check fuel pressure to see if its between 3 to 7 psi
Next do a compression test

If this is good, will need to get into the carb

 

[Apollo0484]

I'll double check the fuel filter tonight. Is there an easy way to check the fuel pressure and compression?

As I'm not an avid mechanic I doubt I'll have the necessary equipment for either, but just curious what your thoughts are.

 

[alldodge]

For fuel presssure you need to place a Tee fitting inline between fuel pump and carb. The Tee can be made by removing the fuel line and replace with rubber and a Tee

https://www.harborfreight.com/fuel-pump-and-vacuum-tester-62637.html

Or get an adapter for inline. Remove line at carb install fitting



For compression test, need a compression test gauge. Should be able to get one from local auto store loaner program. Remove all plugs and mark all plug wires so they can be reinstalled. Have the motor warmed up some prior to pulling plugs.

Disconnect wires from + side of coil. Place throttle in wide open position and install gauge on first cylinder. Crank motor over at least 4 times then record pressure. Can try a couple times by releasing pressure off gauge. Then repeat step for each cylinder. Once recorded, put everything back together

 

[Apollo0484]

Looks like you can get the compression tester at HB too!

https://www.harborfreight.com/compression-test-kit-8-pc-62638.html

The kit you sent the link for looks like it has the T fitting. So, technically I could splice that in and attach to the pressure gauge, correct? I'd just need a new fuel line afterwards.

 

[Apollo0484]

Also, what should the readouts be for the compression test?

 

[alldodge]

I would say at least 120 psi

Don't cut you fuel line, get some adapters from the auto store to make one up. I use to get some short pieces of rubber fuel line and hose clamps and place it on the end of the original fuel line. Then just needs an adapter to connect to the carb.

Might be hard, but try to find an older parts guy, they will be able to advise what will work. Since your not working with much pressure it doesn't take a lot to keep it from leaking

 

[Apollo0484]

I'll give it a go!

BTW, really appreciate your attention and help on this. Thank you very much!

Most people might just say take it somewhere or stop responding. Any who, thanks for the help.