89 Volvo Penta AQ271C ignition or carb, maybe something else

[Scott Danforth]

did you get fuel pressure?

 

[Dillon36]

did you get fuel pressure?

Not yet, work keeps getting in the way.
I need to get a pressure gauge

 

[Dillon36]

Heading to the boat, what should the pressure be?

 

[Scott Danforth]

Heading to the boat, what should the pressure be?

4-7psi at the carb

also check the opaque yellow line from the fuel pump vent to the spark arrestor to make sure there is no fuel in that line. if there is, your fuel pump has failed.

 

[Dillon36]

4-7psi at the carb

also check the opaque yellow line from the fuel pump vent to the spark arrestor to make sure there is no fuel in that line. if there is, your fuel pump has failed.

5.5psi

 

[Dillon36]

5.5psi

No fuel in line

 

[Scott Danforth]

Fuel pressure is good

Try running the engine from a small portable tank with known good fuel?

 

[Dillon36]

Done that already…

I’ve about done all I know to do.

 

[Scott Danforth]

Did you replace the cap and rotor? I did not see anything in the thread.

 

[Dillon36]

yes sir, on of the first things i went after along with wires

 

[Dillon36]

yes sir, on of the first things i went after along with wires

here is a list

Cap, rotor, wires, plug, coil
Doubled checked firing order
set timing many times to be 100%
Distributer tested good, replaced dizzy
Fuel pump good
Carb rebuilt twice, new power valve, tuned by carb mechanic
Tried new carb
removed rev limiter
small fuel tank with new gas
Cleaned outdrive and props
trying to remember what else...

all with no change at all

 

[Dillon36]

good morning,

anything else you can think of? I'm stumped

 

[Scott Danforth]

good morning,

anything else you can think of? I'm stumped

your compression is good
your fuel pressure is good
you stated you changed cap and rotor and validated that the ignition advance is correct

you also tried a different carb

maybe have a talk to the carb guy. did he set it up factory?

the 715 CFM carb on the 271's has a #25 power valve (I ran a #45), #72 primaryjets and the secondary jets are staggered at 80 on one side and 90 on the other (as set up factory by Holley for Volvo). it does have a pink spring in the vac diaphragm chamber. I tried others and went back.

After I added a cam and vortec heads to the motor, i ran #74 primary and #88 secondary.

when I changed motors to the 468, I ran #75 primary, #88 secondary and changed the accelerator pump squirter from a #26 to a #28

Back to your motor. Have you tried different props?

 

[Dillon36]

I know the carb dude tried rejetting but I'm not sure the size but it made to differance. I have the same props due to the fact that it ran perfect until it didn't. All this just makes no sense to me

 

[Scott Danforth]

Check to make sure the motor is at TDC when the damper ring is at TDC. Will require a piston stop. Your damper ring could have moved ( it is 34 years old)

Make sure the jetting is correct per spec

 

[Dillon36]

OK,

I'm away for a few days but will get back at in a few. Thanks

 

[Scott Danforth]

Pull the rubber exhaust hoses. If you had an overheat, the inside of the rubber could have burnt plugging the exhaust on one side limiting power

 

[Dillon36]

so had a good talk with a buddy of mine and today he changed the water/fuel separator, added a spacing plate between the carb and readjusted the carb. He had told that he had already changed the filter but apparently not. That's the first thing I would have checked.

Anyway, the boat to 3400 rpm which is an improvement but still not perfect. My guess now is that there is water in the tank. Going to drain the filter again in a day or so to check for water. So frustrating.

 

[Scott Danforth]

Don't just drain the filter. Change it. And remove the sending unit and siphon the water out

This is progress

 

[Dillon36]

Don't just drain the filter. Change it. And remove the sending unit and siphon the water out

This is progress

Yep, thats this weekends project.