Port engine WOT only gets to 3500 rpms

[charlg]

The boat gets up on plane well, but the port engine maxes out at 3500 rpms. I have to pull the starboard throttle down to match it and that is about 3/4 WOT. The top speed is only 40 compared to 50 last year.

Is there an adjustment that can/needs to be done?

 

[ardeprint]

Sounds like fuel pressure problem or ignition.

Did you repair or replace anything?

 

[charlg]

Sounds like fuel pressure problem or ignition.

Did you repair or replace anything?

At the end of last season, that engine would stall when I tried to push her over 2000 RPMs. I am looking that the repair bill that says they replaced the ignition sensor assembly. At the time, I remember them saying it controlled the fuel flow. I had them replace it on both motors.

 

[ardeprint]

I would test your fuel pressure. It might be the pump or regulator.

 

[charlg]

How would I test these?

 

[charlg]

Any other thoughts on this probem? It takes me about an hour and a half of no wake speed before I am in an area that I can bring her up on plane. I'd like to try to probelm solve at the dock.

Thanks.

 

[Jack380AC]

Have you had the compression checked? I have very similar symptoms and they found my comppression to be bad is several cylinders. That will mean a "top end" repair (or worse).

 

[charlg]

Have you had the compression checked? I have very similar symptoms and they found my comppression to be bad is several cylinders. That will mean a "top end" repair (or worse).

Would there be any other symptoms if the compression was bad? The engines are starting and running very smooth.

 

[Jack380AC]

Would there be any other symptoms if the compression was bad? The engines are starting and running very smooth.

Engine starts fine but sometimes takes a few extra attempts. Seems to run OK at lower RPM but will not keep up with the other engine at higher RPM so subsequently, can not get on plane.

 

[ardeprint]

Compression check is not a bad idea.

To check your fuel pressure is very easy. I am assuming you have MPI.
1- Buy a fuel pressure guage at any auto parts store ($25-$60)
2- Locate a valve on the crossbar on your fuel rail. (looks like a tire valve but bigger)
3- Turn ignition to on and listen to the pump come alive. At this point pressure should read 40PSI or more for 3 seconds then drop 2-3 PSI.
4- If pressure is below 35 PSI, while pump primes, you have a fuel pressure problem. If pressure is 40 or more turn engine on and after proper warm up increase RPM. Pressure should not decrease as RPM increases.
5- If all is well you may want to have a sea trial to make sure pressure stays constant under load.

I would do a compression test as adviced to be sure.

 

[themikehyde]

Had a similar issue. I ran a compassion check and number 4 had 20 lbs and number 5 had nothing. Pulled the heads and found 2 tuliped exhaust valves. Machinist pulled the valves and found all the seats had sunk. He said they were not hardened. He is replacing all the seats and valves. I should get them back tomorrow. Anxious to see how she runs this weekend.

 

[northern]

Had this problem twice. Once it was a coil the second time it was a fuel pump. After replacing the fuel pump it failed after 25 house because of a defect. 100 hours later second one is still working. Coil is cheep and people on this site recommend they be changed from time to time.

 

[charlg]

Compression check is not a bad idea.

To check your fuel pressure is very easy. I am assuming you have MPI.
1- Buy a fuel pressure guage at any auto parts store ($25-$60)
2- Locate a valve on the crossbar on your fuel rail. (looks like a tire valve but bigger)
3- Turn ignition to on and listen to the pump come alive. At this point pressure should read 40PSI or more for 3 seconds then drop 2-3 PSI.
4- If pressure is below 35 PSI, while pump primes, you have a fuel pressure problem. If pressure is 40 or more turn engine on and after proper warm up increase RPM. Pressure should not decrease as RPM increases.
5- If all is well you may want to have a sea trial to make sure pressure stays constant under load.




I would do a compression test as adviced to be sure.

Are these the tools that I should have to perform the tests?
http://www.actron.com/product_detail.php?pid=16170

http://www.actron.com/product_detail.php?pid=16174

They are about $33 each on Amazon.

 

[ardeprint]

Are these the tools that I should have to perform the tests?
They are about $33 each on Amazon.

Yes...