PLEASE help! 88 evinrude 40hp

[engine391]

Ok, here is what I know or have done to the motor thus far:

Has good spark from both coils
Compression is good on both cylinders
Cleaned and rebuilt carbs
new fuel lines
still has VRO pump - oil disconnected and line plugged
replaced fuel primer solenoid (was blowing fuses)

The motor is running really rough, no power unless I hold in on the choke. It will run fine on muffs, idle all day long. As soon as I put it in the water, it dies, wont idle, and runs like crap. Would like to have some advice on what I should look for. I am lost!!!!

 

[Daviet]

Re: PLEASE help! 88 evinrude 40hp

If you have to use the choke to make it run it sounds like a fuel problem.
What are the compression readings?
The only difference between running on muffs and in the water is the back pressure in the exhaust system. What idle speed is it running at in the water, and on the muffs? If the idle is to low it cannot over come the exhaust back pressure when idleing in the water, and will stall.

 

[engine391]

Re: PLEASE help! 88 evinrude 40hp

The only other thing I can think that is wrong is the fuel pump on the VRO is half working. What should the fuel pressure check if I hook a gauge up to the pump?

Also, if i remove the VRO pump, which fuel pump should I get for it?

 

[engine391]

Re: PLEASE help! 88 evinrude 40hp

Compression is 130 and 127

 

[Daviet]

Re: PLEASE help! 88 evinrude 40hp

Compression sounds good, But if you have to use the choke to keep it running you have a fuel delivery problem. If you pump the primer bulb and it helps the problem, you might have a fuel pump problem. if it doesn't help, you might have to overhaul the carb.
Try using an inductive timing light to check spark while is running and make sure that you have spark on both cylinders while the engine is running.
As stated in prior post, what is the idle set at? If idle is to low it will not run in the water.