96 Mastercraft Prostar 190, poor fuel delivery

[Evinrude Boater]

Boat starts and idles out fine but stumbles when trying to accelerate. You can see the cone shape of the fuel injecting in the throttle body weakens and changes shape as the throttle is opened. The cone gets smaller as you open the throttle. It's had two new fuel filters. The fuel pressure hasn't been measured. Other than that is there anything else that can be checked to disagnose the problem? Should I open the throttle body to check for debris?

 

[GA_Boater]

What motor is in that Mastercraft?

Do check the fuel pressure. Looking at the spray may not mean much because the increased air as speed increases tends to flatten the cone.

 

[Evinrude Boater]

It's an Indmar 5.7

 

[Bondo]

Should I open the throttle body to check for debris?

Ayuh,.... I'd start the diagnosis at the other end,....

The tank's vent, the dip-tube, the anti-siphon valve, the fuel pump, then the injector,...

 

[Evinrude Boater]

I wasn't able to troubleshoot as Bondo had suggested but I took it on the water and advanced the throttle ever so slowly until it stumbled. Holding at that position I sprayed some fuel in the throttle body and it didn't rev up or run smoother. Make me think fuel delivery may not be the problem.

 

[cup of Joe]

I had that poor fuel delivery problem in the past , It was the anti-siphon valve stuck all most close.

 

[QBhoy]

Check the pick up on the tank...after filter obv. Then the fine strainer on the main inlet to carb. After that and ruling out bad fuel if no better....carb will need a going over.

 

[Bondo]

I wasn't able to troubleshoot as Bondo had suggested but I took it on the water and advanced the throttle ever so slowly until it stumbled. Holding at that position I sprayed some fuel in the throttle body and it didn't rev up or run smoother. Make me think fuel delivery may not be the problem.

Ayuh,.... Then look at the distributor cap, 'n rotor,.....

'n be careful,..... If it is a lean condition, yer settin' up the perfect detonation scenario, which leads to holes in pistons,...

carb will need a going over.

Except it's Efi,....
Still could be crud in the system though,....

 

[QBhoy]

Ah. Assumed it was a carb engine at that age. Fair play.