Fuel Delivery Problem on 115 FICHT

[rustyscrew]

This problem has some history so here are some pertinent details and chronology of problem:

Engine: E115FPXEEC

End of June, I got water in the fuel and it got past the water/fuel separator in the engine and stalled.
I drained some and took it into the shop and they cleaned the water from the system and replaced the plugs ($850).
I emptied the 40 gallon fuel tank, removed all water and replaced the sender and checked over the pickup.
When I attached the engine to the boat fuel tank after the service, there was a vacuum in the line and it was hard to get any fuel with the primer bulb
I removed the pickup and pulled the fuel directly from the tank to get the boat to its slip.
I figured the anti-siphon valve was rusted so I pulled it and cleaned it, but upon replacement it didn't fix the problem.
I bought a new anti-siphon valve and primer bulb and gave it to my co-owner to install.
He ran the boat but I don't think he was paying attention to the fuel line at all.
When I got on the boat next, the engine was running terribly. Wanting to stall at low RPM in gear and shuddering on acceleration.
The bulb would get sucked down at idle cruising the harbor. I could keep it running by pressing the bulb.
I went through every part of the fuel system, even trimmed the pickup so it is 1" from the bottom and replaced the antisiphon valve with a regular barb fitting. This solved the vacuum problem, but the engine still runs really badly and will stall at idle unless I pump fuel to it.

It strikes me as a low pressure fuel pump problem. Could this be induced by the bad anti-siphon valve?

The mysteries to me are:
1) why did the primer bulb only suck down at low RPM, but not at high RPM?
2) What are the chances of having 2 bad anti-siphon valves? Was there something else going on?

I apologize for a lengthy post but I tried to include the pertinent info. Basically the fuel system is fine now, but fuel delivery seems to be a problem. Is it a problem that was caused by water in the fuel or by running with a vacuum in the fuel line?

thanks in advance for any advice!

 

[woody66912]

Re: Fuel Delivery Problem on 115 FICHT

I would think that if you have had such high vacuum that the lift pump diagram is failing somehow, as in a pinhole, letting raw fuel into the crankcase . So at idle it's running rich, and at WOT or off idle it's burning that little amount of fuel.

 

[rustyscrew]

Re: Fuel Delivery Problem on 115 FICHT

Thanks Woody. It looks like the assembly is pricey. Do you know if it is possible to purchase just the diaphragm?

 

[rustyscrew]

Re: Fuel Delivery Problem on 115 FICHT

Given that the system had water in it, I am afraid of doing an expensive serial replacement of all fuel system components. Clearly the VST and/or injectors COULD have been damaged by the water, but the mechanic said they checked out. But if I am experiencing stuttering and stalling that is fixed by pumping the primer bulb then that pretty solidly indicates a problem with the lift pump right?

When I pump the primer bulb the engine will change rpm and rev a little, stutter, then return to normal idle. Just another possible clue that could be useful in diagnosis.

thanks

 

[woody66912]

Re: Fuel Delivery Problem on 115 FICHT

You can get just the repair kit, part # 439881. Goto (shopbrp.com) you can buy it there. Really the best way to check this pump is to look inside.

 

[multimech]

Re: Fuel Delivery Problem on 115 FICHT

Put a fuel vacuum gauge on the engine and run it. You should have no more than 4 hg of vacuum at any speed. This will check the entire fuel system to the engine.

Put a pressure pump on each side of the lift pumps pulse lines. Put 15 psi on the diaphragm and see if it holds. If it does the pump is alright.

I concur that the water could have damaged any one or more of the fuel components.

 

[rustyscrew]

Re: Fuel Delivery Problem on 115 FICHT

Thanks woody and multimech. I think I will order the kit and do the tests. If it checks out and the diaphragm looks OK I can always just return it.

Really appreciate your help. I will let you know how it goes.

 

[rustyscrew]

Re: Fuel Delivery Problem on 115 FICHT

Just a quick followup. The mechanic requested to see the boat before I got around to testing the pressures. He found nothing wrong with fuel pressure. He said it is getting too much fuel and oil and it may be associated with a bad computer or bad injector. Funny thing though is that his diagnostics computer doesn't work on my engine. He is at a loss. I am going to start a new thread for ideas on this. Thanks for all the input.