90 Fourstroke EFI cutting out. idling fine.

[WvRiverMusky]

2006 Mercury fourstroke efi. (1B355828). Motor is idling fine. I do a lot of 4mph trolling with it. went to run back to ramp and after getting planed out it starts cutting out. it rarely quits but shuts down then right when you think its gonna die its fires back up and runs. kinda on off on off sputtering kinda. Checked all I know to check. filter, fuel separator, fuel lines with no noticeable problem. checked plugs and wires. looked good to me. went back out on lake, she idles fine. planed out fine went about 1/4 mile and right back to shutting down and back on and shutting down and back on. done this till I couldn't take it anymore and idle back into ramp no problem. motor starts fine.

One questionable thing I seen was fuel pump pressure. not sure how much fuel it should pump. its pumping but not hard to block off with your thumb. don't seem to be much pressure at all.

Im thinking fuel problem? but what. just top end won't run. low end runs fine.
Maybe plugs?
Maybe fuel pump?

couldn't of went out at a worse time. fought for vacation this week and got it to fish and boats down.
any help would be appreciated. thanks

[Fredfx21]

Friend of mines boat did the exact same thing, two weeks ago. His is a 2011, 115 4 stroke. Above 3000 as the boat planed out, motor, sputtered,laid down and would shut off. He took it to the dealer turned out to be just the fuel filters. No issues since and runs like a scalded dog.

[kyboy192]

Have you replaced the fuel lines? My 2006 fuel line inside liner broke down, it can cause a world of hurt. My was doing the same thing found bad fuel lines. How ever they was just starting to get bad and that was not my problem but a good place to start. Then i did the vst filter it was clean. My problem would come and go. I think it was simply a bad ground. Explained what was was going in to local dealer, he said bad ground, they got to be perfect on efi motors. I just knew I was wasting my time but peeled back some insulation on the battery side, there was some corrosion, cut off about 1.5 inches and put new terminals on. Also removed and sanded were it attaches to motor. I could not believe it actually been fixed been tested 5 times now all is good. If my luck holds out this winter I will replace battery cables with a size bigger and order them custom made.

[WvRiverMusky]

thanks a lot, gonna tear into it asap. all lines I've checked looked good as new to me. ill check ground. local old school boat mechanic is telling me its probably coil. told me to order one and see but I'm having trouble finding parts. anyone know of good online parts source with low prices! learning a lot about these motors and planning on doing some much needed maintenance on it. Filters, oil change, new hub, clean, adjust lines or put new ones on it. I've never touched it and just run it. thanks again.

[EuropeanAM]

See Rhonda's post, sticky at the top of the forum.