So I went to launch for the first time this season on Thursday. The starboard engine fired up perfectly but the port engine just cranked, won’t fire. I shut the starboard engine down and began checking out the port engine. I noticed right away that the Cool Fuel electric pump wasn’t cycling. I then checked the fuses and relays to find all were good. I checked the voltage going to the electric pump and have full voltage. It appears that the pump has seized.

20+ years of owning/ working on boats with Cool Fuel and I’ve never seen this before. I did some digging and found Mercruiser TSB 2004-01 that indicates that it’s a known issue that the pumps become gummed and lock up. They recommend that you “Leave the pump full of a mixture of fresh gasoline and Fuel System Treatment and Stabilizer overnight” and then try to cycle it.

Has anyone else experienced this before? I have twin 500EFI’s which the Cool Fuel modules are mounted to the bottom of. Based on the space I have to work with, I’m looking at an engine out job to swap the pump - not looking forward to that. I guess this is what I get for storing it with ethanol fuel... I’m going to try Merc’s method but it’s going to be tricky getting the fuel treatment down to that pump. I’ll try through the mechanical pump’s lines.

Any other suggestions or experience with getting one of these pumps to cycle again would be appreciated.

A seized pump should blow the fuse... they draw a lot of amps.

I would try running a jumper wire to the hot side of the fuel pump relay (should be a gray wire), just send 12V to it and see if you hear the pump run.
Also, there is an in line connector for the fuel pump wires, so that could be a place where a poor connection is the problem.

I appreciate the reply. It hasn’t popped the fuse, at least not yet. I disconnected the in-line connector at the fuel pump you referenced and get full voltage when I cycle the key. That connector and wires all seem to be good and clean, no apparent issues.

Hmm. I suppose if there was an open circuit in the pump it might act like that. Broken connection somewhere internal to the pump housing possibly? Doesn't help you with avoiding a lot of work to get to it though.

Confirm that the connector has good ground on the other pin?

Ive never seen a seized cool fuel pump before, as stated I would expect it to blow the fuse. were you reading the 12 volts acrossed the pump terminals or from block to 12 volt hot? Id have to dig around in a harness or wiring diagram but I will say, it may have 12 volts ign on and ecm closes relay to ground it, alot of other things on these work that way, try running jumper wires to it and see if it works and try giving it a couple smacks with something

Good call on checking the ground. Weather permitting, I’ll get out there and check that later. If there’s a broken connection, it would be somewhere between the pump itself and the connector to the harness which is only about a 6” run. The other thing with that is that nothing has changed with the system since October when it was winterized, it’s not like something would have physically disrupted that wire/circuit.

I’m reading the voltage directly at the fuel pump connector on the wiring harness. It’s the two wire lead for the pump that’s integrated into the EFI harness. This is the wire that runs down the left side of the block that the fuel pump clips into it. I’m getting full battery voltage from the harness side of the fuel pump lead when the key is cycled. This harness is powered via the fuel pump relay when energized by the ECU.

I also plan on force feeding the pump with jumpers too. Might as well try reversing polarity on the pump while I’m at it to see if that might free it up.

These things are damned expensive BUT...I wonder if it is one of those 'spares to have on board'?

Interesting point and to that end I ordered a new one yesterday to prevent any further delay if I can’t get this one up and running. I’d say though, this is not something that one could easily field swap on the fly in the event of failure unless there’s plenty of room to work in front of the engine(s).

I have a couple used OE pumps if you need one or two or spares..........