Fuel Restriction...Jet Boat Dies

[ajaquino]

I have Mercury Optimax SportJet 250...I just changed fuel lift pump and added additional fuel/water separator. Last week went out on river and noticed engine kept dying and I had to keep pumping fuel bulb to get the fuel up. Took the additional fuel/water separator out today and went back out. I was able to go about 25miles out to the bay with no issues until coming back when the engine kept dying again and I had to keep pumping fuel bulb. I pumped the bulb numerous times in a series of 4x every 5 minutes until dock. Any suggestions? Fuel bulb? Fuel lift pump? Lines?

Thanks for the help in advance.

 

[tdonoughue]

I would check the fuel lift pump first. Any way to measure the pressure on it against spec?

Fuel filter ok and changed recently?

 

[ajaquino]

Yes changed the fuel lift pump, fuel filter, and original water/fuel separator filter prior to me adding addition separator all the same time because I had bad gas to the start of the season.

 

[Beachbummer]

Generally the fuel/water separators are advertised as high-flow and should not restrict...but it seems to be the recent change for you. Can you confirm no leaks or restrictions that would cause or contribute to this?
Any chance since you had bad gas the separator is already full of water (Unlikely, I know, but cheap and easy to check?)

Best of Luck!

 

[ajaquino]

Yes I ran the bad fuel through the new separator before i changed the filter of the old 1, hence i left new separator in line figuring it wouldnt hurt. Doesnt seem to be any leaks as i was able to go quite far before i noticed fuel problems again and the fuel bulb was not stiff and inflated and i had to pump it in order to get engine started.

 

[tdonoughue]

What happened to the bad gas? I did you drain it all? Or treat it and run it through?

I assume (not familiar with the fuel bulb setup on this boat) that the bulb is normally stiff when it is running? That is, that it is in the normal fuel line and when the pump pressures up after priming with the bulb that the pump then keeps it inflated (normally, that is)? If that is the case, I think that may rule out a fuel issue and we are again looking at your pump or one of the two separators (unless there is something else before the bulb in the line). You can get a barb and take each separator out of the line to see if the pressure improves or ruling those each out in turn. Then you are back to a bad pump, I think.

 

[ajaquino]

I just got a new fuel lift pump under warranty and put a clear fuel filter before it after the fuel bulb. I changed fuse as well as it was burnt out. Question...is the fuel lift puml continuous? Im wqtching the clear fuel filter and i dont see any movement at all. I also have a micro fuel pump on hand and wqs thinking is it possible to replace lift pump with this.

 

[tdonoughue]

First thing I would look into is why the fuse blew. You may have a short or something that is stopping the fuel lift pump from working properly.

Most fuel lift pumps are continuous these days, now that they are electric. If you are watching the fuel filter, it may be hard to see any fluid movement--there should not be any contamination or bubbles in it (and those would let you see the flow). Are you seeing air in the filter and it is not going away? Or just fuel (that you can't tell is moving)?

Pull the fuel line after the separators and put it into a bucket. It should pump nice fuel into the bucket.

 

[ajaquino]

Correct from the clear fuel filter all i see is half fuel and half air that doesnt go away, no bubbles. When i put ignition on i can hear fuel pump on for few seconds. I will try and disconnect after separator and see if fuel flows into bucket.

 

[ajaquino]

Just tried this morning pulling fuel line after separator, no fuel is returning into bucket. Thoughts?

 

[ajaquino]

 

[ajaquino]

Thats how this boat was setup....fuel tank to bulb to lift pump...to pump reservior and back to fuel tank. If you see from photo i disconnected line after water separator reservoir and into a bottle. Nothing flows out...i added clear fuel filter to see if fuel is really flowing

 

[tdonoughue]

Time to check the electrical connection to the pump. Pull that and put a multimeter to it. See if the current to the pump is going on and then immediately off like that. If there is no fuel flowing into your container, that explains why your engine is dying. No fuel. And if you had a blown fuse, there is probably a reason for that--they don't normally just rot or anything. Either the prior pump was frozen or there is a short or something. If you are not hearing the new one after a few seconds and it is not pumping anything, that is your problem--there at the pump.

 

[Weeb]

Make sure the bulb Isn’t bad. It might be letting the fuel flow back.

 

[ajaquino]

So tested fuel pump connection this morning and yes no power. I should have power with ignition on or do i need to start boat? (Sorry stupid question). Tested battery and other terminals and there was power. Is there a wiring diagram for Mercury Optimax 200/250 engines that you guys can share? Is there a main fuse box or something like cars on a boat? Sorry this my 1st boat and 1st time im learning about boats. Thanks for all the help. Is there is quick solution I can do to get power to fuel pump?

 

[ajaquino]

Update: found main fuse...all fuse are good condition and tested. Any suggestions next?

 

[tdonoughue]

I don't know about whether the boat needs to be running... But there is an easy way to figure that one out. Put your hose in your container and crank the engine. It should at least be pumping then, regardless, right?

I don't have a wiring diagram. Heck, never even seen a Sugar Sand... Sorry. You obviously checked the fuses (and if it is going for a moment and stopping, it is not a fuse, right?). You could make a temporary connection between the fuel pump and the battery. See if it starts and keeps running then. That would narrow the issue down to whatever circuit or relay is running the pump.