With my new motor install one pump was real hard to prime . After getting it primed its been working fine But . it did it again the other day.Low on gas.. So I had a extra pump and put it on got it primed and is working OK now . The pumps are the areomotive ones everybody was having problems with.The reason I have a spare .If you put your finger on the inlet it will suck on your finger

Someone told me to put a ck valve in line so it want loose prime .They called it a ck valve or anti siphon valve or anti drain back valve.

I see areomotive makes one . Do you suggest using one and could it restrict flow . the line are #10.

The other thing I was thinking about if its loosing prime maybe it has a leak on the suction side and sucking air?


What do yall think? . Any suggestion on the valves ?

Thanks for your input.

Rob

I take it we are talking about electric pumps. This is not just a problem associated with Aeromotive pumps. All electrics do not like to suck fuel. Unfortinatly, in a boat they must. Aeromotive does have a new pump which can be installed in the tank. That will be the final solution.

I'm no marine mechanic, so if someone wants to say I'm
full of it, I can't blame you.

What I have done is built a number of fuel injected four wheel drives over the years. I've found the only way to really
be sure an electric pump does not lose prime over all altitudes and temperatures is to use an in-tank pump. Now we don't want to do that on a boat. And believe me, I've spent
endless man-hours trying to make external electric pumps
reliable on my 4x4's and it ain't happening (remember, I said
this includes 13000ft altitudes and 120 degree temperatures).

That's why I find especially interesting, and really like, how
Merc uses the diaphragm mechanical pumps on my 575SCi's as the lift pumps to feed the electric fuel injection pumps. The good old diaphragm pump is the ultimate way to get the fuel FROM the tank. The electric is the best way to pressurize the injectors. When a buddy of mine upgraded his 575's and removed the diaphragm pumps to put in the latest in hi-zoot electrics I didn't have the heart to tell him that I didn't think really highly of that strategy.

It costs big bucks, but you can get the pieces to equip any engine with the diaphragm pumps.

Pesky Varmint

I don't think anybody is going to put a electric fuel pump inside a boat gas tank. Could be wrong .The areomotive pump will suck pretty hard on your finger .Just wondering maybe I have a leak that might be causing it to drain back?

Anybody have any suggestions if a ck valve will work?

Strip, Can the pumps be mounted any lower so that gravity can help?

I have that problem and put the aeromotive -10 check valve on the output of the pump so as to not make it any harder to suck. Helped if the boat only sits a few days but will still have problems if it sets for 2-3 weeks.

Note: I have the 575sci and removed the diaphragm pump and that's when it all started. I wanted to put the diaphram pump back on in front of the aeromotive but the plumbing looked too restrictive.

The pump is in the factory location.The fuel water separator is mounted up high in the factory location. thats part of the problem . I figured that this pump might of been week so I swapped it out.Its Working ok now but I don't think the problem is fixed?

The ck valve might be a band-aid that works??

Thanks

Rob

I have an aeromotive pump on my motor as well. I use a Racor filter/fuel-water separator assembly. What I do is use a cheap inflatable boat hand pump to put a small amount of pressure in the tank through the vent line, then vent off the top of the filter bowl. Once that filter bowl is full, it does not drain down due to its own vacuum, and it is up high enough to give enough suction head to the pump to get it to take. I installed a fuel pressure gauge so I can see what's going on, and it works like a champ, all the time. I have left it sitting for over a month, and had no trouble priming. If I need to change filters, I reprime, but that's like once or twice a season.

Rob: I've never noticed this problem with the layout that I think I see in your picture. The big fuel water separator acts as feed for the pump from a much higher location than the tank, so why would this layout lose prime? What is the blue filter housing in front of the pump? If it's just the stainless mesh why do you need it after the separator?

tcelano thanks for that idear.

Tom it came with the whipple kit. It had the areomotive filter before on it . I guess its a smaller micron?Before it was after the pump for when the areomotove pumps took a dump . [they had a problem with there glue on there magnets coming loose and stoping up the injectors ]

Thanks

Rob