J240

Hello all I have a 454/330 with minor bolt on parts that is losing fuel pressure above 3300 RPM. I have a holley RED pump with a Fram high flow water seperator/filter. It is wired with the Painless wiring fuel pump relay kit. At idle I have 5.5 PSI. Getting up on plane and til about 3300rpm I have 5.0 psi. When I throttle up past this, pressure drops to 4 - 4.5 psi. Full throttle is at 4600 RPM at 4.0 psi then after a minute or two drops to zero so I back off and pressure comes back up. All fuel line is new 3/8 I.D and the pump is one season old. This is the first season with the fuel pressure guage so I could see what was going on . Is this pump too small?? Could this be affecting my full throttle rpm as the boat is a 24' BAJA with a 19 degree pitch prop which should be over revving the motor if anything. thanks in advance for any help!!

Tinkerer

check the fuel pick up in the tank for blockage. change the fuel / water seperator. why are you not running the stock fuel pump?

baja27

J240 , first off you need to toss that fuel pump. They are total junk. The problem your having is when the secondary's open up the pump can't keep up with flow rate, that's why your presure drops. Hope this helps.

mltdwn12

J240, I carry a red pump as a spare. I normally run the Holley blue pump on a blown 509, two 750's. When I was having problems keeping the blue or black pumps alive, the red pump always got me home. But it only idles at 4-5 pounds pressure and any extended happy throttle nonsense you'd see the pressure going down and have to back out of it. I run -8 line from the tanks (cat with tank in each sponson) to IMCO valve. Then to a big water/fuel filter, to the pump, then to a y-block where it goes to 2 -6 lines to feed each carb. I also run the Painless fuel pump relay. The relay solved my pump problems as well! I think you might have soemthing going on causing a restriction. That pump should keep about 4 pounds on your motor at that rpm. You might check the bypass valve in the pump body, anything small can hang one open a little and not get you full flow to the carb. Most of the Holley pumps though have a small brass screen at the inlet. Check to make sure nothings clogging that as well.

Craig

Turbojack

Chances are you have a check valve at the tank where your fuel line connects to. I think Coast Guard requires builder to install this valve but it restricts the flow.

J240

Guys Thanks for the responces! I"m running the electric pump because the motor is a genV with no boss for the mechcanical fuel pump. I've change the water seperator and also the anti_ sipon valve is removed. The pump screen looks clean and flows fine it will run all day long at 5.0 psi under 3300 rpm.
Baja27 I'm leaning toward your theory that the pump can not keep up with the fuel demand. I sent HOLLEY tech a e_mail describing the problem to them to see what their thoughts are.
So I'll wait and see, I know those pump do not like to suck up out of the tank. Thanks again ,keep any ideas coming and I"ll let you know what HOLLEY says.

J240

Back from a weekend of wrenching and testing. I spoke to holley they suggested the Holley Black pump with regulator. I installed the black pump and regulator and now have 7.0 PSI at idle and 6.5 at WOT 4600RPM. Went out for the first run 10 minutes into it fuel pressure drops to zero, throttle back and pressure did not come up shut down pump felt hot , waited a minute statred back up pressure up to normal. Drove around under 3500rpm pressure stayed up boat ran great. Went offshore for about 45min- 1 hour no problems. Came back in the bay throttled up and i could make the pressure drop if i went over 3800rpm then pulled back to 3500rpm and pressure would rise to normal ?? It seems to happend for no reason and under different conditions. Another time I went WOT and pressure stayed up and it ran great I could not make it drop at all no matter how much I stayed into it. So I went home and pulled the pickup tube it was very clean. Now I have no idea or what to do any suggestion would be well appreciated . This is very frustrating!!!

Tinkerer

Any chance you have something in the tank that is blocking the pick up sometimes???

Bulldog

Could it be a cracked suction line???

Griff

The electric pumps are cooled by the fuel that runs through them. Sounds like it got hot because it wasn't able to get any fuel through it. I would lean toward a problem with the tank pick up.
Have you had a FULL tank of fuel when you've been losing pressure?? or maybe just a half tank or less?? I would test with a FULL tank and see how the pressure is then. If it stays steady then its something to with the tank or pick up. If not its probably an obstruction somewhere prior to the pump. Who knows, maybe you've got something rolling around in your tank.