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BF50D low pressure fuel pump out put pressure

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Iceman12

New member
I have a BF50 D (S#BBEJ1012938) that dies after running approx. 45 min. Put a high pressure gauge & diagnostic equipment that determined that the fuel pressure was dropping off when the engine died. (no alarms). The HP fuel pump & EMC are new. When I attempted to start the motor, I can hear the pump run for 2 sec. I installed a low pressue gauge @ the outlet of the LP pump, reading 1/2 to 1 1/2 psi. I cannot find what the pressure should be in my factory manual. This seems low, does anyone know what the pressure should be? If I reved the motor up it did not change much. I ordered a new pump (16700-zz5-003) & installed it. the pressure is not much better. (this is with a shop tank connected directly to the LP pump). While on a river test, the pressure will slowly climb to 3psi at different rpm runs. the motor did not die but IMO, the pressure is too low. The LP pump & push rod are non adjustable. Your thoughts.
Iceman
 
Is there a restriction in the fuel line somewhere between the tank and the pump? Plugged/restricted LP fuel filter? Primer bulb hard or soft when engine quits? Have you swapped fuel lines? Hasn't happened to me yet, but I've heard of fuel lines collapsing internally. Bit's and pieces in the LP filter might provide a heads up here.
 
Ybor
Alan Hicks said:
Is there a restriction in the fuel line somewhere between the tank and the pump? Plugged/restricted LP fuel filter? Primer bulb hard or soft when engine quits? Have you swapped fuel lines? Hasn't happened to me yet, but I've heard of fuel lines collapsing internally. Bit's and pieces in the LP filter might provide a heads up here.
Click to expand...
Alan,
I apologize 4 the delay, been very busy.
As stated in the my original post, I hooked a shop tank directly to the L/P fuel pump & installed the L/P Guage within 3" of the outlet. The shop tank was sitting on the back of the pontoon boat to alleviate any fuel lift issues.This setup IMO should have eliminated fuel line,filters,etc. I'm trying to get the correct output pressure as I could not find it in the manual. .5 to 1.5 psi @ an idle seems low with 3psi max while running (it slowly builds to 3psi).
Iceman12
 
Busy here as well. No big deal.
I misunderstood. I was thinking engine was on a test stand. Following your thinking now. Still, you haven't eliminated the potential for a collapsed line from the pump to the vapor separator. Not very likely, but when you're grasping at straws! If you could elevate your pony tank a couple of feet (on top of a rear seat back?), maybe run a line from that right to the vapor separator (by-pass LP pump)? Just tossin ideas..... -Al
 
Alan,
To install the L/P guage, we had the fuel line off & observed no issues with this approximately 6" piece of hose going to the VST.
With all due respect, moving the shop tank to a higher location is not duplicating normal running conditions. The shop tank eliminates the motor fuel lines,connectors,filter,etc., I'm just trying to find what the L/P output pressure should be.
Iceman12
 
No respect necessary:), thick skin here. I was just thinking you might be able to eliminate the LP pump as the source of your headache. If the motor behaves normally with an elevated "shop" tank, there's little doubt your issue is somewhere from the tank to the VST. If there is no change, you know there's something going on with the VST.

Thought being that simple test might be quicker/easier than looking for a fuel pump pressure spec? -Al
 
Low pressure will fluctuate with the float level control opening and closing, if you crimp the hose going to the vapour separator you should see pressure increase to around 5psi
 
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