Low pressure on electric fuel pump.

P

Pwebb

New member
I have not flown much over the last 4-5 years and am now just getting back into the air and have noticed that when pre starting of the engine when I turn on the fuel pump to high the pressure indicated does not climb into the green area like it used to in the past. I have not had any problem with it cranking but of course I'm thinking that it is starting to fail and do not want to need it while switching tanks while in the air.
I'm assuming that I should just swap out the fuel pump but wanted to get any input before ordering a new one. Is there a screen that could be getting clogged or other things I should consider first?
Thanks,
Phil
I have a 1966 14-19-3A with a IO-470F.

P.S. I used to be more active in this forum years ago and got distracted with Hurricane Katrina and am now getting back going.
 
My manual said that the electric fuel pump should be under the left front seat. I removed panels under seat but cannot spot the pump. Any other ideas as far as where it could be located?
Phil
 
I would run the pump, listen and track it down. (if you can put power on the a/c )

Which reminds me, can anyone comment on replacing the wobble pump on a 14-13 with an electric fuel pump? STC's, 337's or how to?

r
 
Larry, I would be most appreciative if you could email a copy of your 337 to ronmarks(at)gmail.com . Having the original wobble plus electric seems like a good idea.
thanks, ron
 
SoCalPlaneDoc said:
The pump in my -3 is in the left wing root forward of the front spar
Click to expand...

That must be along the same area as mine is as I see the fuel line leaving the gascolator and headed that direction. Thanks for that info.
What makes me wonder that possibly something may need to be looked at is due to the noise it is making. It sounds like it is running at a lower rpm and the after about 5 seconds or so it will start to speed up and the sound clears up to a high whine and finally start to get some pressure on the fuel pressure instrument. I only show it going into the 3-4 pounds or pressure. Does this sound normal to what you are experiencing?
Phil
 
PhilWebb said:
It sounds like it is running at a lower rpm and the after about 5 seconds or so it will start to speed up and the sound clears up to a high whine and finally start to get some pressure on the fuel pressure instrument. I only show it going into the 3-4 pounds or pressure. Does this sound normal to what you are experiencing?
Phil
Click to expand...

negative. mine starts briskly and, after a couple of seconds, begins to labor as the pressure rises. My normal practice is to shut it off when it gets to 5 but it possible could go higher.
 
Okay, thanks for that info guys. I will take off the front left wing root fairing to check it out.
Phil
 
I would put a pressure guage directly on the output of the electric pump,
and see how it behaves and sounds. Your description is just the opposite of the properly operating one
where high start load is followed by a low load ( high speed). Cavitation in the pump, or a relief valve opening,
or ??

Ron.. No way would I ever be without my wobble pump!

engine and electric pump failures aren't uncommon.. but you can see several posts where
guys have continued long flights on just the wobble pump and .5 psi.

Total electrical failures aren't uncommon, and jamming more electrical stuff on the
anemic generator system of your cruisair ? Well... you're and Elect. Engineer .

So then, "where's your parachute ? ? " I mean back up system.
 
Larry Lowenkron:
Thanks much for the fuel pump 337 for a 14-13. Your comment about a possible better way to plumb it are noted and I agree that some analysis and changes maybe worth looking into.

Larry(Blimpy): Yeah, generally the more redundant the better. I commented previously that: "Having the original wobble plus electric seems like a good idea." which is what LL's electric fuel pump 337 features .
In any case, I am encouraged by stories that some have "made it back" with only the wobble pump. As part of our Cruisair safety program, we should test if the hand pump will give the quart per minute needed to continue a departure or go-a-round. Otherwise it could be a sucker bet to continue a climbout with only the hand pump. BTW, the math is .6 lb/HP/hr(rich) X 150 HP / 6lb/gal= 15 gal per hr or 1 quart/min.
ron
 
thanks for the math... helps with my question about fuel use during climb out.
My guestimate of 17gph on the right side of wrong for planning porpoises.

Hope we get to see your bird flying !.

Had the "opportunity" to use the wobble pump pumping into "an open system"
Monday, when we were checking for contamination in the fuel system after
the partial engine failure.

It didn't take long to move a pretty good quantity of gas.
Even with a fuel line disconnected and pumping into space it is
possible to achieve 1/2 psi easily.

It would take some thick wall cast bronze cojones to continue a takeoff on just the wobble pump.
But I guess if we can manage an insanely placed flap lever and a coffee grinder gear mechanism
we can wiggle a wobble pump ! :D
 
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