fuel plumbing advice--suggestions--

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fuel plumbing advice--suggestions--

Postby jethro » Thu Dec 13, 2018 2:39 am

Hi all--- The good news is- my engine is going great. Just have a "how-to" type question.
I am running a ford f-350 chassis with a 1-st gen C I installed. I upgraded the fuel pump to a 2-nd gen with the piston.
I just did it simple. Ran a 3/8 copper line from the engine back to the rear fuel tank (and a 5/16 return line)
I got a NAPA fuel strainer that has a screw-off canister and quick drain on the bottom. I installed it just forward of the tank
on the side of the frame forward of the rear wheel. Everything seems to be working fine.

However---- If I want to drain the QD or change out the strainer element--- I need a way to do it WITHOUT losing the prime
or letting air in the line. I first inclination was to install a stainless ball valve into the strainer where the fuel line goes out. That would
isolate from strainer to engine--- but Its a downhill slope from the strainer to the tank about 2 feet away. Seems like I would need
something like a manual pump in that side of the line to suck the fuel up from the tank and refill the strainer and blow out any air
bubbles before opening up the ball valve on the front side. Are there any small , simple but reliable manual pumps for this purpose ?
Like a better version of a plunger pump from a coleman lantern ----- It would have to be something that represented NO flow
resistance when not being used.......


As an alternative--- do these fancy Airdog type electric pumps have any provision to self prime/purge after a water drain or
filter change ????? and--- if the airdog thing fails--- will the engine fuel pump still suck the fuel to the engine ? Are there any
tangible benefits from an airdog type pump ?
(my power is only turned up very slightly--- still using the stock smallest injectors for MPG)


Aircraft engine use little piston pump primers that work like the colemon type. better quality ---


How do yall do water/filter dumps and not get air in the lines.........


Thanks ahead of time

Tim
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Re: fuel plumbing advice--suggestions--

Postby Remps » Fri Dec 14, 2018 6:24 am

You could add a couple Y's to the fuel line between the tank and your strainer, and run an electric pump in parallel there. Then there is no way it could block fuel flow, and you could use any pump you wanted. You may or may not want a check valve between the Y's on your original line to prevent any backfeed of pressure. Only I can figure to get almost all the air out of your filter housing is to add a bleeder at the top output somewhere. Then probably chase some of it out of the factory bleeder on banjo bolt, then burp the injector lines.
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Re: fuel plumbing advice--suggestions--

Postby PToombs » Fri Dec 14, 2018 6:09 pm

I have Synthex plastic air line on my truck with a 1/2" ID from a sump. Under the cab I have a Racor water separator with a ball valve on each side of it. The Racor is an element with a clear plastic bowl, so it can't be prefilled. I make sure I have over 1/2 a tank so fuel is above the Racor, shut off the valves, replace the filter and clean the bowl, then reinstall it. I then open the valve from the tank, loosen the holding bolt a little until fuel fills the bowl, then I tighten it. I then open the engine side valve, and start the truck. I stay right there and when it starts to stumble, I floor it and it skips a little and burps the air thru with no problems. (so far ;) )
Hope this helps you Tim!
pete

Just enough power to break everything behind the crankshaft.
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Re: fuel plumbing advice--suggestions--

Postby jethro » Fri Dec 14, 2018 9:47 pm

Thanks PT and others----
I have changed the fuel strainer on my bosses 8.3 motorhome by just filling the bowl till running over--and carefully screw it back on.
so far -it hasn't gotten air. He was on the road and tried draining the bowl with the little tap on the bottom--- (to let water out)
and got air in it and it wouldn't start. Had to call mobile road svc.

PT--- you said something that gave me an idea. Now- the piston fuel pump is higher than my strainer. but the tank is
lower. If the strainer was at the highest point -- it would be less likely I would get air. The strainer has4 threaded ports.
I am only using 2 of them--- I wonder if I could put a copper tube in one and run that tube up high and use it like a standpipe.
Maybe put a ball valve on the end. If I could pump the fuel up the tank like and let it fill the strainer and then climb up the standpipe--
that allow the air to go up and out the top of the strainer.

If I could find a centrifugal fuel pump--- that should allow suction fuel through without any resistance when the impeller is not turning....
and be able to draw fuel up and purge the strainer when it is turning...… would that work ?
Tim
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Re: fuel plumbing advice--suggestions--

Postby PToombs » Sat Dec 15, 2018 6:27 pm

If the strainer is the highest point when you open it the fuel will drain to the lowest point and you will have air in it.
Is the strainer below the fuel level in the tank? If it is all you would have to do is put a valve in the 2nd outlet port to bleed the air out thru. With my setup I don't even have to bleed the air out of the Racor, I can open the valves and start the truck and floor it when the air gets to the pump/ Injectors and at higher revs it will push the air out before the truck quits.
When you say centrifugal pump you mean a vane type pump? Not sure if that would work, if the vanes are stuck or stay out it will restrict it.

If this is that big of a deal maybe you should invest in a FASS or AirDog pump. They self purge air from the filters back to the tank, plus they push the fuel right thru the IP so no bleeding. You can get rid of the existing filters and have the water separator and the final filter right there.
pete

Just enough power to break everything behind the crankshaft.
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Re: fuel plumbing advice--suggestions--

Postby jethro » Sun Dec 16, 2018 4:13 pm

when I said centrifugal--- I don't mean a vane pump--- I mean a fixed vane like a turbocharger. No valving--- so when its not turning--
its a free flow through deal. They usually are mounted in the bottom of the tank--- against the bottom. Not sure if I could find a 12 v one.


I see some of the strainers have little piston plunger pumps built into the upper housing. Mine does not though. I guess I will have to
keep thinking on this one. Will check into the Fass and air dogs.


T
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Re: fuel plumbing advice--suggestions--

Postby PToombs » Sun Dec 16, 2018 5:39 pm

I know what you are talking about now, I have seen them as water pumps.
A filter head with a primer pump is a good idea too. Probably way cheaper than one of the pumps I mentioned. ;)
pete

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