Does fuel pump psi matter a lot?

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Does fuel pump psi matter a lot?

Postby 2poodles » Sat Jun 29, 2013 6:24 pm

We have a 1996 Chevrolet G30 Van/Short Bus with a 6.5L V8 Diesel engine that we'd like to add a veggie oil to. We recently bought a 30 gallon plastic tank with a p74735m fuel pump/sending unit off of a 1994 Dodge Ram 1500 (Gas) with a V8 engine. We don't think our bus has a lift pump. We were told that gas tanks generally have fuel pumps that are too week, but the one that we got seems to be too strong. We looked up the amount of fuel pressure the different tanks output on autozone.com. The fuel pump from the bus's original tank is rated between 6 to 9 psi pumping at about 35 gallons per hour and the new tank we got for the vege oil is rated between 80 and 90 psi at around 50 gph. Is this right? That seems way to high for a gas fuel pump. We can always get a new fuel pump for our new tank, but do we need to? Does it really matter? Is there such a thing as too much fuel pressure coming from the tank?

All comments and criticisms are encouraged. Thanks :)
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1996 Chevy G30 6.5L Diesel (Van / Short Bus)
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Re: Does fuel pump psi matter a lot?

Postby SunWizard » Sun Jun 30, 2013 9:55 am

Any diesel fuel pump before the IP is called a lift pump. The pump output on diesel and veg. oil will be different than what its rated on gas. Yes it matters, the pump should put out within the specs. for your original setup, and it sounds like yours is way too high. Too much pressure can make it run bad or damage something.
YVORMV - Your veg. oil results may vary.
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Re: Does fuel pump psi matter a lot?

Postby 2poodles » Mon Jul 01, 2013 6:35 pm

OK great thanks so much!
What about the fuel filter manager psi?

We did a little bit more searching and found that the fuel pump / lift pump attached at the bottom-front of the engine outputs about 8-9 psi, so the thought crossed our mind to just use this lift pump instead of getting an additional one. However, to do this we will probably need to get an additional 3 port valve in addition to the 6 port valve we already have in order bypass our Chevy G30's original fuel filter which is located directly above the engine right behind the injector pump (IP).

We ran into a hiccup though when we found that our G30's fuel filter is part of a "fuel manager":
http://www.thedieselstore.com/template/ ... dIXBxUju1E
this "Fuel Manager Complete 'Top Load' Assembly" is a fuel filter & water sensor/seperator and has the following OPTIONAL features which I'm not sure whether or not our Chevy G30 utilizes:
In-unit heater. (heater only heats fuel to 45º F (then shuts off) & NOT designed for use with SVO or WVO alternative fuels)
Electronic "water-in-fuel" indicator.
Hand primer.
Electric lift pump
Filter change indicator

The psi of the lower lift pump is around 8 or 9 psi, but we don't know about the psi coming out of the fuel filter/manager up top.

Do you think the fuel manager is utilizing it's built in lift pump?
Does anyone know the psi needed before sending fuel to the injector pump?

Thanks so much! :)
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1996 Chevy G30 6.5L Diesel (Van / Short Bus)
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Re: Does fuel pump psi matter a lot?

Postby 2poodles » Tue Jul 02, 2013 12:52 pm

OK, so our Chevy G30's Stanadyne Fuel Manager (stock fuel filter / housing) just has a heater and a water sensor. It does not have an additonal lift pump. SO now all we have to do is just make sure we're supplying 8-9 psi to our fuel injector.
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1996 Chevy G30 6.5L Diesel (Van / Short Bus)
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