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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: harley86 on August 26, 2011, 08:24:59 AM

Title: DD 8V71 prime pump
Post by: harley86 on August 26, 2011, 08:24:59 AM
Good Morning


I have been searching the archives about putting in a electric prime pump on my 77 eagle with a DD8V71N mechanical motor.

I was thinking of doing one of the following any advice would be appriciated.

1) Tap into the fuel line near the tanks maybe tee into the crossover line then into a electric fuel pump then to the top of the secondary fuel filter or the fuel line between the engine fuel pump and the secondary fuel filter.  I read that fuel pressure can damage the engine driven fuel pump would this arangment do this or is it only the suction side of the engine driven fuel pump I need to worry about.


2) Install a electric fuel pump between the engine driven ful pump and the seconday fuel filter. This would be a pump that would flow fuel when turned off.

In both samples the electric fuel pump would only be turned on  when needed to prime the fuel system.


Thanks Kerry
Title: Re: DD 8V71 prime pump
Post by: bevans6 on August 26, 2011, 08:48:04 AM
I just went through this and on the advice of experts I installed a low pressure flow-through pump in the line leading to the primary filter from the tank.  I used the 24 volt pump pictured.

Haven't tried it yet, but all assure me it will work...  :P

Brian
Title: Re: DD 8V71 prime pump
Post by: Stormcloud on August 26, 2011, 10:33:14 AM
Nice installation, Brian.

I should do exactly  the same. Where did you find the pump?

Thanks!

Mark
Title: Re: DD 8V71 prime pump
Post by: bevans6 on August 26, 2011, 10:34:12 AM
Princess Auto has them.

Brian
Title: Re: DD 8V71 prime pump
Post by: Busted Knuckle on August 26, 2011, 10:44:10 AM
Kerry,
Since in the US we don't have Princess Auto (or queens & princes either for that matter!) try NAPA. I believe that is where Clifford buys them.
;D  BK  ;D
Title: Re: DD 8V71 prime pump
Post by: luvrbus on August 26, 2011, 11:16:12 AM
Auto Zone has a better price than Napa unless you have a fleet account with Napa

good luck
Title: Re: DD 8V71 prime pump
Post by: Len Silva on August 26, 2011, 11:24:18 AM
I wasn't comfortable with the possibility that the flow through pump would restrict the fuel flow too much.  I chose to install mine at the tank and used a manual valve instead of a check valve just because it was cheaper.
Title: Re: DD 8V71 prime pump
Post by: bevans6 on August 26, 2011, 11:41:43 AM
Stormcloud, AKA Mark Morgan, is from Brandon Manitoba, a mere prairie stones throw from Winnipeg Manitoba, the home and heart of Princess Auto - and since he asked where to get one, that was the best answer - for him!  There's one just off the Trans-Canada, out near the airport.

Brian
Title: Re: DD 8V71 prime pump
Post by: luvrbus on August 26, 2011, 11:42:54 AM
Guys I can take the guess work out of it with that pump I have done a flow return a dozen times when I installed those pumps only one time did I need to change the orifice and it was wrong to start with it was a homemade job.
Only concerns I have about Brians pump is it is mounted under the exhaust manifold it may last forever with the heat or last one time but he has 2 pumps lol

good luck
Title: Re: DD 8V71 prime pump
Post by: Busted Knuckle on August 26, 2011, 11:52:53 AM
Brian my apologies I didn't realize it was Mark aka Stormcloud that asked. (I guess to be honest I didn't read who was asking, I just assumed that it was Kerry since he was the OP)

And I also stand corrected by Clifford as I thought he got his from NAPA!
;D  BK  ;D
Title: Re: DD 8V71 prime pump
Post by: luvrbus on August 26, 2011, 11:57:16 AM
I do BK but I have a account the the list price at Napa is little ruff lol so I send people to AutoZone that is about all I would buy there
Title: Re: DD 8V71 prime pump
Post by: harley86 on August 26, 2011, 12:22:04 PM
Thanks for all the help does this pump come in a 12 volt version
When I ask for a low pressure flow through pump how low does it need to be to avoid damage to the seals in the engine driven pump
Title: Re: DD 8V71 prime pump
Post by: luvrbus on August 26, 2011, 12:32:19 PM
Yes it comes in 12v best place to install it on your Eagle is on the cover of the back electrical panel plenty of places for a power tap and mounting of a switch.
I have a problem with a 10 lb pump blowing seals on 65 lbs pump I never had it happen before it doesn't have enough volume or pressure the fuel just returns back to the tank during the priming process just like it does with gear pump 

good luck
Title: Re: DD 8V71 prime pump
Post by: gus on August 26, 2011, 12:41:00 PM
Isn't it better to place a suction pump as close to the tank as possible?

That would also solve the heat problem.
Title: Re: DD 8V71 prime pump
Post by: Stormcloud on August 26, 2011, 12:45:46 PM
Thanks, Brian.  I can almost see Princess Auto parking lot from my place.

Next time Im there, I will pick one up.

Cheers!

Mark

Title: Re: DD 8V71 prime pump
Post by: bevans6 on August 26, 2011, 01:14:22 PM
ideally you would put a lift pump inside the tank, but that ain't gonna happen any time soon...  ::)

I think that if the pump, which is for priming only, can draw suction from the tank, that's enough and all it has to do.  If I were designing a permanent, full time pump solution it surely is not what I would use.  You are right, it's nice to have a pump push instead of pull, but the mechanical pump, which isn't a particularly modern design, pulls from the tank no problem.  We'll see what it does when I try to fire it up.  I'm more worried about vibration than head on mine, I can always move it somewhere else or put a heat shield on.  I was thinking of not mounting it at all, just letting it hang from the line.  I have a pump in one of the race cars that has just been hung on the hose for 8 years now, it seems happy as pie!  That steel braid lined -8 hose is bloody tough to bend in tight turns!

Brian
Title: Re: DD 8V71 prime pump
Post by: papatony on August 26, 2011, 01:18:51 PM
 The 80's and 90's Cats had a hand pump built into the filter. They work great and don't outside power
Title: Re: DD 8V71 prime pump
Post by: belfert on August 26, 2011, 02:17:40 PM
Quote from: papatony on August 26, 2011, 01:18:51 PM
The 80's and 90's Cats had a hand pump built into the filter. They work great and don't outside power

The Racor fuel filter housing on my bus has a built-in primer bulb.
Title: Re: DD 8V71 prime pump
Post by: gus on August 27, 2011, 09:23:07 PM
I think the original mechanical pump is much more powerful than the generic electric auto supply store types. Every one I ever had said to mount low and near the tank, they do push much better than they pull and this usually results in better priming.