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Can I use an extrernal fuel pump as the primary..

2709 Views 17 Replies 9 Participants Last post by  Steve Wood
It looks like the walbro pump might have gone south. (No fp)The fuse for the hot wire is blown, and unless the relay is shorted, it is looking like the in-tank pump is done for.

I have an external bosch pump that I removed, because I didn't think it was needed, and I didn't like the fact it was sitting directly over the stock location muffler I had just installed.

Question, can I just take the in-tank pump out, and use the external pump? (outside the tank)? I thought I heard that the external pump wouldn't draw gas, and that it needed another pump in front of it.
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You basically heard right...they don't suck, they push....quite Unlewinski.

Why not go for one of those Racetronix deals?

Could be a shorted hot wire too.
Did you try hooking the F/P up to the stock harness to see if it works?

Give em' hell!
just unplug the pump at the tank and put another fuse in and see if it pops too if so then you know its in the wireing.

external pump by itself will be fine as long as you do away with the intake pump...once its primed the pump pushing the fuel sucks the fuel out the tank. just as any electric pump.
I've been running a Bosch External for about 12-13 years. I just pulled out my in-tank pump when it eventually crapped out. They were mounted in series. My Bosch pump is a puller, I don't need another pump to help it. Just make sure you mount it at least level with the tank. I have mine mounted at about the bottom level of the tank. It makes it easier to pull.

I believe all the external Bosch's are pullers. Steve has me confused at this point as to whether they all are!
It doesn't matter anyway, as it's been purrrrfect for all these years. Road racers use these pumps a lot and call them 5 bar Bosch pumps. I've heard that they are rated at around 54-57 gallons @ 70-72.5 psi; maybe as high as 90 psi. My pump is a #216. Inside the tank I just used FI hose and a stock filter attached to it at the bottom of the tank. The filter is mounted vertically, so some of the crapola drops back into the bottom of the tank (hopefully), when the engine is shut down.

I've been running without the prv valve for about 3-4 years, ever since it went out. You really don't need it, since I can hit the starter before the relay stops and it will fire in a few cranks.

[This message has been edited by CaPPY (edited April 15, 2002).]
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I agree with Cappy, I have have used a external boush and SX pump for a number of years and yes it's a good idea to mount it even with the tank. Yes these pumps are pushers but I have not had a problem with them.

Good Luck

Neal Whyte
87 GN 9.71 @ 140
Free your mind and the rest will follow
I thought I understood it was mounted, in Tim's case, above the stock location muffler? Isn't that above the tank? I believe these pumps are pushers and must be gravity fed?

Steve the old set-up had an in-tank 340, feeding the Bosch mounted above tank. I've since removed the Bosch.

I'll go ahead and remove the 340 from the tank, and use the Bosch as the only pump now.

Thanks everybody!
Just an addendum: Spoke to a Bosch tech today, the curiousity was killing me, all the externals are PULLERS!

It shouldn't matter then, at what angle or height they are mounted. Mine is definetly a Porsche application.

Another pump is not required in the system.

I gave him the # of my extra backup pump and his specs were the same as what I quoted earlier with the other post. He said Bosch doesn't quote specs, but since I told him what I remembered, he acknowledged that I was dead on. HTH

[This message has been edited by CaPPY (edited April 15, 2002).]
Well I'm pissed! I got back to the shop after work, and the idiots had put an ac delco E-3211 in the tank! The boss (my buddy) said it would have been a lot less money to put the in tank pump in, and the parts guy told him it was an 85# pump.

Well the afpr was set @ 35# when I got there. (old pump pressure setting)Turned it way, way up to 42# taped the fp guage to the window, and at WOT, 10 psi it merely holds steady.

Question now is will the bosch even work, or is the in-tank pump a restriction? I'm guessing it should be ok....

Then I will need to find a place to put it, that is not over the stock muffler.

Grrrr. I'm not even going to back over there now (next door). Things would get ugly 'cause even though we are good friends, I'm too riled up at the moment to trust myself.

On second thought-screw it! It's time we went out and had a few beers together. I'm not ALL that out of control.

[This message has been edited by Turbo_Tim (edited April 15, 2002).]
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the customer should always state what he wants done...leave nothing to chance...remember, you know more than they do and that is a scary thought!

If you want to run an inline put a bulkhead fitting in the top on the tank and run a line down, some sort of pre-filter might not be a bad idea (>100micron). The racetronix pumps are good but not much better than a walbro 340. I'm putting them in my car soon.

If you do go with an inline I've got some 6AN fittings for the fuel pump that I'm not going to use anymore. I'll make you a good deal.
Yes the customer is always right, 'cept when the foreman thinks he knows more about Turbo Buicks than I do.

The tank is comming out, and Red's XP is going in, along with his volt booster. I've never heard of anyone having a problem with either...

Guess I could sell the Bosch. Anybody here interested?
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Talking about external pumps, I use to have one on my old hot air. Every spring I would get the factory injectors cleaned, seemed to help. Anyway, one spring I went down to Canadian Tire and got them to clean the injectors. My external pump made some pretty good buzzing sounds. The so called mechanic, looked at me and said, "Your pump sounds pretty loud! That usually means it is on the way out!"

I looked at him and said, "Yeah." While thinking, no buddy when the pump doesn't make any noises is usually when we got a problem. Yet some of my gear-head friends would hear the pump and see the adjustable Fp regulator and put 2+1.6 together. All I got to say is, "Some people's kids!"

[This message has been edited by forzfed (edited April 17, 2002).]
the xp and xp+ are simply the same Walbro pumps that we all use...why do you need a volt booster?

Originally posted by Steve Wood:
the xp and xp+ are simply the same Walbro pumps that we all use...why do you need a volt booster?

Not being one to waste money, I'm going to wire the volt booster so at WOT, my windows will roll up and down a bit faster.
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Go buy yourself a relay and hot wire the windows...

All the volt booster can possibly do is add some more pop to the ignition which should not be needed but might help on some cars. Us old guys watched Conley run 7s on a stock ignition with no boosters so we doubt some things...on the other hand, John Spina has said it has helped some he has seen.

The pump flows enuf, Walbro 340,at 12 volts to go way into the 11s, and with a hot wire and seeing 13.5, into the tens. You don't need any more stuff that might fail.

I guess you might get brighter headlights, but again, just hot wire the lights....

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