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Fuel Pump Replacement

5155 Views 19 Replies 8 Participants Last post by  itlives
What do you think about replacing an electric fuel pump on a 79 SPICA injected Spider with a Carter 4601HP? This pump is 14-16 psi, 100 gph, with internal pressure regulator. I am a fan of Carter pumps. I have installed different models of Carter electric pumps (5 psi) on my carbureted MG and boat and I am pleased with both of those units.

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What is the cost of the pump? An oem will cost me about $160.00:eek:
Call Centerline. They have a new replacement fuel pump (not that blue cheap-junk Chinese pump they tried for a short while and gave up on) that's fairly inexpensive and proven to work well with a SPICA engine.

Hopefully they learned their lesson on Chicom junk from that episode.

Just as a reminder, the fuel pump requirements for a carb'd engine and a mechanical Spica injection are totally different. The Spica injection system is a medium pressure recirculating system. By the specs it would appear that pump may work. Ideally you'd like to see 15 psi and at least 1/2 gallon per minute open flow rate (for injection pump cooling). Operating a Spica injection pump on low flow and low pressure (less than 7 psi which is where the low pressure warning light illuminates) is a good way to cause greatly increased wear between the barrels and plungers.

However, again, I see no reason to go experimenting when you can get a proven pump and support one of our Alfa parts vendors.
Carter Pump

The Carter pump is available from Mancini Racing for $119.95. Shipping is only about $7.00. I got both of my other Carters from them. Last year when I converted my MG to a Weber carb most places wanted $120-$130 for a Carter 4070 pump, which is the one recommended by Redline Weber. I found Mancini online. Their price for that model is only $72.00. This year I got the same model for my boat.

I'm in the middle of my fuel pump swap as well. I did some research and found a Walbro (GSL395) that also matched. In the end I went with the Centerline unit @ $160. It was a few bucks more but there are several people running it so you know it will work. The Centerline unit is German made and looks to be of good quality.

There is a bit of hose and wiring mods to make it work but it is not too bad.

I was in Nashville last week.
Wiring Mods?

What type of wiring mods? Was the documentation for the installation ok?
The original Bosch has a nice connector on the side. The replacement pump has two regular wire posts. There are wire lugs included with the pump. I had to cut off the connector and add some wire (extend) to the orignal harness. No big deal. I got things finished up today, my low pressure warning light goes out now.

On to the next thing....
Replacing tonight

New fuel pump going in tonight. Wish me luck!!!:eek:
No joy

New pump but still intermittent light. The fuel diagnostics guide from Wes Ingrams site would tend to indicate a problem with the hose on the booster pump. What is the trick to removing it from the tank?????:mad::mad::mad:
I wrote that guide.

It's very easy to check the in-tank booster pump. First, put a fuel pressure gauge on the outlet pipe of the fuel tank. It IS permissible to deadhead check the in-tank boost pump. You should get 3 psi. Unless you know what you're doing, I do not recommend that you open a fuel tank without some competent help.

Also, depending on what the replacement pump is, you may have to narrow the restrictor in the outlet fitting of the injection pump by filling the hole with solder, then redrilling to 1/16".
Its good to talk to the author!

I have already opened the tank to replace the gasget in the head. It is a rebuilt injection pump from Wes would I still need to solder the fitting?.

The fuel pump is a new replacement from Centerline. Looks like the one in your guide.

I can HEAR the **** pump cavitate intermittently. This corresponds to the light going off and on.
The outlet fitting may need modifying. Wes does not modify the outlet fitting. He doesn't know what kind of supply pump you have. The supply pump should have a pretty even hum. I agree with you that it sounds as if the supply pump is not getting constant positive feed from the in-tank boost pump.

1. The in-tank boost pump is operating normally . . . i.e. the pickup screen is not blocked and the short connector hose from the boost pump to the outlet flange is in good shape and not leaking. With everything back in place, deadhead test the boost pump by connecting a short fuel line from the tank outlet flange to a gauge. With power on the pump, you should get 3 psi.

2. Put the system back together completely and turn the key switch on and listen for the supply pump. Go to the gas tank and remove the filler cap and listen to the inside of the tank closely. You should hear some dribbling from inside the tank. That's fuel from the return line going back into the tank. Although not common, the return pipe inside the fuel tank has been known to varnish up and stop the return line flow (commonly in cars that were stored for long periods of time with fuel still in the tank). The result of this is that the supply pump, which runs constantly, does not get enough fuel flowing through it to keep the pump and fuel cool, in addition to creating very high pressure in the feed line to the injection pump (very dangerous since the internal pressure relief valves in the L-jet supply pumps is over 50 psi). The fuel heats up in the supply pump and eventually creates a vapor-lock. The pressure then drops in the line, the low pressure light comes on, and the injection pump gets starved for fuel.

Now, if everything checks out . . . . . fuel filters all clean, in-tank boost pump providing a constant 3psi head of pressure to the supply pump, no kinks or internal defects in the rubber fuel lines, and the electrical connections to the pumps are all clean and tight and providing steady 12v power, then I would go ahead and narrow the restrictor, per the instructions in the guide.

I installed an L-jet supply pump about 4 years ago in my 74 Spider. Under engine load, I'd get an intermittent low pressure warning light with the restrictor unmodified. Once I narrowed the restrictor to 1/16" the pressure stayed at a nice 13-15psi regardless of engine fuel demand.

The problem with the L-jet supply pumps in a Spica application is that the delivery capacity in gallons per minute may be somewhat less than the OEM pump, hence the need to narrow the restrictor to keep the pressure above 7 psi.

That said, I believe the specs of various Bosch pumps is different, even though they may look identical on the outside. I don't know exactly what spec Centerline is stocking for a Spica application.

All of this sound real complicated, but it's really quite simple. These Spica cars are getting old now and most have had almost no preventative maintenance done to them. Things like rubber fuel line deteriorate from the INSIDE, not the outside and seldom get replaced until they're leaking, even though they've been sluffing off rubber bits internally for quite a while. Again, like the short little piece of connecting hose on the in-tank boost pump. If my car was equipped with a in-tank boost pump, you can bet that I'd replace that 10 cent piece of hose with a new one, just so I didn't get left stranded because I was too lazy to do a little PM on a 30 year old piece of machinery.
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What 12 years of storage will do.

This is the bottom of the sending unit in the fuel tank. Although it is a littly blurry, you can see why I have little wonder why the fuel pressure was low.


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Yuk. Looks like that tank was left to sit for a long time and a lot of varnish formed in it. Sounds like a trip to the radiator/tank shop is next.
Radiator/tank shop?

Are you thinking the tank should be pulled and cleaned?
You can visually inspect it through the sending unit hole, but, yea, the boost pump is badly crud'd up, the tank is too probably.
If it was me I would clean the pump screen and if that clears it up stop there.
might want to change the back filter too.
My 78 Spider has been sitting undriven for the past three years with only a 1/4 tank of gas. I was thinking before I start it I should remove the fuel tank and have it cleaned (steam?). I was wondering if anyone had any cautions on removing or cleaning the tank before I proceed. Thanks.
My 78 Spider has been sitting undriven for the past three years with only a 1/4 tank of gas. I was thinking before I start it I should remove the fuel tank and have it cleaned (steam?). I was wondering if anyone had any cautions on removing or cleaning the tank before I proceed. Thanks.
Beyond advising you not to smoke while working on it, no, there's nothing exotic about pulling a tank. It would be good to remove as much of the old gas as possible - pull out the sending unit, stick a hose down there, and either siphon, or pump out the old fuel (using an electric shop vac - not a good idea). Here's what I use:

It comes from Griot's Garage.

The key thing about cleaning a tank is to get all of the rust flakes and dirt out of it. IF it isn't rusted inside, you can probably get away with pouring in some solvent (gasoline?) swirling it around, and flushing out the particulates. If you do see rust inside, then chemical cleaning and coating is probably a good idea. Radiator shops traditionally do that process, though radiator shops are going the way of the covered wagon.
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I just cleaned an old VW tank. I've done it like this a couple times. It works great.
Get some muriatic acid and an old chain. You're going to make sure no acid gets out, that stuff is BAD! (Use some neoprene gloves. too)
I taped up the holes with Gorilla tape, put the chain in and pour in a little less than a quart. Tape up the last hole and swirl it around a few minutes. Empty and kill it with water. Rinse the tank with water and let dry thoroughly.
I use Master Series Silver to coat the inside with. There are other sealers (just do a quick search) but I like the MS Silver. After it's dry, you're ready to reassemble.

I came here looking for a link to the filter (buy ing or cleaning?)inside the Spica fuel pump - got side tracked. So, anybody that can point me in the right direction would greatly be appreciated!

Edit: After more looking, I have some work to do before posting questions! Thanks
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