Correct fuel pump

[Bill]

This is a Bosch pump from the early '70 's.

I am thinking it will work on a 78 Spider to replace the 3 hole pump.

Will it work as a replacement and if so, what modifications are needed?

[Roadtrip]

Bill - The early 70s SPICA systems used the early Bosch 2-port pumps like the one in your picture. However, those systems had a separate pressure relief valve integral to the front fuel filter. In the filter assembly, the pressure relief is downstream of the filter element. The pressure relief occurs at 17 psi.

The later models had the three port pumps with a pressure relief valve built into the pump itself and no pressure relief in the front filter assembly.

Now, to your question. Physically, you can easily install a 2-port pump in place of a 3-port pump. You will need to block off the line from the PRV port on the pump to the fuel return line. However, now you have no pressure relief, should it be needed. If you want to use a 2-port pump in a 3-port system, I think you should check the fuel pressure after installation. In order to do this you must use a "T" fitting placed between the front fuel filter and the engine's fuel injection pump. DO NOT take a "deadhead" reading. It will NOT give you a correct reading because the pump is capable of producing a very high pressure if not regulated. Fuel pressure should be 14-17 psi or so with the engine running (alternator providing current), and, of course, the fuel low pressure light should be off whenever the key switch is "on."

I normally do not recommend using the old-style Bosch pumps, especially used ones, because their condition is usually poor or bad. I've bought a couple of them cheap off ebay and one was a leaker and the other worked for about 6 months before shorting out. Even a NOS pump may have aged seals. I haven't used any so-called new "rebuilt" pumps, but they are unreasonably expensive. I have heard of some people successfully using the Master E2000 fuel supply pump from Autozone. In any rate, you should check the fuel line pressure to be sure it's not over 20 psi.

In my opinioin, the best substitute is the fuel supply pump for the L-Jetronic Alfas. However, these pumps do not put out quite the quantity of the old-style pumps. To compensate and get the pressure back to 14-17 psi, the fuel pressure regulator restrictor in the outlet fitting on the injection pump has to be soldered up and redrilled with a 1/16" hole. This will bring the pressure back to spec. Plus, the L-Jetronic supply pumps are very reliable and long-lived. This is what I have on my 74 Alfa.

[turbolarespider]

John
Are you sure about that? I'm pretty sure that the SPICA needs fuel delivered to it at 45psi...

Side comment- on our turbo spider, fuel injection pressure is a delta of 39 psi, which means my peak rail pressure is about 53psi. I use a later 2 port SPICA pump, and it works perfectly. Jim Steck tells me that the pump is good for about 250hp worth of fuel at the pressures I run at...

Eric

[Roadtrip]

No. Fuel pressure for SPICA should be no more than about 20 or so. According to the Alfa SPICA factory manual, the pressure relief is set to "16-18" psi.

On your turbo, are you using a SPICA injection system? Are you using a supply pump with the inlet and outlet in an "L" shape like the one pictured, or is it the one that is shaped like a cylinder with the inlet and outlet in a straight line? I think you must be talking about a L-Jet system if you're talking about a "fuel rail." Spicas don't have fuel rails. EFI systems are in the 50 psi range and they rely on the supply pump to provide that pressure. The SPICA FI pump has pistons and plungers that put out about 400 psi to the mechanical injectors, but only needs about 15 psi from the supply system.

As far as the potential output of the old-style Bosch pumps . . . yes they can put out 45 psi at least, but you don't need or want nearly that much pressure in a SPICA system. Besides, unless you're using high pressure fuel line, it's dangerous.

[turbolarespider]

No, it's more a custom EFI system on our turbo. Virtually all EFI systems that use typical vacuum pressure regulator run at a delta pressure of 39 psi, so when I'm under 13 psi boost, the rail is 52 psi vs atmosphere.

I'm using one of the straight through pumps. So far, I've not found its limits on supply. And I'm running way too much fuel at times...

Eric

[montelatici]

I have heard of some people successfully using the Master E2000 fuel supply pump from Autozone.

The Master E2000 is a straight through pump with a 95 psi cutoff and in its standard usage, I believe a Ford from 83-90 it is supposed to provide 70 psi to the system. It has much smaller fittings than the Alfa standard pump (and filter) so perhaps, and this is only intuition, it may result in providing the appropriate flow for the Spica. But it is only intuition. Can anyone speak more authoritvely on the subject as at 79 dollars it would be an economical solution as it is about the same size as the stock pump, albeit no 90 degree turn.

[Roadtrip]

70 psi would, of course, be WAY too high for a SPICA system. SPICA injection pumps need 15-18 psi only. I suppose you could modify the out restrictor and lower the pressure. But I don't know what the hole size would have to be. You'd have to get an in-line fuel pressure gauge and "dial-in" the pressure down to 15 psi.

A Bosch L-Jetronic supply pump is only $160 and needs a 1/16th inch hole in the restrictor. By contrast, a fuel pump for my Jeep Grand Cherokee 4.0L cost close to $500.

[montelatici]

Bill,

I have a three outlet pump from a 76 Spider. I would be willing to trade for a two outlet pump that I can use on my 1974.

Alfredo