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-   -   Moving the fuel pump forward near the gas tank (http://forums.pelicanparts.com/porsche-911-technical-forum/1011617-moving-fuel-pump-forward-near-gas-tank.html)

Sunroof 10-29-2018 07:21 AM

Moving the fuel pump forward near the gas tank
 
One of the quirks of the 1973.5T/CIS model is that the fuel pump in mounted in the rear wheel well and despite the claim that the pump has a check valve, every time you restart the car you have to draw the fuel back quite a ways to get it started. Listening to the engine when starting (without hand throttle and car warmed up) you can hear the cylinders slowly charge and eventually start. It can be a slow and frustrating process.

I was advised that the way to remedy this is to mount the fuel pump forward behind the tank to push the fuel rather then pull the fuel for quicker starts. Very little fuel drains back into the tank with this new configuration.

It would not appear to be difficult to perform, aside from fabricating a mount in the area of the pedal cluster or master brake cylinder. A new fuel hose would have to added and the fuse link identified. The fuel pump on the 1973.5T does NOT have a relay associated with the pump. I believe power is drawn from fuse 7 or 9.

I have to ask, if anyone has anyone performed this operation and just how successful it has been.

Thanks

Bob
73.5T

ossiblue 10-29-2018 07:54 AM

Quote:

Originally Posted by Sunroof (Post 10231479)
One of the quirks of the 1973.5T/CIS model is that the fuel pump in mounted in the rear wheel well and despite the claim that the pump has a check valve, every time you restart the car you have to draw the fuel back quite a ways to get it started. Listening to the engine when starting (without hand throttle and car warmed up) you can hear the cylinders slowly charge and eventually start. It can be a slow and frustrating process.

I was advised that the way to remedy this is to mount the fuel pump forward behind the tank to push the fuel rather then pull the fuel for quicker starts. Very little fuel drains back into the tank with this new configuration.

It would not appear to be difficult to perform, aside from fabricating a mount in the area of the pedal cluster or master brake cylinder. A new fuel hose would have to added and the fuse link identified. The fuel pump on the 1973.5T does NOT have a relay associated with the pump. I believe power is drawn from fuse 7 or 9.

I have to ask, if anyone has anyone performed this operation and just how successful it has been.

Thanks

Bob
73.5T

Yes, I had that change made on my 73.5T. Actually, it was done by a PO and I modified it a bit when a new pump was needed. Since there was no bracket on the front cross bar, one was fabricated along with some padding for vibration dampening, and new hoses to connect it all together. Nothing too difficult. I no longer have the car so I cannot give more detail except to say it was an improvement and was easier on the pump.

Ian Comerford 10-29-2018 08:01 AM

Would it be possible to fit it where it is mounted on slightly later cars such as SCs ie on the front cross member? You could then use existing parts.

Ian

Sunroof 10-29-2018 10:00 AM

Not sure where it would be mounted or shielded. but I suspect under the removable panel that protects the pedal cluster, brake master cylinder, etc. near the tank. This model (1975.5T) was the only one with this configuration for the CIS system. It was changed on the 1974 model going forward. Further, no relay is present for the fuel pump on this model. The 1973.5T is an interesting car (no fuel pump relay, no thermotime switch, hand throttle, no adjust WUR, etc).

targa44 10-29-2018 09:47 PM

So, right now, you have no circuit to shut off the fuel pump if you're in an accident and incapacitated?

joefrantz 10-29-2018 10:07 PM

Here are some past discussions on this topic:

http://forums.pelicanparts.com/porsche-911-technical-forum/902144-relocating-fuel-pump-up-front-steel-cross-member.html

75 911s 10-30-2018 04:35 AM

Quote:

Originally Posted by Sunroof (Post 10231717)
This model (1975.5T) was the only one with this configuration for the CIS system. It was changed on the 1974 model going forward. Further, no relay is present for the fuel pump on this model. The 1973.5T is an interesting car (no fuel pump relay, no thermotime switch, hand throttle, no adjust WUR, etc).

My 75 has this exact same setup. So at least 3 Model Years. Starting in 76 they are mounted in the front.

BoxsterGT 11-02-2018 01:05 PM

:)

I make up a front pump mount for the early cars.......

http://forums.pelicanparts.com/uploa...1541191953.jpg

This also has a Dansk Tank that I have supplied a Pre-Filter for to protect the new fuel pump.

For info, please email me. Len dot Cummings at verizon dot net

:)

fred cook 11-03-2018 06:04 AM

Easiest/possibly best way is to replicate the design used on the SC cars. As mentioned earlier, you can use all original parts. All you would have to do is drill a couple of holes in the rear side of the crossmember. And, it is shielded there by the front cover.

Harpo 12-14-2018 03:40 PM

How do you power the fuel pump now that it is located up front? I pulled my tank today and plan on getting new fuel lines from Len after the holidays

Thanks

David

BoxsterGT 06-21-2019 05:37 AM

:)

Early 911's have a tubular crossmember, so the SC mount will not work.

I am using rubber lined loop clamps and (2) metal angle brackets. The lower is supported by the crossmember and the upper by the steering rack.

It's a little offset to one side but the hoses still seem to fit nicely. The photo above gives you an idea of how it mounts, but I will post another as soon as I put one more together and paint it.

For info, please email me.

Len.Cummings at verizon.net

:)

GH85Carrera 06-21-2019 05:41 AM

Moving the pump to the front is a good idea.

My old 914 had the fuel pump in the engine compartment. The gasoline vapor point was changed, and I would get vapor lock while cruising down the highway at 55 MPH in the bad ol days of 55 MPH limit.

I moved it to the front and never had that issue again.

BoxsterGT 06-21-2019 09:28 AM

:)

Rec'd another inquiry, so here it is before paint......

http://forums.pelicanparts.com/uploa...1561138001.jpg

Got to keep these wonderful cars on the road for generations to come.

Len

:)


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