fuel pump inop.

ice-hot · ice-hot's Garage

Has anyone run there 78-79 m.y. with only the external fuel pump?
Will it run with just the external pump operating?
As you have probably guessed mine quit, and I cant find one available in my area.
The car will idle but kills at throttle, is this pump the problem? Looks like it has not operated in a long time.
Does anyone know where I can get it?
Thanks,
John

Mrmerlin · 09-12-2009, 03:14 PM

IIRC you have 2 external pumps one in the rear of the RR wheel well and one at the tank, what pump isnt working??
Have you tried to run the non working pump backwards?? by reversing the wires??
If you have a stuck pump remove it then spray some carb cleaner into the inlet and let it sitr over night then see if it will spin if it runs then fill a small container with Marvel Mystery oil and circulate the fluid through the pump, dont run the pump dry

ice-hot · ice-hot's Garage

Hi Stan,
Thanks for the reply.
"78"-"79" US have a fuel accumulator and filter in the wheel well. The pumps are at the tank.
One screwed in the bottom of tank and one inline just out of tank. The in-tank one is inop.
I got it running again but its intermittent and 30 years old so I'll look for new.
I thought I had read that some had run there cars on one pump.
What I was wondering is if anyone has run there car with just the in-line pump?
Thanks again,
John

MPDANO, didn't you have a reasonably priced source?

american-kiwi · american-kiwi's Garage

look up into the rear of the wheel well...the 2nd pump is right by the taillight area, MPDano said he got his to run on one pump...mine wouldnt...i needed the 2 pumps 78us

Mrmerlin · 09-12-2009, 04:06 PM

if you have an internal pump then you will also have a set of wires going to the fuel outlet of the tank, is this so??

ice-hot · ice-hot's Garage

Hey John,
Thanks. How is work going on your "82"?
This is a "79" US and I have found both pumps. The external is under a plate, on the bottom rear of the tank. Apparently they made a location change around 11/78 production, can't remember the serial break.
You answered my question though. You had to have both pumps for car to run.
Was this on your "78" or "82"? Did it run at all, would it idle with one pump, or nothing?
Thanks again,
John

ice-hot · ice-hot's Garage

Quote:

Originally Posted by Mrmerlin

if you have an internal pump then you will also have a set of wires going to the fuel outlet of the tank, is this so??

Yes, it does. I have the pump out, but its shot. Runs, but upon disassembly found the magnets in the motor were crumbling.
Something I've never seen happen.
Maybe something to do with gas dissolving the glue that held them to the housing and the armature chipped them when rotating?
Anyway its bad and I am looking for a replacement.
Anyone know a reasonable $ source?
Thanks,
John

Mrmerlin · 09-12-2009, 07:13 PM

There are plenty of vendors just make a few calls and see who has the best price and service, I would go with Roger

ROG100 · 09-13-2009, 07:03 AM

The internal pump is becoming extinct and only available from Porsche.
Never tried running on one pump. Due to the higher pressures needed for CIS cars we may need to find a higher capacity pump to replace the existing two - maybe. I guess we will worry about that when the supply stops.
Internal Pump 928 608 013 00 and $206.

MPDano · MPDano's Garage

My 81 Euro is CIS and have been running with a single pump for almost a year now (gutted internal fuel tank pump). I try and drive my car at least twice a week to work (about 50 miles round trip). I have no problems at all.

Not sure if this is related, but when I take a right turn very quickly (wannabee Grand Prix Driver), it does seem to lean out a second (pinging). No issues if I make right turns as a normal human being though.

ROG100 · 09-13-2009, 08:44 AM

There are 6 external pump variations. Not including the 44 high output pump or the internal pump.
On the ROW 80 to 83 300HP they use a single pump 911 608 102 02.
This pump should be ideal for the early cars and negate the use of the secondary external or internal pump.
Just a thought.

On the subject of pumps a number of my customers have replaced the single external pump for the US 80 to 86 cars (928 608 104 01) with the pump used on the 87 to 88 S4. Fits without issue and works. Reason COST one is $235 and the other $160.

ice-hot · ice-hot's Garage

Thanks MPDano and ROG101,
So it seems that the "78"-"79" US m.y. need two pumps or the one higher psi pump ROG101 has referenced.
This info. helps, thanks allot.
John

MPDano · MPDano's Garage

I pretty much go with whatever a 78-79 uses for my 81 Euro. 81 US is EFI and this is why it became a nightmare for me during Smog Tests.

MPDano · MPDano's Garage

Heres a link to where I bought my pump. You can see the CIS Pumps have that longer neck on them.

http://www.***************/search/product.aspx?sid=cs4tfy550usnpzq1fbputy55&makeid=800019@Porsche&modelid=1263349@928%20&year=1979&cid=22@Fuel%20%26%20Air%20System&gid=6256@Fuel%20Pump,%20Electric

Part # 69513 is what I have in my car now.

[IMG]http://www.***************/secure/PartImages/69513.jpg[/IMG]

This is the internal one that I ended up gutting, basically a tube now.

[IMG]http://www.***************/secure/PartImages/92860801300.jpg[/IMG]

ROG100 · 09-13-2009, 11:56 AM

MPDano,
I think you missunderstood.
The pump used in the 78 & 79 as the primary external is not man enough on its own in all situations. Needs a secondary pump either internal or external.
Thats why I suggested the external pump from the 80 through 83 CIS ROW cars.
Roger

ROG100 · 12:15 PM

MPDano,
69513 is 911 608 102 00 is the early CIS pump that needs a seconday pump to make it work - maybe thats why you are having some leaning out issues.
Roger

MPDano · MPDano's Garage

Quote:

Originally Posted by ROG100

MPDano,
69513 is 911 608 102 00 is the early CIS pump that needs a seconday pump to make it work - maybe thats why you are having some leaning out issues.
Roger

True, true Rog. For now, I just won't drive like and Indy Car Driver and I'm Golden with my single pump. Someday, when the economy comes in my favor, I see an in-tank pump coming into play.

ROG100 · 09-13-2009, 07:04 PM

MPDano,
Fully understand and with that expectation your car and the pump will be fine.
Roger

DPW928 · DPW928's Garage

Some of the early CIS 928 came with one pump and some came with two. The decision of one or two was based upon the destination climate. Hot climates got two to preclude vapor locking during prolonged idle like stop and go traffic. As a minimum the 928 CIS sytem needs 5.5 bar pressure to operate properly. An aftermarket 6.5 bar Pierberg/Pierburg pump can be purchased for around $200 which should fill an CIS fuel requirements.