PorscheBubba

1981 928 will start but not stay running.
1. Is 82 same as 81 because I have manual for 82.
2. Car start but does not stay running.
3. I can hear fuel pump in tank run when switch turned on but pump never stops even after 30 seconds so is that normal? (Car not running)
4. Should car have 1 or 2 fuel pumps?
I looked around but could not find my sprcific problem. Thanks

GlenL

Sounds like you're starting up the ladder of 928 learning.

1) As always it "depends." There are many models of this car. Full info always helps. An US '82 is just like an '81 US car...unless it's not, but mostly it is. Same for Euro or "Rest of World" cars.

2) This is going to take some more info and analysis

3) Not right. The pump should come on for a moment and then wait for the engine to start cranking. Seems there's something wrong and a likely culprit is someone has replaced the correct relay with the wrong relay.

4) Yes. 1 or 2. Most cars will have just 1. This varies by year and market. You can look under the tank to see if there are wires running into the tank next to the outlet hose on the bottom.

Welcome. Do you have the PET and manuals? Both are available on the internets for free download.

PorscheBubba

Can you poin me in the direction of figuring out if the wrong relay is causing my fuel pump problem? I have not downloaded any manuals yet. Thanks

GlenL

Manuals:
http://www.ligeti.com/928/

Fuse/relay charts:
http://www.928gt.com/t-81fuse.aspx

Open the panel in the passenger's footwell and take a look at what's in there.

PorscheBubba

I have been looking in pannel in passenger side footwell but didnt know a relay could fail causing the fuel pump to Never cut off. I am decent with mechanical but electrical is not my thing (which is what fails on 928 from my reading). If I can get car to stay running this site has enough maintance information to keep car on the road. Thanks

PorscheBubba

1. Any idea what gray cable is?
2. Green is O2 sensor whic is not connected
3. Think you are correct about wrong relay-will replace

Thanks for the help and if you perfer a supplier for replacement parts please let me know who so I can support them.

GlenL

Well, that's not pretty. The gray cable is aftermarket. Power for audio stuff?

I mostly use 928 International, Pelican and Vertex for parts.

PorscheBubba

I thought aftermarket but never hurts to ask. I will look around for contact for the suppliers mentioned. Thanks

PorscheBubba

Vertex lists an aftermarket fuel pump relay, do you recommend that or should I find a OEM? Thanks

PorscheBubba

1. I ordered fuel pump relay because wrong one was installed
2. I ordered fuel injection relay because old was rusted/corrison

I feel conifident that I jumpered fuel pump relay properly. Then I jumpered fuel injection relay with 3 way jumper from pin 30 to both 87 pins which all 3 pins are horizional from left to right. (Hope that makes sense). Now car runs for 2-3 seconds then dies. What suggestions can someone offer me? Thanks

Mrmerlin

I would suggest to wait for the correct relays.
jumping systems without full working knowledge can cause Lucas smoke to exit the wires.

So while your waiting you deoxit 100 the fuses and relays on the CE panel,
and clean the grounds and battery terminals
note there is a ground or two on the right cam tower make sure they are clean.

GlenL

You'll find the parts market to be difficult for these cars. Parts may have Porsche, OEM, good aftermarket and cheap aftermarket variants but that one part may not come in those flavors. Authentic Porsche parts can be ludicrously priced driving a guy to pick something else. I get the part that feels right for price and brand.

I didn't look into this part but some relays have only expensive Porsche and cheap knock-off offerings. You make get what you pay for.

Sounds like you're on your way. It sounds like a FI system problem to me.

PorscheBubba

Parts are to arrive 8-3-16 from pelican (I really like them so far) vertex tech support was VERY rude in my opinion. Green wire looks new but was not installed by me so not sure of its condition. When looking at ignition diagrams they are hard for me to understand. If anyone can suggest order of power it would be nice to have so after relay install I can trace if needed. I am going to look to see if it has L Injection which it should because its a US Car. I welcome other advice to look over while waiting on parts. Thanks

PorscheBubba

1. I think since car is L Jet sice its a 81 US Car but can someone tell me how to verify?
2. Green wire looks good to me what is your opinion?

GlenL

The green wire looks like it's newer. Check that it doesn't run in contact with the block. The FI system looks like an L-jet. In 1981, the other option for FI in the 928 was CIS for Euro (RoW) cars.