Fuel pump question

Hello there. I'm brand new to the 928 family and have loved Porsche for as long as I can remember. That being said, I have zero experience with Porsche and the 928. I have only worked on VW bugs. This 928 seems quite a few notches above working on a bug. Anyway, It's a 1979, and has no service history. It's been off the road for 3 or 4 years the previous owner thinks. He got it from someone in his neighborhood but hasn't done anything with it. He's removed the fuel tank, cleaned it out but that's about it. I see that new in tank fuel pumps are pretty pricey. Are there any alternatives that people have used with success or should I plan for $600 - $800 for the in tank pump? I'm sure I'll be posting a few things. I'm looking forward to trying to get this car up and running again. When I get the car I'll post a picture.

Hi and welcome! I went through the same thinking process with my '79. Let me tell you what my strategy is./was. After talking to Roger at 928sRUs, I replaced the external fuel pump and put a filter in the tank instead of the internal pump. It was enough to get the car running so that I could keep working on it. I figured that I could always add the internal pump if I really need it. Roger says that this is a pretty standard approach with these older models.

Thanks for the reply. I'm interested in learning why the 2 pump setup was used in the first place. Obviously it's there for a reason. But if I can at least get the fuel moving using just the external pump for now then I might try that option first to at least see what's up with the engine. There's going to be a lot of research for sure. I'll know more when I pickup the car on Saturday and hope all the parts the previous owner took apart are still around. Thankfully it looks like he didn't do too much dismantling.

We don't know the decision making process for Porsche. The 1978 - 1979 CIS cars had two Fuel pumps. Later, some cars had two, some didn't. My 1993 GTS has two fuel pumps. There are theories that for hot climates the in-tank pump helps reduce the chances of vapor lock ... we don't know.

Rich928 wrote: We don't know the decision making process for Porsche. The 1978 - 1979 CIS cars had two Fuel pumps. Later, some cars had two, some didn't. My 1993 GTS has two fuel pumps. There are theories that for hot climates the in-tank pump helps reduce the chances of vapor lock ... we don't know.

That's my understanding as well. Everything that I've read hints that the two pumps are to avoid vapor lock when running hard in hot locations.
I'm going to dig into my CIS this summer. One of the tests is the fuel flow rate with one or two pumps. I'll be sure to report what I find.

Being in Washington state we at least don't get the heat very often up here. I'll probably lean towards the single pump set up for now unless I come across a reasonable priced option for in the tank. Just picked up the car on Saturday and haven't had a chance to start going at it.