stv951

Just discovered that the second fuel pump on the GTS is not working. Would that affect performance ? When does it engage ?
Car is 5sp manual btw

Alan

In dual pump systems both pumps are controlled the same way - both on all the time when running - wired in parallel - & yes it will affect performance....

Alan

stv951

So they both get the same power all the time ? How much am I losing ?

Randy V

Well, you're probably 'gaining' bout 4 mpg.

Bill Ball

The internal pump becomes and impediment if it is not pumping, unless the rubber connector between it and the tank outlet is completely split, as often happens. Anecdotally I can say George Suennen's car would not accelerate much over 120 until we replaced his failed internal pump.

ROG100

On my GTS replacing the failed internal pump stopped the pinging.
I have it in stock for $139.95.

Louie928

The more serious problem is that the internal pump has it's connecting hose split. That lets dirt and bits of crumbled hose get to the inlet of your external pump. There is no filter in between. Your external pump will jam and stop. So will you, and it often picks a difficult location for you to be stranded. It's not fun. Replace that internal pump as soon as you can.

Charley B

What is a quick way to diagnose this problem?

Bill Ball

The hose split? You need to drain the tank and pull out the internal pump. I did it to my 89 when I had some top-end leaness on the dyno. Of course, the hose and pump were fine even at 150K miles. I replaced them anyway.

Charley B

You're right Bill, I wasn't thinking of the split hose, just the pump. Guess the only way to know is pull the whole thing out and inspect it.

Randy V

Is there a write-up out there that describes pulling/inspecting the in-tank pump?

Rob Edwards

Randy-

Here's one, there must be others.

https://rennlist.com/forums/showthre...ight=fuel+pump

ROG100

The internal fuel pump looks like it is going to be NLA as of now.
I have a few at the old price of $139.95 but once they go they are gone.
I just placed an order for some of the remaining ones in Germany with Porsche and the price will jump to $173. Get them while they last 8>)

What happens when we have no more pumps - put a strainer in there and go to the 044 pump????

pmooradian

The hose split on the internal pump on my GTS, so even though it was running, it was pumping most of the fuel out the split in the hose. My GTS will ping on a good day with 91 octane fuel, but it was really bad when the internal pump wasn't working. Although I replaced it with a new one, it isn't that hard to just replace the hose if the pump itself still works and all that's wrong is that the hose has deteriorated.

Looks like we might have to get creative if they're going to be NLA. I would guess a higher output main pump and a screen to replace the internal pump would work.

pmotts

Andrew has a nice write up on the procedure of changing to the 044 pump and tank screen. The one thing I would add to Andrews write up is the hose is different when you change to the tank screen from the in tank pump. Even if you don't change the wiring (highly recommended) the positive connector won't fit over the positive post of the 044 pump.
Jim



https://rennlist.com/forums/928-forum/378533-how-to-replace-your-fuel-pumps-including-how-to-install-an-044-pump.html