Fuel pump malfunction ('70 280 SL)

[Ferrolanoman]

Last week I filled up with ethanol free gas, came home and upon parking I found a serious fuel leak coming from my fairly recent replacement (expensive!) M-B fuel pump. I drained the tank of 10 gallons, tested it and the car started and ran normally, but it continued leaking so I emptied the gas tank completely. Unwilling to spend $$$ on another M-B pump I fitted the recommended Carter 4601 HP generic replacement, connecting all the hoses correctly I hope (including the by-pass T of the return line) and added approximately 5 gallons of gas. The car started normally and ran for a few minutes in my garage, no leaks anywhere. Next day, I wanted to make sure all was OK with the new pump so I put in more fuel (4-5 gals) prepared to go for a test drive. The car started it with some hesitation, missing a bit which I attributed to the expected brief warm-up period BUT then shortly quit running and would not restart. The Carter pump had stopped working, its bowl noticeably warm to the touch. It was dead.
I removed it and plan to return it to Amazon, hopefully they'll issue a refund but I have no way of knowing whether it was a faulty pump or something I did wrong.
I'm puzzled and wonder if filling or possibly OVER-filling my gas tank is directly related to the M-B pump leaking so much and the Carter failing completely so suddenly. Can someone here lend an opinion as to what may be causing these two failures (I don't believe in coincidences) and what I can do to solve this issue? Did I cause some obstruction that remains, something dislodged by the force of so much fuel pumped in? Did I install the fuel hoses correctly?
Thank you in advance for any and all comments.
Ricardo

[mdsalemi]

Where exactly, on the Bosch (MB) pump, was the leaking?

Have you gone through the entire fuel system? Starting at the tank (and screen/filter there); down to fuel pump; the lines there; then the soft line connection to the hard line, then the hard lines to the FIP, then the return line to the tank and ensure you don't have any, shall we say, "lack of integrity"?

You had indicated a leak from the Bosch, but a total failure of the Carter; these are different failures.

[Ferrolanoman]

The leaks were from behind the plastic cover where the 2 wires exit the mid-body of pump and also from the joint between the bottom plate/cover and the body of the pump. I interpreted this as a sign that the fuel was being forced out of the pump because it was finding an obstruction (loosened by the overfilling [?]) downstream.
What does FIP mean?

[mdsalemi]

FIP = fuel injection pump. In the engine bay.

[Ferrolanoman]

I feel strongly that the failure of both pumps (leakage of Bosch, meltdown of Carter) is due to an obstruction downstream, somewhere between the pump and its delivery point, but WHERE should I look? Its first stop which (I'm guessing here) is the large fuel filter canister in the engine bay, FIP, the fuel return line or some other location such as the fuel vapor tank and its pressure relief valve?
For testing purposes only, not long term, can I make a temporary simple/direct connection between the fuel pump and the FIP leaving disconnected all of the ancillary/auxiliary subsystems to get the engine running and subsequently, tracing one by one, reconnect them until the trouble is discovered? As I mentioned above, the car will run even when the Bosch/M-B pump is leaking.
I'm stumped. And I do not want to risk installing a third pump without ensuring that the system itself is not the cause, rather than trusting that the first one (Bosch) was going bad anyway and the second one (Carter) was defective right out of the box because it was made in China. Can all of this have really been caused by filling the tank to near its maximum??
Any and all ideas and suggestions are very welcome.
Ricardo

[BaronYoungman]

So I have never taken apart a carter pump but just in theory if the gas is not flowing ( the new cool gas coming though) and the armature still spinning trying to push the gas out, then the stagnant gas will become warmer and warmer eventually causing the armature ( or whatever Carter has spinning inside) to melt and stop. As for the bosch pump if the pressure build too much it will cause the gaskets to fail, in my option the one most likely to go 1st would be the one around the electrical connector, then the bottom plate would be the next most susceptible.  Hope that helps if I can be of more assistance 630 903 9877 Bob

[Ferrolanoman]

Bob,
Thanks for your reply. I can't say what caused the failure of the Carter, though it was warm to the touch after just a few minutes running--less than ten minutes. And, yes, the leaking of the Bosch is just where you indicated, though it continued to function allowing the engine to keep running.  But what caused these failures is the conundrum. Could it really truly have been a (very rare) coincidence unrelated to the full tank of gas?
If you or one of the experts on this Forum could draw me a basic picture of the complete fuel hoses loop that would help me immensely, for example:
1) where does the fat fuel hose go all the way when it leaves the pump? Where does it terminate?
2) where does the thin fuel hose from the tank go? Does it go to the small, drilled boss (mine is drilled and threaded) at the bottom of the Bosch pump or does it by-pass this pump orifice and go to the T junction?
3) What three hoses meet at the T junction?
Again, my thanks to all who can help solve the problem and get my SL back on the road.
Ricardo