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the inlet tube on my 710 fuel pump is loose and wobbly in the hole and leaking gas from there. is that something i can fix, or do i need to order a new top piece? i haven't removed it to see if it's just a pressure fit or how it's inserted, just trying to get ahead of this repair.

The inlet and outlet tubes are press fit and over time have been known to come loose. I learned from Thilo Kass to use JB Weld Kwik to secure them in place after a thorough cleaning and mild wire brushing. Use a toothpick or similar item to pick up a dollop of JB and spread it around the seam.

Alternately you could replace the top half of the pump which would give you 2 new internal one-way valves also. https://swissarmyvehicles.com/pinzgauer ... -fuel-pump

If your truck takes a long time (>15s) to start after sitting for a couple weeks, then I'd replace the top section of the pump so as to get new valves.

If your truck starts okay (<6s) after sitting a couple weeks, I'd follow that excellent JB Weld advice.

My truck had starting issues after being parked for a couple of days.
I replaced the mechanical fuel pump with an electric one. My choice was Hardi 18824.
Now I hear the pump delivering fuel to the carburators and once the bowls are full, the sound stops and the truck starts on first attempt.
The mountig hole for the mechanical pump was clesed with a piece of 5mm sheet metal, cut with the gasket as template.

Albert,

I too went with Hardi however with P/N # 14424 which is set at ~0.22 bar e.g. 3 psi.
That used to be listed on the Prokschi web site but now I see the 18824 listed which
is closer to 5 psi pressure average. No issues so far at temp or elevation. I believe
at one point in time S-Tec also was using the 14424 for upgrades. Any idea why the
P/N change? Perhaps availability or a either/or situation ??

Incidentally, these were available on Amazon.co.uk 2 years ago -- no longer available.

rmel

I decided to switch to an electric pump last winter, when my Pinz was parked for several weeks and I had to crank for some time to start it.
Hardi has a webshop, where I followed the specs and selected the 14424.. The pump was delivered within a few days and immediately installed. Now I just have to listen to the rattling sound of the pump to cease, kick the accelerator twice and the truck starts immediately.
A few weeks later I was asked to tow a 710 on a trailer for a mate.Towing on the flat motorway was no issue, but as soon as we reached an ascend the pump started rattling audibly, the engine lost power and we had to stop..
At the third involuntary stop I reverted to the mechanical pump, and we finished the trip without further delay.
The following Monday I contacted Hardi support, and the pump was swapped for a 18824 model free of charge.
I tested towing another heavy trailer uphill, and the pump worked flawlessly..
A few days later I visited Matthias Prokschi to purchase new gaskets to cover the opening for the mechanical pump. We chatted bout my experience with Hardi, and that made him change the model recommendation on his website.

Very interesting. Hmmm, I do recall one point I forgot to make -- HEAT.

Initially, I mounted the Hardi in the area of the mechanical pump.
One warm day I noticed that the pump was activating a bit more than
it was when cold at the same RPM. I measured the temperature in the
general area and came to the conclusion it was a wee bit too close to
the max spec of the pump. I then relocated the pump in a lower and
cooler position behind the Jerry can -- problem went away, less siphoning,
and lower temp. So....I wonder where you mounted your pump and if the
heavy load you were pulling just got the temp a tad too high reducing the
efficiency of the pump?

I also helped a friend install the same Hardi 14424 in the same lower
position on his 710 and so far runs well.

Are those pumps nicely sealed against water/dust/dirt ingress so it's not a concern to mount them more in the Gunk Zone?

rmel
I don't think heat was the reason; there was snow outside ...
I mounted my pump underneath the air filter support strut in a horizontal position.
Unfortunately I did not take pics.

ChickenPinz
Yes, the pump is fully sealed against dust and water.

Ah yes. I am familiar with that mounting location near the air filter.

I had a high pressure Pierburg pump located there for my 710 EFI.
Had to move it lower due to siphoning challenges with an impeller
based pump -- would vapor lock on occasion.

Of course the Hardi would not have that problem but I got squeamish
locating anything there due to prior experience. But I agree, it's a
good choice for this class of pump.

I mounted the PinzFDS right on top of the engine. I have had this for 7 years without any temperature related problems. The pressure is set at 3.25 PSI.