Diagnosing Fuel Leak - Help Please

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Hersir
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Joined: Fri Jul 24, 2009 12:41 am
Location: Virginia

Diagnosing Fuel Leak - Help Please

Post by Hersir »

I'm hoping the power of the Pinzgauer hive mind can help me diagnose a fuel leak.

Yesterday I was driving my 710M and noticed a strong smell of gas. When I parked, I saw a steady drip of gas coming off the undercarriage close to the center tube across from the fuel tank. There was no leaking before I started driving and it stopped about 10 minutes after I parked. The filler tube area looks dry which made me think that it might be a sending unit seal, or possibly the fuel pump. The truck seemed to run fine at idle and at speed. I am not a mechanic but like to do the work I can do with basic tools. I'm trying to figure out if this is something I can fix with some new seals without dropping the tank or if I need to take it in to a shop.

Thanks all.
1975 710M (Swiss)
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rmel
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Re: Diagnosing Fuel Leak - Help Please

Post by rmel »

Given the amount of fuel you are leaking you should be abler to spot the problem.

I'd remove the seats and Dog house, air filter and air intake manifold on top of the carbs.
This will expose most of the areas of interest. Then just get down to some basic inspection.

Attempt to try to identify any wet fuel spots with the engine OFF. Look around the base
and tops of the carbs, sides, hoses and fittings. It could be anything from a bad fuel line
to the carburetor bowls overfilling, or a fuel pump leak. Given the amount of fuel you seem
to be leaking you will probably spot the problem pretty quickly.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712MK

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Hersir
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Joined: Fri Jul 24, 2009 12:41 am
Location: Virginia

Re: Diagnosing Fuel Leak - Help Please

Post by Hersir »

Thank you, I did just that and it became pretty clear that it was the brass outlet from the fuel pump. It wiggled in and out easily and when I turned over the engine it starting leaking from that connection immediately. I cleaned the brass fitting, sanded the exterior lightly, and used JB Weld to glue it back in place. We'll see if this does the trick. Worst case, I'll be replacing a fuel pump. Thanks again.
1975 710M (Swiss)
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pcolette
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Re: Diagnosing Fuel Leak - Help Please

Post by pcolette »

Your method of repair should work just fine. I've done that a few times myself.
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Paul C.
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'73 Swiss 710M
'89 Puch 230GE
ChickenPinz
United States of America
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Re: Diagnosing Fuel Leak - Help Please

Post by ChickenPinz »

Hersir wrote: Sun Jun 06, 2021 12:45 pm Thank you, I did just that and it became pretty clear that it was the brass outlet from the fuel pump. It wiggled in and out easily and when I turned over the engine it starting leaking from that connection immediately. I cleaned the brass fitting, sanded the exterior lightly, and used JB Weld to glue it back in place. We'll see if this does the trick. Worst case, I'll be replacing a fuel pump. Thanks again.
if the epoxy repair doesn't work, then you can get just the top section of the fuel pump as a replacement part. As a bonus, that section includes the two flapper valves that get tired over time and cause a vehicle to be hard to start after sitting for a few weeks. Change that part and she'll start right up even after several weeks of sitting idle.

Others have reported the epoxy fix works pretty well, and yours is certainly not the first to develop a leak at that insert location.
710K
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