Fuel leak. Need to pick some brains.

Aintezbeincheesy · Post by **Aintezbeincheesy** » 26 Aug 2017, 15:43

Hey all. Got a 94 volvo 850T, 130k miles here. Started noticing a small puddle of fuel developing under the fuel tank by the rear passenger tire. I removed the fuel pump cover in the trunk to try and get an eye on the vent hose that keeps coming up when I research why this is happening. When I removed the cover the fuel pump had a pool of fuel sitting around it. I'm sure if the vent hose was cracked it would pool fuel around the pump. Just wondering at the chances of a bad fuel pump? I just filled the tank so it will be another couple of weeks before ill be able to drop it.

Post by **abscate** » 26 Aug 2017, 15:47

Probably a bad gasket around the fuel pump hole. This should be sorted out before driving again. Fuel leaks are dangerous.

Post by **kahl** » 26 Aug 2017, 16:13

On my 94 850 I had to replace the fuel tank vent hose. It is located on the top of the tank. Dropped tank to replace. Part number is 3501350.

Aintezbeincheesy · Post by **Aintezbeincheesy** » 26 Aug 2017, 17:11

Forgive me if this is a dumb question, but I can replace just the gasket, right?

Post by **tryingbe** » 26 Aug 2017, 17:46

Remove the fuel pump bypass plate and see where the fuel is coming from.

Aintezbeincheesy · Post by **Aintezbeincheesy** » 26 Aug 2017, 18:02

tryingbe wrote: ↑26 Aug 2017, 17:46 Remove the fuel pump bypass plate and see where the fuel is coming from.

If that's the plate over the fuel pump in the trunk I can't really get eyes on anything other than the fuel pump itself. I'm considering picking up a borescope for my phone expressly to be able to see what's going on there.

PeteB · Post by **PeteB** » 27 Aug 2017, 08:22

Be sure to understand how to remove the fuel line connections at the fuel
pump, they will break if not done right.
I would siphon 2-3 gal out so that you can drive it, use it and have it safer
to work on.
Check if you have the short/long hose and change it first. Our hose was
wet when it leaked, no need for a borescope.
I also did the filler around the wires going into the fuel pump, did not
do the gasket.

Post by **erikv11** » 27 Aug 2017, 11:51

Check it out before you order any hoses. The vent hose definitely fails a lot but the gaskets fail far more frequently. Yes, you can replace just the rubber gasket. Buy the Volvo branded one. Not a bad first guess "throw a part at it" move, if you don't have a lot of time to troubleshoot right now. But abscate's point is important sure, don't keep it topped off if it is leaking.

Post by **jimmy57** » 27 Aug 2017, 11:59

Does it only leak when filled or leak until it gets down to some level?
Sender/pump seal is a full tank leak. SOme hoses can leak due to syphoning effect but will leak until it gets to 1/4 tank.
If it only leaks when runiing and quits when engine is off then it is fuel supply line leak.
Then there is the recall for heat shield attachment points on tank breaking that affects some 850's.

Post by **tryingbe** » 27 Aug 2017, 12:50

Aintezbeincheesy wrote: ↑26 Aug 2017, 18:02
tryingbe wrote: ↑26 Aug 2017, 17:46 Remove the fuel pump bypass plate and see where the fuel is coming from.
If that's the plate over the fuel pump in the trunk I can't really get eyes on anything other than the fuel pump itself. I'm considering picking up a borescope for my phone expressly to be able to see what's going on there.

Did you take the plate off and found nothing leaking/wet?