You can't tell because even a defective pump will work most of the time at first. Fuel pumps wear out, it is a wear item amd not a good choice for used. With that said, I got lucky and found one that obviously had just been installed and was a brand name. I took the hoses too and have had no trouble, a year later. They also sell cheap fuel pumps on eBay which are very complete as to hardware, while the quality pumps cost over $100 and do not include anything. I would not trust one of these cheap kits. The junkyard garantee will most likely be only for credit. If it is a used original fuel pump it is clearly not worth it. Plus, it might very likely have been driven low.
I would be concerned about how old the vehicle is. I watched one guy get 3 used fuel pumps before finding one that worked for a 20 year old van. IMHO it would be better to just get a good new one to save on labor and peace of mind.
With something like a fuel pump which can leave you stranded if it fails, you are better off buying a brand new one. A used one could go out again soon. It's a gamble.
Is the fuel pump in an area where you can cut an access hole through the trunk and get to it? A friend of mine drove a cargo van over the road, so the hole was in the cargo area covered with sheet metal, he carried a spare pump with him, it only took him 15min to change it and get back on the road
Make sure you get a written 30 day warranty and install it as soon as possible.One last important word of advice.There is a "sock" on the inlet portion of the pump.That is it's filter.MAKE SURE YOU REPLACE IT!!! Most places will not back the warranty if you don't.
There is no complete way of knowing unless if the junkyard car has gas in it and you can do a fuel pressure test. The video will show you how to do a complete fuel pressure test. A pressure gauge is only $20 and well worth the money.
Many cars have an access hatch, under the back seat, for easier fuel pump removal.
Recommends buying a new pump unless the donor vehicle has really low miles
You can test it. You can measure the resistance, current and look at the voltage variations when it is running. You can measure the static pressure that it creates and the volume that it produces under pressure.
The fuel pump in one of my cars went bad, so I went to the junkyard to get a replacement for $40. There is a 30 day return policy if you're unsatisfied with the purchase, so I'm not worried about wasting, I'm worried about wasting all the time and stress lowering the fuel tank and replacing the pump only to find out it isn't good either. How can you tell if the pump is working?
If the car runs
*not worried about wasting money"
Then buy a NEW one cheapo. SHEESH.
