Quantum Pump Questions

M

marc2000gt

Active member
So I purchased the Quantum pump and canister setups and the fuel pressure dropped in the rear tank after a short period of time. I found the threads on here about them leaving out the spacer at the top of the pump so I am sure that is my problem. My question is will I have the same issue on the front pump or is it not an issue since the canister is different? I don't have my old units anymore to see if the front pump has the spacer.
 
Mine was the rear. Never changed the front to quantum so would not know. I would expect the same issue though.


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So I pulled the rear pump and have the same issued you all have mentioned. I do not have the stock setups anymore. I do hav3 some quad seals, do you think I can used them instead of the stock piece that is missing?
 
marc2000gt said:
So I pulled the rear pump and have the same issued you all have mentioned. I do not have the stock setups anymore. I do hav3 some quad seals, do you think I can used them instead of the stock piece that is missing?
Click to expand...
Have you called and asked Quantum to send a replacement? Maybe you have the older version. I purchased one from them in April and it was a different design with some improvements. I took it apart to get reference pictures after reading about the issues. 1704161335250.jpeg
 
My Quantum pumps did the same thing, multiple times. What I found is that the new pump drops down inside the canister. When that happens, it eventually pushes the grommet down enough to where it causes fuel to leak back into the canister, thus causing the pressure to drop. I took the grommet out of my old canister, sliced it to about half its thickness, and put it under the grommet on the new pump...basically increasing the total thickness. I haven't had any more fuel pressure problems since then, from either tank.
 
Required said:
Have you called and asked Quantum to send a replacement? Maybe you have the older version. I purchased one from them in April and it was a different design with some improvements. I took it apart to get reference pictures after reading about the issues. View attachment 104722
Click to expand...
I have not asked about a replacement. I had them at least a year before installing them.
 
Blurry94 said:
My Quantum pumps did the same thing, multiple times. What I found is that the new pump drops down inside the canister. When that happens, it eventually pushes the grommet down enough to where it causes fuel to leak back into the canister, thus causing the pressure to drop. I took the grommet out of my old canister, sliced it to about half its thickness, and put it under the grommet on the new pump...basically increasing the total thickness. I haven't had any more fuel pressure problems since then, from either tank.
Click to expand...
I found the same thing, the pump had pushed down. When I first installed it, I had good fuel pressure, then noticed that my pressure dropped. Just trying to give it a quick rev in park will make my fuel pressure drop now. The other issue is that when I pulled the pump apart, the plastic tube with the oring came out with it. So it looks like I will need a new canister.
 
It looks like they're attempting to remedy the problem with that. As long as it covers the barb on the pump, nearly to the top, then it'll fix the pressure loss issues that many have had with these units over many years.

I did find a pic of when I modified mine back years ago to fix this issue. I used a full grommet and cut another one in half and stacked them...no issues thus far.

Pump Mod.jpg
 
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