Right fuel transfer not working
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Intermediate
Joined: Jun 2019
Posts: 26
Likes: 4
From: illinois
Right fuel tank transfer not working
Hello everyone!
tldr: my right tank is always full, the siphon jet pump is not clogged, there is pressure in the input line to the jet pump, but still the transfer is not ocurring. Can the return line be clogged? I see in pictures that the return line goes into the fuel pump basket, can there be positive pressure there preventing the siphoning to work?
Long story:
A year or so ago I started getting the PCM errors for the right sending unit. The car would drop the fuel gage to 0 and warn me, but I could still drive even below the half tank mark (could see after resetting the coses)
So the computer was detecting that the right tank had more fuel than the left tank, but I guess the difference wasn’t that big (ie some transferring was occurring).
But at some point that trick stopped working as I ran out of gas in the highway with half a tank of gas (right tank full, left tank empty).
Last weekend I finally attacked the problem, I emptied the right fuel tank (it had 30ish liters, so basically full), removed the sending unit assembly. Removed the jet pump, it was pristine, no trash, no build up, nothing. I still cleaned it. I guessed there was some rubbish in the line that got out when I was moving the assembly and emptying the fuel lines.
Before installing it I checked that there was pressure going to the jet pump by turning the key so the pump starts. There was a nice flow of fuel (not very scientific, but it seemed healthy, I will add a video)
I reassembled everything. Filled up the tank, cleared codes. And went for a long ride. But the error came up again.
So now I’m thinking that the issue could be:
1 - return line is obstructed preventing the siphoning to ocurr.
2 - there is positive pressure in the fuel pump basket (where the return pipes goes into) preventing the siphoning to occur.
3 - fuel pressure is low, preventing the priming of the line so that siphoning ocurrs
4 - charcoal canister problem generating positive pressure in the fuel tanks entirely? Seems unlikely as the tanks are both connected on the top so the pressure would be the same in all the system, and I don’t feel anything weird when opening the gas cap.
The mind boggles
Next steps I’ll take is empty and check the left tank next, to find any blockage in the lines or a problem in the basket. Also I could measure the flow going to the jet pump.
Does someone have any tips? Maybe something im missing?
thanks in advance!
Chris
tldr: my right tank is always full, the siphon jet pump is not clogged, there is pressure in the input line to the jet pump, but still the transfer is not ocurring. Can the return line be clogged? I see in pictures that the return line goes into the fuel pump basket, can there be positive pressure there preventing the siphoning to work?
Long story:
A year or so ago I started getting the PCM errors for the right sending unit. The car would drop the fuel gage to 0 and warn me, but I could still drive even below the half tank mark (could see after resetting the coses)
So the computer was detecting that the right tank had more fuel than the left tank, but I guess the difference wasn’t that big (ie some transferring was occurring).
But at some point that trick stopped working as I ran out of gas in the highway with half a tank of gas (right tank full, left tank empty).
Last weekend I finally attacked the problem, I emptied the right fuel tank (it had 30ish liters, so basically full), removed the sending unit assembly. Removed the jet pump, it was pristine, no trash, no build up, nothing. I still cleaned it. I guessed there was some rubbish in the line that got out when I was moving the assembly and emptying the fuel lines.
Before installing it I checked that there was pressure going to the jet pump by turning the key so the pump starts. There was a nice flow of fuel (not very scientific, but it seemed healthy, I will add a video)
I reassembled everything. Filled up the tank, cleared codes. And went for a long ride. But the error came up again.
So now I’m thinking that the issue could be:
1 - return line is obstructed preventing the siphoning to ocurr.
2 - there is positive pressure in the fuel pump basket (where the return pipes goes into) preventing the siphoning to occur.
3 - fuel pressure is low, preventing the priming of the line so that siphoning ocurrs
4 - charcoal canister problem generating positive pressure in the fuel tanks entirely? Seems unlikely as the tanks are both connected on the top so the pressure would be the same in all the system, and I don’t feel anything weird when opening the gas cap.
The mind boggles
Next steps I’ll take is empty and check the left tank next, to find any blockage in the lines or a problem in the basket. Also I could measure the flow going to the jet pump.
Does someone have any tips? Maybe something im missing?
thanks in advance!
Chris
Last edited by chkansas; Sep 30, 2024 at 07:14 AM.
