Clogged fuel return line

[parkerbink]

After a slew of repairs to get my '92 cabrio running (and it is) I am down to a clogged return line.

The shop that got it this far wanted to replace the tank which I will do if I have to.

Does anyone have a solution to clear the line?

[e30davie]

Air compressor:)

[parkerbink]

They soaked it overnight with fuel system cleaner and blew the line unsuccessfully.

[e30davie]

I wonder how a fuel return line even gets clogged? was the car sitting for an extended period of time? is it full of rust?

If it is rust it might be worth replacing it....

[parkerbink]

Searching finds it to be common. I just got the car, unsure on it's sitting. I do know the PO had a fuel pump die on the freeway, starve the engine of fuel, blow a few valves (his story) he rebuilt the head replaced the timing belt, replaced the pump did a bunch of pm while you are in there etc and the car ran. Then it died and he was done.

I have replaced the CPS, ICV, MAF, FPR, injectors, plugs, coil fuel pump relay and ANOTHER fuel pump, both temp sensors, thermostat and I am sure more before taking it to the shop who replaced the throttle body and diagnosed the return being clogged.

He was unwilling to rod the line out which was a solution I found on Bimmerforums he was concerned about explosions.

[parkerbink]

This morning I opened the pump access panel and blew my compressor into the rubber hose connected to the hardline on top of the tank (I assume that is the return) I heard the gas "bubble" and did it a few times.

The shop said the motor would be starved for fuel after a few minutes. I let it idle for 10, then drove it for 5. It revs freely and seems fine.

About an hour ago I drove it around the block for 10 minutes, then went to the gas station and filled the tank all told 20 minutes plus of driving/engine running. It runs fine (although it still has the damn temp sensor CEL)

Should I consider it ok?

[cscracker]

Correct me if I'm wrong, but I wouldn't expect a clogged return line to cause fuel starvation. I'd expect it to cause extra load on the fuel pump and high fuel pressure.

[parkerbink]

He said it had high pressure and would eventually run out of gas. I ordered a gauge and will replace the tank if I have to.

[Kershaw]

I mean... eventually all cars run out of gas. Higher pressure would mean more fuel going through your injectors than the DME expects, so your car would run rich.

Put a white piece of paper behind your exhaust while idling. Does it get speckled in black? If it does you're running rich.

[parkerbink]

Thanks for the idea, on start up nothing, clean white envelope. After it warmed I put packing paper around the exhaust with enough to still be in front when revving pushed it away and nothing. No gas spitting out.

It had a horrible hard start and rough idle issue, resolved by a new throttle body. I am thinking it needed another day soaking on the carb cleaner so was not clear before I towed it home.

I ordered a fuel pressure gauge and am not driving it until I am sure it is ok.