fuel check valve location install

[doctorx69]

When i first got my e30, it had bad fuel pumps and fuel tank. They were replaced a couple of years ago (about 1000 miles). I put in Spectra Premium pump and tank. STarting and running is fine cold. Warm start after sitting 15 mins is hard, but it does start and run fine afterwards. It just dawned on me today that the replacement pump doesnt have a check vavle. I need to add one externally but not a clue where it needs to go. Does it go before the fuel tank (ie fuel return line) or after the tank or pumps?

FPR is new.

[richardodn]

Check valve is to keep the supply line pressurized. You would place it in the supply line after the main fuel pump. Just to keep it pictured in your head, flow is:
tank -> pump -> filter -> fuel rail -> fuel pressure regulator (FPR) -> return to tank
Install after pump and before filter

[superj]

but if it starts fine cold, the check valve is not the problem. a warm start issue seems like it would be the temp sensor for the ecu

[doctorx69]

i looked at picture of the pump i bought... no check valve. i changed out the temp sensor about last fall.

[superj]

that's weird that it starts fine cold though. normally they leak down over night, especially.

[doctorx69]

yea... i thought so too... but looking at other forums... seems to be a quirk of the e30. if the car is dead cold, then it starts fine but if you try to restart 15-60 mins after stopping, this is what happens. The bmw pump has a check valve on the pump. Mine doesnt. But when i replaced it, i didnt know what i do now.

[doctorx69]

it does crank a bit cold though.. not anything like warm.... i got check valve in... just need to install it.

[doctorx69]

just for clarification: i have 2 pump system. do I put it between the hi pressure pump and filter or between the lift and high pressure pump?

[superj]

Right after the lift pump is where i put one in ours

[clarkitect]

If if starts fine cold but hard to start and runs poorly initially when warm, sounds like you have a vapor lock condition cause by a bad fuel presssure regulator. Had these symptoms a few years ago, swapped in a spare FPR I bad and problem solved.

[doctorx69]

i just took out the fuel shock absorber thingy... and put the check valve there. In my limited testing yesterday, it seemed to have fixed the problem. BTW... new fpr, pumps, filter, tank, injectors, hoses last year... not even 1000 miles on them. I had my slave cylinder blow the seal so i have had a chance to fully test yet.

[doctorx69]

that fixed it. happy now!