Fuel problem, and I doing this right?

[blocke]

Yesterday I finally had time to dive into my hard-start issue. It takes a seriously long time of cranking, sometimes 3 10-second bursts to get my car to turn over. Once it does, it runs and idles fine.

So I suspect that I am losing fuel pressure when the car sits. Either the check-valve in the fuel pump, or perhaps the FPR is bad.

Here is what confuses me:
I jumpered my fuel pump relay to make sure pump was getting power. Had the supply fuel line to the rail disconnected and in a bucket to measure flow.
Key ON, jumper Pins 30 & 87 on the middle relay (in group of 3 towards front of fuse box) right? Nothing happens. That is the proper procedure right?

Second, I thought that the fuel supply went into the FPR, and then the FPR regulated rail pressure by modulating what fuel went INTO the rail.
However, I think I had it backwards. The supply goes into the rail, and the FPR regulates the pressure modulating how much LEAVES the rail into the return? Is that correct?
If these were switched, would my car still start and run?

I put the relay back, and measure voltage at the pump when cranking, and it is getting power. So I think maybe the FPR is bad?
I'm at a loss, need input on where to focus my efforts.

[603Racing]

Fuel to rail (on back side of motor), then to FPR (front side of motor), then return line, in that order.

You can check the vacuum line for the FPR, if it has fuel in it then you know for sure the FPR is bad. It could be bad even if there is not fuel in the vacuum line. A bad FPR can definitely cause your hard start symptom.

FPR's aren't too expensive, buy one and try it.

[blocke]

Fuel to rail (on back side of motor), then to FPR (front side of motor), then return line, in that order.

You can check the vacuum line for the FPR, if it has fuel in it then you know for sure the FPR is bad. It could be bad even if there is not fuel in the vacuum line. A bad FPR can definitely cause your hard start symptom.

FPR's aren't too expensive, buy one and try it.

My rail just has one inlet on the front, just under the FPR. Then the actual FPR.

My FPR vacuum line doesn't have fuel in it, and idle will change if I unhook it.
I do have a replacement I scored on the cheap. I'll throw it on and see if that helps.

[jlevie]

630Racing is correct as to the operation of the fuel system. Though in this case the supply nipple on the rail is next to the FPR.

Jumpering 30 & 87 on the fuel pump relay socket with the key on should power the pump. If that connection has power and fuel isn't flowing out of the supply line to the rail there is a problem with the fuel filter, supply line, pump, or wiring to the pump. Further diagnostics will be necessary to determine the cause.

[blocke]

Small update on this:
I was following the test procedures in the Bentley, and could not figure out why I was not getting voltage when testing the fuel pump relay. Well after some investigation, I discovered that at some point in my cars previous life, some dumbass swapped the fuel pump relay and the O2 Sensor heater relays positions.
SO this entire time I have been jumpering the center relay, wondering why my pump wont run...and it was the wrong relay.

Still having the hard start issue, but my pump and relay has passed all the flow/electrical tests. So I think it's the FPR. Swapped in a replacement last night to test if it maintains pressure better. I'll try starting the car after work today to see if it worked.

[603Racing]

630Racing is correct as to the operation of the fuel system. Though in this case the supply nipple on the rail is next to the FPR.

Jumpering 30 & 87 on the fuel pump relay socket with the key on should power the pump. If that connection has power and fuel isn't flowing out of the supply line to the rail there is a problem with the fuel filter, supply line, pump, or wiring to the pump. Further diagnostics will be necessary to determine the cause.

Doh! Yep, you are correct, i was picturing my e24 fuel rail instead of my e30 fuel rail. The indexing in my brain must be fried from too much e24 troubleshooting. Sorry about the bit of miss-information. Hope your car starts after work!