If your 944 vacuum system is leaking and not in top notch condition, your Fuel Pressure Regulator will never work correctly as it is vacuum controlled. The vacuum and the fuel and several other systems in a 944 (especially in the 944 Turbo) are inextricably intertwined. If your car only has trouble starting and not idling or running, then maybe it is just the fuel check valve has a tiny bit of debris that keeps this valve slightly open when it should be off - allowing fuel to gravity-flow from the rail back into the fuel tank (the fuel pump and the check valve are both inside the tank). On the 944, try just turning the ignition key to the 2nd position (not the 3rd = start) for about 15-30 seconds before you engage the starter. Listen for a slight whirring sound - that is your fuel pump running. If your car quickly starts after allowing the fuel pump to run and pressurize your fuel rail, you most likely have a compromised check valve. Aftermarket external check valves are available at reasonable prices that can be placed in the fuel line to provide a proper check valve action. Make sure you put the external check valve in the correct fuel line - the high pressure line fed by the fuel pump, not the low pressure return line. Be extremely careful regarding spilled gasoline and the resulting fire hazard. BTW, Lindsey Racing sells a very fine kit of premium grade silicone hoses to replace every vacuum hose in the 944 or 951. This is Porsche money well spent.
Thanks for the insight, but I have since found the issue and fixed it. My ECU was fried due to the main engine to chassis ground being left undone. When I replaced the alternator, it sent current through the ECU and fried it due to this. I just slapped another ECU in there and what do you know! She works!
Correction: to have the (1985.5 + later) 944 fuel pump to run prior to starting and for fuel pressure testing, the DME relay must be removed and a jumper installed. See www.clarks-garage.com/shop-manual/fuel-01.htm
added tip...(Unless the car has sat for a while) pull the DME or fuel pump relay/fuse and then crank the engine, it will get rid of any residual fuel pressure. Thanks for the tip on that LR adapter. Im going to add an autometer electronic sender to the end of mine. I want to be able to read the fuel pressure form the inside of the car.
Yep, I did that when I was rebuilding the engine to not create a mess, but It always did. I kinda just cut my losses and stopped doing it because it was essentially the same outcome for more work. Still a great tip to keep everything clean!
ok so installed the Lindsey Racing gauge and for some reason now my hood doesn't close correctly...hood hitting top of gauge...i have a 1988 944 base non-turbo...your opinion please...
My hood is not adjusted properly, so maybe there is more room for the gauge, but I believe the top of my gauge slightly makes contact with the hood as well. It hasn't caused me any issues like yours has so I haven't done anything about it, but It might be worth it to reach out to Lindsey Racing to have them weigh in on the issue.
@@johndeltoro7990 yeah, the elbows included are for the S2 models I believe because the gauge would be relocated to an unusable area if you used them on our cars. Let me know what they say if you get through to them.
@@TheMileHighMechanic just spoke with Lindsey Racing, and the brass elbows supplied are used for the exact problem i'm having...use them to clear the hood
If your 944 vacuum system is leaking and not in top notch condition, your Fuel Pressure Regulator will never work correctly as it is vacuum controlled. The vacuum and the fuel and several other systems in a 944 (especially in the 944 Turbo) are inextricably intertwined. If your car only has trouble starting and not idling or running, then maybe it is just the fuel check valve has a tiny bit of debris that keeps this valve slightly open when it should be off - allowing fuel to gravity-flow from the rail back into the fuel tank (the fuel pump and the check valve are both inside the tank). On the 944, try just turning the ignition key to the 2nd position (not the 3rd = start) for about 15-30 seconds before you engage the starter. Listen for a slight whirring sound - that is your fuel pump running. If your car quickly starts after allowing the fuel pump to run and pressurize your fuel rail, you most likely have a compromised check valve. Aftermarket external check valves are available at reasonable prices that can be placed in the fuel line to provide a proper check valve action. Make sure you put the external check valve in the correct fuel line - the high pressure line fed by the fuel pump, not the low pressure return line. Be extremely careful regarding spilled gasoline and the resulting fire hazard. BTW, Lindsey Racing sells a very fine kit of premium grade silicone hoses to replace every vacuum hose in the 944 or 951. This is Porsche money well spent.
Thanks for the insight, but I have since found the issue and fixed it. My ECU was fried due to the main engine to chassis ground being left undone. When I replaced the alternator, it sent current through the ECU and fried it due to this. I just slapped another ECU in there and what do you know! She works!
Correction: to have the (1985.5 + later) 944 fuel pump to run prior to starting and for fuel pressure testing, the DME relay must be removed and a jumper installed. See www.clarks-garage.com/shop-manual/fuel-01.htm
@@TheMileHighMechanic Great news MHM !
added tip...(Unless the car has sat for a while) pull the DME or fuel pump relay/fuse and then crank the engine, it will get rid of any residual fuel pressure. Thanks for the tip on that LR adapter. Im going to add an autometer electronic sender to the end of mine. I want to be able to read the fuel pressure form the inside of the car.
Yep, I did that when I was rebuilding the engine to not create a mess, but It always did. I kinda just cut my losses and stopped doing it because it was essentially the same outcome for more work. Still a great tip to keep everything clean!
ok so installed the Lindsey Racing gauge and for some reason now my hood doesn't close correctly...hood hitting top of gauge...i have a 1988 944 base non-turbo...your opinion please...
My hood is not adjusted properly, so maybe there is more room for the gauge, but I believe the top of my gauge slightly makes contact with the hood as well. It hasn't caused me any issues like yours has so I haven't done anything about it, but It might be worth it to reach out to Lindsey Racing to have them weigh in on the issue.
@@TheMileHighMechanic I definitely will reach out to them but they do include some elbows with kit just not sure how that works either
@@johndeltoro7990 yeah, the elbows included are for the S2 models I believe because the gauge would be relocated to an unusable area if you used them on our cars. Let me know what they say if you get through to them.
@@TheMileHighMechanic just spoke with Lindsey Racing, and the brass elbows supplied are used for the exact problem i'm having...use them to clear the hood
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