Factory Five Racing Forum banner
1 - 5 of 5 Posts

·
Zipper-suited sun god and
Joined
·
2,033 Posts
Discussion Starter · #1 ·
When I first installed my fuel system, I plugged my FPR in out-of-the-box w/ no gauge (a compact EFI Aeromotive regulator). The car would start but not stay running. I purchased a timing light and fuel pressure gauge, set the base timing at 8* and plugged the gauge in. When the ignition was first turned to on, the pressure would spike off the gauge (0-60) and then drop to right back down to zero. I do not have a check valve in my supply line and am using a Mallory georotor external fuel pump. I adjusted the pressure to 40psi when the ignition is turned to "on" for the initial 3-seconds of fuel pump operation, but now during start the pressure reads zero until the starter is released then jumps back up to 40. what the heck is going on? Is this normal ops? On my Mustang (that has a check valve) pressure holds constant around 40 during start, during the key-on prestart pump ops, and even holds pressure for days (it's reading 30 now and I drove it last Monday or so).
 

·
Senior Charter Member
Joined
·
3,086 Posts
Have someone crank the car and confirm the pump is coming on during cranking (you might also be able to loosen the distributor and turn it like setting the timing). The EEC turns the pump on once it senses a PIP signal from the distributor.

If the pump does not start there may be a wiring or sensor issue.

Does the engine run? How does the fuel pressure behave if it is running?

Adding a check valve will make starting faster.
 

·
Zipper-suited sun god and
Joined
·
2,033 Posts
Discussion Starter · #3 ·
the engine doesn't run, hence my problem. I think I've got a wire grounding out, since I've noticed my PCM relay buzzing when the clutch is out but the ignition switch is on.
 

·
Blue Oval Scribe
Joined
·
9,177 Posts
How have you set the base timing at 8 degrees if the car will not stay running? Did you disconnect the SPOUT connector to check/set base timing?

How is the fuel pump wired and where is the fuel pump relay getting power? It sounds like it is possibly not getting power during cranking...

HTH...
Mark
 

·
Zipper-suited sun god and
Joined
·
2,033 Posts
Discussion Starter · #5 ·
It would crank and try to start but not stay running. the spout was out while setting the initial timing, yes.

The fuel pump is wired using the stock fuel pump relay (downstream of the buzzing pcm relay) and spliced in to the factory fuel pump harness. The fuel pump operates normally with the clutch in, it sounds like. I too am thinking it's not getting power during engine crank, but am not sure why. I have run and start functions tied in to the same ignition toggle switch, and the starter is wired to a pushbutton momentary switch.

Update: looks lke it's something in the mass-flo system that's grounding out. The buzzing goes away when the MAF harness is disconnected. I'm going to try to give Chris a call to see if it's ok to open up the box and peek around or if he'd rather I just mail the whole shebang back for TS/repair.
 
1 - 5 of 5 Posts
Top