I have a 32' Ford Roadster that has a early Street & Performance 5,7L TPI engine. It is a speed density system. I am thinking (from what I have found) that they used an external pump when the car was built. I have not found it yet, as I think the interior will have to be removed to access the pump. Symptom: When starting I cycle the key and the pump runs for a few seconds (normal) I then crank and it will not fire up. If I release the starter and crank it a second time, it starts and runs good. I noticed that when I turn the key on the pressure will rise (fuel rail gauge) to about 40 psi, BUT it then rapidly drops to about 10 psi. The regulator has been rebuilt (by previous shop) and it appears to respond normally. 40+ at idle and rapid rise with quick throttle opening. I am thinking that the pump bleed down check valve is not doing it's job. It has been long time since I've worked on these, so any insight from fellow members is much appreciated. BTW, Merry Christmas!

 

It's possible the pump may not have a check valve; some don't. You can get an in-line one fairly inexpensively.

You can also crank the car sooner (during the 2s prime) in hopes to catch it during that timeframe. No reason to wait for it to finish priming.

 

What he said ^^^


or if you are tuning it, it sounds like you can add crank pulsewidth to compensate for lower pressure or just crank to start immediately and skip prime

 

It doesn't matter if it bleeds down when off. As long as it maintains maintains 43.5 psi with the regulator disconnected. Your problem appears to be that the pump isn't running when cranking (at least initially). If it's wired like a stock TPI system then it has a failsafe for the fuel pump power that runs through the oil pressure switch. A common symptom of primary fuel pump power loss is extended crank time as the oil pressure failsafe requires that the engine build oil pressure to the switch before power to the pump is turned on.

GD

 

is there any work around ?
mine has a long crank time before it will fire.
everything and i mean everything is new
fp inj dis coil module map mat tps iac ecm prom tempsen
and even the ignition switch on the back of the colum

 

Work around? Sure - you can send ignition switched power to the pump. And when you wreck the car the pump will keep right on pumping fuel onto the fire in your engine bay while you are unconscious in the drivers seat about to become a human spare rib.

it would be best if you fix the fuel pump relay and it's associated wiring. But it's totally your funeral so dealer's choice.

GD

 

What year?

If its 85-88 TPI then could be your cold start injector is inop. Potentially move to corrected 89 programming and plug off 9th injector.

89 TPI? There's an adjustment in the programming that you can do. Tuned Performance in my signature can do it. It waits for 8 reference pulses before enriching the startup fuel mixture by default.

90+ eh i dont know SD setups that well

If you are losing pressure like OP, install an in-line check valve or a pump with one. Walbro 255 or the Racetronix RXP255e have them

 

its a 92 ta 305
not quite what i was getting at didnt know it was there for that reason lol
the fp relay on the other hand what would i be looking for there?
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i doubt the oil saftey switch is delaying it that long. You could program the chip to start injection earlier and put more in so it starts faster.

Basically what was said above