[Supras] Fuel pressure.

[Rich Peacock]

There should be a check valve in the fuel pump to prevent back flow.  
Fuel pressure should drop very slowly after the key is off, but loosing 
all pressure overnight is totally normal.  Loosing pressure quickly 
might indicate a leaking injector or bad fuel pump check valve.  If you 
shut the motor off and it takes a bit to restart while still hot, that 
could be some form of fuel vapor lock.

Easy test would be to place a jumper (paper clip) between B+ and Fp 
within the diag block.  This will send a 12v signal to the fuel pump 
when you turn the ignition on pre-priming the fuel system.  If that 
clears up your hard start problem, then you could check the voltage at 
the fuel pump (the Supra uses a resistor/relay to step between 9v and 
12v to the fuel pump) or it might be time to replace the fuel pump.  If 
the car is still hard to start, you might want to look for a weak 
ignition.  Replacing the plugs and wires.

Sean - once you do the 12v mod (putting 12v to the fuel pump via heavier 
gauge wire and relay when IGN is on), many Supras fire right up when you 
turn key.  Which actually might not be a bad idea for Vladimir's car 
either...
-Rich

Sean Cavanaugh wrote:
> far as I know, that's normal. after car is off, fuel flows backwards thru 
> the pump into the tank. first few seconds of cranking reprimes the line with 
> fuel and you're good to go. I have never heard of a MKIII with a stock pump 
> that starts right up without a little lag.
>
> -Sean
>
> ----- Original Message -----
> From: "Vladimir Ponomarev" <vladiborev at yahoo.com>
> To: <supras at supras.com>
> Sent: Thursday, October 18, 2007 6:07 PM
> Subject: [Supras] Fuel pressure.
>
>   
>> Hi guys. I have noticed a fuel pressure drop after my 91T with 170 kmiles
>> sits overnight in the garage or even after few hours after stop. It takes
>> time to build fuel pressure again and to crank her. Question: what is the
>> most likely cause of the pressure drop? I have switched to AFPR, but it
>> didn't help. What is my next bet?
>> Thanks.
>>
>> Vlad.
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>
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