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Discussion Starter #1
Can anyone tell me what happens (signs and symptoms) when a fuel pressure regulator goes out. I am having some strange things going on and was wondering if I need to change it out. My car is an 82 L-Type, which I got running and registered last month. The engine when cold takes some cranking and pumping the gas pedal (kinda like my old 50's trucks). Once started, it idles smooth and drives like a dream. Once warmed up, it starts very quickly. Every once in a while, day or night, I'll be driving the car and the gas pedal response gets less and less until it stalls the engine (very much the same as running out of gas). I shut the car off for 10 to 15 minutes, re-start the engine, and it runs great with full power and throttle response, until it decides to crap out again. I changed the fuel pump and fuel filter out when I got her running in August of 2009. Would the hard starting and choking out / stalling issues be caused by a faulty Fuel Pressure Regulator, defective fuel pump, or air in the fuel lines (vapor lock)? What else would cause the above events to happen? I have never worked on such a damn picky car before. I love her when she runs and I hate her when she wont. :32:
 

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did u check the basics? plugs? wires? distribuitor cap, rotor? air filter? coil? igniter? many things can cause similar problems.
 

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Discussion Starter #3
I replaced the Plugs, Wires, Distributor, Distributor Cap, Rotor, Ignitor, Coil, Timing Belt, Battery and the ECU.
 

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Intake air related?
Have you/Can you try swapping AFMs?
An erratic and faulty TPS sensor could also mess up your mixture.
How about checking the movement of the butterfly valve inside the throttle body, and cleaning out the crud build up inside?
 

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Discussion Starter #5
I have not changed out the AFM yet. A re-built one is almost $300 bucks and there are no 82 - 86 Supras in the state of Utah that I can pull parts off. Where should I start (AFM, TPS or Fuel Pressure Regulator)?
 

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I have not changed out the AFM yet. A re-built one is almost $300 bucks and there are no 82 - 86 Supras in the state of Utah that I can pull parts off. Where should I start (AFM, TPS or Fuel Pressure Regulator)?
If you're going to try this, checking the air side of the equation, it won't cost you anything and it's relatively easy to:
a) Remove, clean (or replace - that will cost) the air filter.
b) Remove intake pieces in front and behind the AFM, check for tears, obstructions
c) Check the connector on the AFM, has clean contacts and plugs in solidly to the AFM.
d) With intake pieces off, check AFM door so that it opens, and springs back w/o any obstructions. Good spray of carb cleaner wouldn't hurt.
e) With intake pieces off, look inside the Throttle Body, move mechanism to check that the butterfly valve opens closes w/o obstructions. Again, cleaning it out with a rag/carb cleaner wouldn't hurt. Removing it complete is best way to clean it.
f) TPS can be checked w/o removing the TB, check per TSRM:
http://www.cygnusx1.net/Supra/Library/TSRM/MK2/manual.aspx?S=FI&P=63
If you do have to adjust it, it's tricky to take off while the TB is installed because of access to the bottom mounting screw. Taking off the TB is actually pretty easy. You will need some feeler gauges to recalibrate the TPS on the TB.
g) You may also want to check the two sensors up at the front of the block, by the distributor: the coolant temp and injector timer. There are resistance values that are also on the TSRM, which will tell you if they are at spec (at nominal temps anyway).

If none of the above fixes the issue, well at least it is not for naught, as it's a good idea to check/clean those areas anyway.

If you want to try an AFM swap, they show up on ebay all the time, and am sure you can find a spare from some of the other owners here, at a reasonable price.

Hope that helps.
 

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I doubt it is your AFM. Check it with a multi meter (see Emissions Manual in my signature). I'm wondering if it is the ignitor you changed. Try putting the original one back in and seeing if that helps.
 
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