| JoMoSqBk |
Fri Oct 01, 2021 6:31 am |
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My 73 has been not wanting to start randomly for the past two months it would run fine but then it would act like it was flooded/vapor locked and not start until it sat for a few hours.
Fast forward to a few weeks ago it now will hardly ever start, once it starts it seems to run okay though, however I'm nervous to go too far from my garage and haven't been turning it off anywhere. I checked the fuel pressure as it seems to be fuel related and it is 29 PSI. I unplugged the injectors one by one and can get a little more fire and by unplugging #3 it would run; I installed a new FJ119 injector into the #3 position and no change. If I pull the fuel line the car will start and run through the fuel in the engine without issue.
I've checked for any obvious vacuum leaks, the coil is producing good steady spark so I am not sure where else to go. I have the E2000 fuel pump and I did install an inline check valve to try an reduce priming but I've since removed that as by general rule is when something breaks check the thing you messed with most recently first. |
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| Mike Fisher |
Fri Oct 01, 2021 7:26 am |
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Check your fuel sock in the tank that it doesn't have crud gathered around it.
Check your fuel return line that it's not getting plugged up with crud. |
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| raygreenwood |
Fri Oct 01, 2021 12:24 pm |
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JoMoSqBk wrote: My 73 has been not wanting to start randomly for the past two months it would run fine but then it would act like it was flooded/vapor locked and not start until it sat for a few hours.
Fast forward to a few weeks ago it now will hardly ever start, once it starts it seems to run okay though, however I'm nervous to go too far from my garage and haven't been turning it off anywhere. I checked the fuel pressure as it seems to be fuel related and it is 29 PSI. I unplugged the injectors one by one and can get a little more fire and by unplugging #3 it would run; I installed a new FJ119 injector into the #3 position and no change. If I pull the fuel line the car will start and run through the fuel in the engine without issue.
I've checked for any obvious vacuum leaks, the coil is producing good steady spark so I am not sure where else to go. I have the E2000 fuel pump and I did install an inline check valve to try an reduce priming but I've since removed that as by general rule is when something breaks check the thing you messed with most recently first.
There are a handful of things in here that do not make total sense:
Quote: My 73 has been not wanting to start randomly for the past two months it would run fine but then it would act like it was flooded/vapor locked and not start until it sat for a few hours.
OK...I get that you are not sure which...but just for anyone looking on...flooded and vapor locked are not the same....and ....fuel injected engines....it would be exceedingly rare to get vapor lock unless the ambient heat is very high and the car has sat for DAYS.
I capitalized "DAYS" because if the fuel pressure regulator (which is a check valve) and teh check valve in the pump are functioning properly.....fuel pressure should drop from 28 psi to about 23 psi right after shut down. With age...it may drop to 20-ish.
Overnight it should not drop below about 18 psi. In another day or two....roughly 13-15 psi. The 2-3 second pump buss on starting should get you minimum 20-23 psi for start up.
You can only get "vapor lock" if the line pressure drops below about 8 psi...and again...only if its raging hot outside like in the 'burbs in Phoenix.
A quick check of this is to let the fuel pump buzz...turn off the key and let it buzz again. Maybe even do 3 cycles. If it starts more normally....your fuel pressure is bleeding down. It means either the check valve in the pump or the fuel pressure regulator are bleeding down.
Most probably.....FLOODING is the problem...see below.....
Quote: If I pull the fuel line the car will start and run through the fuel in the engine without issue.
This should not even be possible. Removing the fuel line (I am assuming you mean from the ring main and/or the fuel pump)..... There should not be enough fuel in the engine to get it to do more than sputter.
With the fuel line removed anywhere in the system other than the return line.....you will have no fuel pressure. This mean "0" injection is possible....no fuel.
So....if it starts and runs even for a few seconds or so...it means that what fuel pressure you had in the lines (and you are supposed to have some fuel pressure)...has leaked out into the intake ports.
If it was only one leaking injector...and this can happen....it would only bang on one cylinder. If the engine is starting....with a fuel line disconnected and no pressure....and it runs evenly....it means that most probably the cold start injector is leaking....bleeding off your line pressure and flowing into the intake manifold which feeds all four cylinders.
Quote: I checked the fuel pressure as it seems to be fuel related and it is 29 PSI. I unplugged the injectors one by one and can get a little more fire and by unplugging #3 it would run; I installed a new FJ119 injector into the #3 position and no change. If I pull the fuel line the car will start and run through the fuel in the engine without issue.
It is not just running pressure that is important. You need to connect a gauge...run the car....check it while running...then shut it off...and watch the gauge. It should operate as i described above.
If the line pressure drops after shut down and keeps dropping......you need to test the whole fuel loop. You may need help to do this. The easiest way is to add a longer line to the return line and loop it into the engine compartment.
Run the car...note the running pressure....shut the engine off and IMMEDIATLY crimp the return line. If the fuel pressure stays rock solid.....you know its not the check valve in the pump.....and the pump SHOULD already have a check valve installed in the outlet port. If it drops...you have a leak somewhere.
The second thing to do is the same test as above...but crimp the feed line from the pump immediately after shut down. It should drop maybe to 20-23 psi and stay there. If it does...it means your fuel pressure regulator is operating properly. If it keeps dropping.....you either have a defective regulator...or a leak at one of the injectors between the inlet feed from teh pump and the regulator.
The proper check for injector leaks ......is to pull all five of them including the cold start.....lay the tips on rags....blip the keep a few times and observe the tips for dripping or spraying. Ray |
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