Full Version: Should I check the fuel pressure?
I was having issues starting my 74 w/ newly built 2.0 w/ Djet and figured out my fuel pump went bad on me. I bought a newer 75-76 style (way cheaper) and it cranked right up. I broke in the cam, set the timing/idle and am installing my CVs so I can take this thing for a ride! It cranks right up and runs smooth...but it does seem to kick out a little black smoke when it is warm (white when first cranked, but it is cold out). Do I need to check the fuel pressure since I installed a new pump? Anything else to check? Could it be I just need to run this thing around the block for a bit? Thanks guys!
The pump doesn't determine the fuel pressure, the fuel pressure regulator does. I presume you properly converted the return line setup. The Cap'n
QUOTE(Cap'n Krusty @ Nov 12 2007, 11:38 AM) 
The pump doesn't determine the fuel pressure, the fuel pressure regulator does. I presume you properly converted the return line setup. The Cap'n
Yup...return line good to go. So assuming it was set correctly with the old pump, then I should be good. Anything else to check/adjust for the black smoke? Should I be concerned at this point?
Since you are breaking in a new engine, the answer would be yes. If to rich, it will wash the lubricant off cylinder walls and lead to non-seating rings (bluish white smoke). Black smoke is, of course, sign of an over rich condition.
To high a fuel pressure will result in an over rich condition and if it's really high (AFAIR above 36 lbs), it can over-ride the solenoid in the injector (called a leak).
To high a fuel pressure will result in an over rich condition and if it's really high (AFAIR above 36 lbs), it can over-ride the solenoid in the injector (called a leak).
QUOTE(SLITS @ Nov 12 2007, 08:57 AM)
Since you are breaking in a new engine, the answer would be yes. If to rich, it will wash the lubricant off cylinder walls and lead to non-seating rings (bluish white smoke). Black smoke is, of course, sign of an over rich condition.
To high a fuel pressure will result in an over rich condition and if it's really high (AFAIR above 36 lbs), it can over-ride the solenoid in the injector (called a leak).
I have to ask, Slits , this is the second time you have replied to a thread and mentioned a injector sticking OPEN due to high fuel pressures.
serious or sarcasm?
BTW, if the pump was failing and you adjusted the reg. to compensate then the FP might be too high causing a rich condition.
I don't screw around on tech questions ... I'm serious
You want to know how they work and the internals ... go to the library and read.
I've had them stuck open and stuck closed. I've had them fouled (clogged). I've had them where the solenoid is bad and they won't open.
The CSV has been known to be a culprit before. I just fixed an engine where the #1 plug was WHITE ... what would be your guess?
When you're guessing from miles away and don't have your hands on the vehicle, there are a multitude of things that can contribute to a situation. You need to check ALL of them.
You want to know how they work and the internals ... go to the library and read.
I've had them stuck open and stuck closed. I've had them fouled (clogged). I've had them where the solenoid is bad and they won't open.
The CSV has been known to be a culprit before. I just fixed an engine where the #1 plug was WHITE ... what would be your guess?
When you're guessing from miles away and don't have your hands on the vehicle, there are a multitude of things that can contribute to a situation. You need to check ALL of them.
QUOTE(SLITS @ Nov 13 2007, 11:15 AM)
I don't screw around on tech questions ... I'm serious
You want to know how they work and the internals ... go to the library and read.
I've had them stuck open and stuck closed. I've had them fouled (clogged). I've had them where the solenoid is bad and they won't open.
The CSV has been known to be a culprit before. I just fixed an engine where the #1 plug was WHITE ... what would be your guess?
When you're guessing from miles away and don't have your hands on the vehicle, there are a multitude of things that can contribute to a situation. You need to check ALL of them.
I know what the internals of a inj. looks like
If you know what the internals of an inj. is, then you would know that excessive fuel pressure would case it to SHUT not stick open.
Can you give an example of a problem you have run accross where excessive fuel pressure caused an inj. to stick OPEN?
All the problems you described above are not the result of too much FP.
They are the result of a failing injector, that's different.
you could take and 914 inj. and apply 60psi to it and it would work fine, they only start to have opening probs. at around 70psi.
Most of the flow rates for a 1.7 or 2.0 inj's. are taken at 43.5 psi., which is what modern fuel system pressures run.
Ok kids...
I stopped by and grabbed a pressure kit from Harbor freight on sale for 9 bucks
. Pressure was sitting steady at 36, so I adjusted it down to 30. I will crank it up after a few other tasks to see if the black smoke is gone
Thanks guys
I stopped by and grabbed a pressure kit from Harbor freight on sale for 9 bucks
. Pressure was sitting steady at 36, so I adjusted it down to 30. I will crank it up after a few other tasks to see if the black smoke is goneThanks guys
QUOTE(Bogaat @ Nov 13 2007, 12:54 PM)
Ok kids...
I stopped by and grabbed a pressure kit from Harbor freight on sale for 9 bucks
. Pressure was sitting steady at 36, so I adjusted it down to 30. I will crank it up after a few other tasks to see if the black smoke is goneThanks guys
@ 36 psi you increased the flow rat of the inj. by 73cc/min. YEP! that'll make her run rich.
QUOTE(toon1 @ Nov 13 2007, 11:42 AM)
QUOTE(SLITS @ Nov 13 2007, 11:15 AM)
I don't screw around on tech questions ... I'm serious
You want to know how they work and the internals ... go to the library and read.
I've had them stuck open and stuck closed. I've had them fouled (clogged). I've had them where the solenoid is bad and they won't open.
The CSV has been known to be a culprit before. I just fixed an engine where the #1 plug was WHITE ... what would be your guess?
When you're guessing from miles away and don't have your hands on the vehicle, there are a multitude of things that can contribute to a situation. You need to check ALL of them.
I know what the internals of a inj. looks like
If you know what the internals of an inj. is, then you would know that excessive fuel pressure would case it to SHUT not stick open.
Can you give an example of a problem you have run accross where excessive fuel pressure caused an inj. to stick OPEN?
All the problems you described above are not the result of too much FP.
They are the result of a failing injector, that's different.
you could take and 914 inj. and apply 60psi to it and it would work fine, they only start to have opening probs. at around 70psi.
Most of the flow rates for a 1.7 or 2.0 inj's. are taken at 43.5 psi., which is what modern fuel system pressures run.
What you just said is directly opposed to everything the rebuilders we sell to tell me. Enough said .... you appear to be the expert so carry on.
[quote name='SLITS' post='966369' date='Nov 13 2007, 04:09 PM']
[quote name='toon1' post='966287' date='Nov 13 2007, 11:42 AM']
[quote name='SLITS' post='966279' date='Nov 13 2007, 11:15 AM']
I don't screw around on tech questions ... I'm serious
You want to know how they work and the internals ... go to the library and read.
I've had them stuck open and stuck closed. I've had them fouled (clogged). I've had them where the solenoid is bad and they won't open.
The CSV has been known to be a culprit before. I just fixed an engine where the #1 plug was WHITE ... what would be your guess?
When you're guessing from miles away and don't have your hands on the vehicle, there are a multitude of things that can contribute to a situation. You need to check ALL of them.
[/quot
I know what the internals of a inj. looks like
If you know what the internals of an inj. is, then you would know that excessive fuel pressure would case it to SHUT not stick open.
Can you give an example of a problem you have run accross where excessive fuel pressure caused an inj. to stick OPEN?
All the problems you described above are not the result of too much FP.
They are the result of a failing injector, that's different.
you could take and 914 inj. and apply 60psi to it and it would work fine, they only start to have opening probs. at around 70psi.
Most of the flow rates for a 1.7 or 2.0 inj's. are taken at 43.5 psi., which is what modern fuel system pressures run.
[/quote]
What you just said is directly opposed to everything the rebuilders we sell to tell me. Enough said .... you appear to be the expert so carry on.
[/quote]
OK, maybe I'm in the wrong, explain
[quote name='toon1' post='966287' date='Nov 13 2007, 11:42 AM']
[quote name='SLITS' post='966279' date='Nov 13 2007, 11:15 AM']
I don't screw around on tech questions ... I'm serious
You want to know how they work and the internals ... go to the library and read.
I've had them stuck open and stuck closed. I've had them fouled (clogged). I've had them where the solenoid is bad and they won't open.
The CSV has been known to be a culprit before. I just fixed an engine where the #1 plug was WHITE ... what would be your guess?
When you're guessing from miles away and don't have your hands on the vehicle, there are a multitude of things that can contribute to a situation. You need to check ALL of them.
[/quot
I know what the internals of a inj. looks like
If you know what the internals of an inj. is, then you would know that excessive fuel pressure would case it to SHUT not stick open.
Can you give an example of a problem you have run accross where excessive fuel pressure caused an inj. to stick OPEN?
All the problems you described above are not the result of too much FP.
They are the result of a failing injector, that's different.
you could take and 914 inj. and apply 60psi to it and it would work fine, they only start to have opening probs. at around 70psi.
Most of the flow rates for a 1.7 or 2.0 inj's. are taken at 43.5 psi., which is what modern fuel system pressures run.
[/quote]
What you just said is directly opposed to everything the rebuilders we sell to tell me. Enough said .... you appear to be the expert so carry on.
[/quote]
OK, maybe I'm in the wrong, explain
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