Frank II
Active Member
how do I know if the fuel pressure sensor is bad. Car will start w/ starter fluid. Mechanic says good pressure at rail. ECU checked twice and is good. Pulse generator good.
pressure sensor
- Thread starter Frank II
- Start date
Cold start valve?
Does the cold start valve work?
Or, Fuel draw down? If I leave mine the fuel drains back so I have to key on and wait a while for it to charge / prime itself, then it starts.
C
Does the cold start valve work?
Or, Fuel draw down? If I leave mine the fuel drains back so I have to key on and wait a while for it to charge / prime itself, then it starts.
C
Bwana
Well-Known Member
Yes, same with mine after sitting overnight. I generally turn the key "on" and wait a moment before going to "start" to let the fuel pressure build up. You can hear the pump and relay if you listen very carefully
Did you mean manifold pressure sensor?
Frank II
Active Member
I am told the fuel pressure sensor may be my problem, how could I check this?
I'm sorry- there is a fuel pressure regulator but no sensor. If you have good pressure at rail the regulator is working.
Fuel pressure - regulator - is tested by the use of an inline pressure gauge.
Manifold pressure sensor is typically tested by applying vacuum to the unit to determine whether its internal bellows remain sealed by holding vacuum. Secondary tests involve measuring resistance as varying manifold pressure is applied.
http://www.e9coupe.com/tech/dljet/dljet.html
Although your problem is likely fuel injection related,"ether" does not automatically or completely guarantee that your ignition system is functioning properly. That said, assuming the subject fuel injection system is a "D-jet," a manifold pressure sensor requires vacuum to function. In other words, check for vacuum leaks before testing your manifold pressure sensor.
Significant fuel pressure is required for the system to function. Fuel pressure issues may involve adjustment or replacement of the pressure adjuster; however, they can be caused by plugged filters (search the archives) or even possibly a failing pump or a finicky pump relay.
hth
Manifold pressure sensor is typically tested by applying vacuum to the unit to determine whether its internal bellows remain sealed by holding vacuum. Secondary tests involve measuring resistance as varying manifold pressure is applied.
http://www.e9coupe.com/tech/dljet/dljet.html
Although your problem is likely fuel injection related,"ether" does not automatically or completely guarantee that your ignition system is functioning properly. That said, assuming the subject fuel injection system is a "D-jet," a manifold pressure sensor requires vacuum to function. In other words, check for vacuum leaks before testing your manifold pressure sensor.
Significant fuel pressure is required for the system to function. Fuel pressure issues may involve adjustment or replacement of the pressure adjuster; however, they can be caused by plugged filters (search the archives) or even possibly a failing pump or a finicky pump relay.
hth
Frank II
Active Member
thanks Lloyd, I am going to investigate this path.
Frank II
Active Member
Again, Car has new fuel pump, pressure at rail is good, ECU checked twice, pulse generator on distrib good. will start immediately w/ starter fluid. injectors not getting pulse. all 6 cant go bad at once. I do appreciate all information and help.
Any and all info is appreciated, thank you all!!
Any and all info is appreciated, thank you all!!
Quick test for you.
With key at run position but car not running use your hand at throttle body to go to full throttle rapidly several times. You should hear many many small clicks. Those clicks are your injectors firing. Yes or no?
Next test- find the vacuum line running from the mps (looks like a hand grenade behind brake booster)
Connect vacuum hand pump to hose and check if mps holds vacuum.
Yes or no?
With key at run position but car not running use your hand at throttle body to go to full throttle rapidly several times. You should hear many many small clicks. Those clicks are your injectors firing. Yes or no?
Next test- find the vacuum line running from the mps (looks like a hand grenade behind brake booster)
Connect vacuum hand pump to hose and check if mps holds vacuum.
Yes or no?
When you describe the injectors as not receiving any pulse, do you mean there is no measurable signal - or, you don't hear the typical "click" noise associated with a pulse? It's also a little unclear (to me) how you tested the ECU.
In addition to confirming that the manifold pressure sending unit holds a vacuum, I would want to ensure that all the electrical connections are sound. That includes the connection to the manifold pressure sending unit, the throttle position sensor, the loom connection to the ECU and - if you have one, any modular wiring connection at or near where the wiring enters the passenger frame rail (near the exhaust manifold).
