Hey L98'ers...
Thread Starter
Instructor
Joined: Dec 2000
Posts: 124
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From: Huntsville Al
Hey L98'ers...
I've got an oil leak on one of the oil sending units that are attached to the rear of the engine. There are two to the left of the distributor at the rear side of the motor. One is positioned horizontal, the other is slightly vertical. The one leaking is the vertical one. Without my book tonight, what is this and what is its function? This is a test and you will be graded!!!
Le Mans Master
Joined: Nov 2000
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From: Chandler AZ
Re: Hey L98'ers... (LeadFoot)
Without my book... it is the oil pressure switch for the ignition... as in if you lose oil pressure when you are not supposed to this switch is wired to cut ignition power. How did I do?
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Re: Hey L98'ers... (billreid1@***.net)
Without my book... it is the oil pressure switch for the ignition... as in if you lose oil pressure when you are not supposed to this switch is wired to cut ignition power. How did I do?
You're right except that it kills the fuel pump, not the ignition!
:cool: :cheers:
Thread Starter
Instructor
Joined: Dec 2000
Posts: 124
Likes: 0
From: Huntsville Al
Re: Hey L98'ers... (LeadFoot)
OOOhhhh...A's for everybody. That was fast, now I can get to the store before they close and fix it tonight. Who needs a manual when I've got you guys. Thanks!!!
Drifting
Joined: Mar 2001
Posts: 1,636
Likes: 3
From: Lafayette IN
Re: Hey L98'ers... (Marcho Polo)
You're right except that it kills the fuel pump, not the ignition!
:cool: :cheers:
:cool: :cheers:
But yeah, they are supposed to kill fuel delivery at about 6psi. I guess mine was looking for vacuum--not pressure. Doesn't say much about this driver :eek:
Safety Car
Joined: Dec 2000
Posts: 3,767
Likes: 5
From: Jacksonville Fl
Re: Hey L98'ers... (HighHopes85)
It's supposed to work something like this:
1. Crank engine over by starter.
2. ECM turns on fuel pump relay for 10 seconds.
3. Oil pressure builds up and closes the switch, thereby holding the fuel pump relay on.
The switch unit turns on at like 6-12 PSI, but turns off at a lower pressure. This pretty much makes it ineffective as an oil pressure protection device, because I think like maybe 1-2 PSI is all it needs to keep the fuel pump running.
Also, if you reprogrammed the ECM...could the fuel pump relay oil pressure time-out get disabled by mistake?
In otherwords...it's to keep the engine from starting without oil pressure...not to shut it down on a loss of pressure.
1. Crank engine over by starter.
2. ECM turns on fuel pump relay for 10 seconds.
3. Oil pressure builds up and closes the switch, thereby holding the fuel pump relay on.
The switch unit turns on at like 6-12 PSI, but turns off at a lower pressure. This pretty much makes it ineffective as an oil pressure protection device, because I think like maybe 1-2 PSI is all it needs to keep the fuel pump running.
Also, if you reprogrammed the ECM...could the fuel pump relay oil pressure time-out get disabled by mistake?
In otherwords...it's to keep the engine from starting without oil pressure...not to shut it down on a loss of pressure.
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Drifting
Joined: Mar 2001
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From: Lafayette IN
Re: Hey L98'ers... (BBA)
In otherwords...it's to keep the engine from starting without oil pressure...not to shut it down on a loss of pressure.
I was unaware of that. The main driving force behind my post was to make sure other people don't do something stupid ;)
But no, I haven't found anything in the chip that would disable/enable a timeout function. Heck, if it works like you mentioned, I probably had siphon-action still behind the fuel. My problem was in existence long before the total demise. It is just the fact that one completely non-existent cam lobe must have been somewhere else in the engine. :cheers:
Burning Brakes
Joined: Feb 2000
Posts: 824
Likes: 2
From: Camden SC
Re: Hey L98'ers... (billreid1@***.net)
Hello all,
This can be a confusing system. Power to the fuel pump can be supplied through 2 circuits. One is the fuel pump relay, controlled through the ECM. The second and back up method is when the oil pressure reaches 4 psi, an additional power source is available to the fuel pump. Should the relay fail, a code 54 should set however the car should continue to run if it has 4 psi oil pressure and the switch is functioning properly. With the key on, engine off, the ECM will power the fuel pump for 2 seconds. If no crank signal or engine run signal is received, no more power to the control side of the fuel pump relay. Long cranking times may be due to inoperative fuel pump relay and the engine may take some time in building 4 psi pressure.
This switch will NOT shut off the engine during low oil pressure with fuel pump relay functional. Hope this helps.
For more on this subject, see page 6E3-C2-2 (VIN 8) or schematics around page 8A-20-6 (MY 90 service manual). The factory service manuals are great.
Keep the faith.
dlmeyers 90 coupe zf6 3 sped shocks
[Modified by dlmeyers, 8:52 AM 6/24/2002]
This can be a confusing system. Power to the fuel pump can be supplied through 2 circuits. One is the fuel pump relay, controlled through the ECM. The second and back up method is when the oil pressure reaches 4 psi, an additional power source is available to the fuel pump. Should the relay fail, a code 54 should set however the car should continue to run if it has 4 psi oil pressure and the switch is functioning properly. With the key on, engine off, the ECM will power the fuel pump for 2 seconds. If no crank signal or engine run signal is received, no more power to the control side of the fuel pump relay. Long cranking times may be due to inoperative fuel pump relay and the engine may take some time in building 4 psi pressure.
This switch will NOT shut off the engine during low oil pressure with fuel pump relay functional. Hope this helps.
For more on this subject, see page 6E3-C2-2 (VIN 8) or schematics around page 8A-20-6 (MY 90 service manual). The factory service manuals are great.
Keep the faith.
dlmeyers 90 coupe zf6 3 sped shocks
[Modified by dlmeyers, 8:52 AM 6/24/2002]