Checking fuel pump voltage
#1
too stock
Thread Starter
Join Date: Jun 2005
Location: Salina, KS
Posts: 200
Likes: 0
Received 0 Likes
on
0 Posts
Checking fuel pump voltage
I did some reading (and a little seaching even) and i was reading that i should make sure that my fuel pump was getting all the power it needed on my 89 TII. I checked my batt w/ the car off, 12.8 volts. So i went to check the fuel pump. I had the key on so it should be drawing power from the pump and i cant figure out which of the four holes to put the pos and neg on. I know it would make sense to just keep trying them all until i got a reading, and i did do that but i still couldnt get a reading
what am i doing wrong?
what am i doing wrong?
#3
I'm a boost creep...
Join Date: Jan 2002
Location: Auckland, New Zealand
Posts: 15,608
Likes: 0
Received 8 Likes
on
8 Posts
The fuel pump only gets power when the engine is running or cranking. Plus it has a two-speed system that drops the voltage sent to the pump at low load. So the best thing to do is monitor the fuel pump voltage while driving.
What I did was to terminate the wires at one end of a length of speaker cable with male spade terminals, which slip into the back of the fuel pump plug (blue/green and black wires), run the wire to the passengers seat and twist the other end around the DMM probes. Then drove and watch the voltage. It should be ~9V at idle at cruise and >12V under load. Mine switched at 2-3psi boost.
What I did was to terminate the wires at one end of a length of speaker cable with male spade terminals, which slip into the back of the fuel pump plug (blue/green and black wires), run the wire to the passengers seat and twist the other end around the DMM probes. Then drove and watch the voltage. It should be ~9V at idle at cruise and >12V under load. Mine switched at 2-3psi boost.
#4
Lives on the Forum
Look for the two thickest wires.
If your DMM has auto polarity, it won't matter.
If you see a negative, you can reverse it for proper readings.
Or, hell, just ignore the "-" sign.
You really need to monitor the voltage when in boost / WOT.
Connect everything semi-permanently and go out for a drive.
It would help to have a friend to read the DMM for you for safety...
-Ted
If your DMM has auto polarity, it won't matter.
If you see a negative, you can reverse it for proper readings.
Or, hell, just ignore the "-" sign.
You really need to monitor the voltage when in boost / WOT.
Connect everything semi-permanently and go out for a drive.
It would help to have a friend to read the DMM for you for safety...
-Ted
Thread
Thread Starter
Forum
Replies
Last Post
trickster
2nd Generation Specific (1986-1992)
25
07-01-23 04:40 PM
immanuel__7
2nd Generation Specific (1986-1992)
89
09-05-15 10:23 AM
befarrer
Microtech
3
08-22-15 05:52 PM