Fuel Pressure ???????

wideopen

wideopen

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A guy I know has a 02' 24V that we put a Fuel Pressure guage on the truck a month or two ago. It was an electronic guage, I used a schrader/banjo bolt at the VP44 to connect the sending unit.

Now my question:

With this set up and just the key turned on to activate the stock fuel pump, will I/or should I see any pressure?

This guy is real anal. And about to drive me nuts with this.
 
on mine, which is manual not electronic, but FP is FP, mine i flip the key and pump comes on i have a sudden spike in FP then drops back down until i fire the motor.
 
This is an electronic guage, and has to be reset, I can't run constant voltage.

Those of you with an Electronic guage where are you getting your power from? Is it constant Hot?
 
even if it is electric...it shouldn't read any pressure if there is no pressure there...that shouldn't change anything...
 
wideopen said:
With this set up and just the key turned on to activate the stock fuel pump, will I/or should I see any pressure?
Click to expand...

No you will only see pressure as you hear the pump run for a bit.
bump the key into the run position(Dont let the truck start) and the lift pump will run longer and will show Pressure.
 
wideopen said:
This is an electronic guage, and has to be reset, I can't run constant voltage.

Those of you with an Electronic guage where are you getting your power from? Is it constant Hot?
Click to expand...

No... I think I nabbed mine from the radio. My FP comes up when I flip the key on, but drops back down until I crank it.
 
You will see maybe 2lbs at best when the pump cycles for that split second.

If you want to check pressure and not start it. Just bump the starter but no start , this will make the pump run for about 25 seconds.

Use a test light and find a hot position in the PDC . Your two 6 gauge wires going to the PDC are hot as well.

The reason that it cycles this way is to not over pressurize the VP.
 
I went over this issue in a lot of detail. You should have a 2s full LP pressure surge (on mine, it is about 20 psi). Then it goes to zero. When you crank, the LP should operate for 25s at half pressure (stock LP or a smartly connected LP). If your aftermarket LP is on a relay from the stock LP harness, you will get full LP pressure for 25s. (And I think this is why we sometimes get hard starts when hot - the VP44 should not get full pressure to start the engine).
-P
 
I went with a key on hot also.

I have a FASS, but yes, I do see pressure when I key on.

Depending on if he has ever had the ECM flashed, the lift pump will run for about 2 seconds at key on, or up to about 8-10 seconds with key on.

In either case, you should see the gauge move.
 
OK here is what I came up with.

Because of the delay that this guage has(3-4 seconds after power), I put it on it's own switch. This way it gets full time power, and he can flip the switch to reset the Electroincs in the guage.

Seems to be working, and he seems to be happy.
 
Ha! Thats classic.. I guess if he is happy, that is what matters!!

Do you have to flip the switch on and off now when you first start it?

I wonder how many times he will forget to turn it back off and kill the batteries before he decides to go back to the way it was....
 
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