Silly fuel pump assembly question

It's loosely regulated relative to intake manifold vacuum, so that sounds reasonable.
 
When running fine, here is a screen shot of my '03.

fullsizeoutput_2bd.jpeg


Added in one (Different setup) to show relative to MAP


fullsizeoutput_2a7.jpeg
 
So, it is about 67 degrees. It took her out on the expressway and was driving between 65-70. The fuel pressure was always the same. Between 39-41-ish psi. Judging by the graphs above, mine seems low. Also, I had a U code about not being able to communicate with my fuel pump. Not sure if that's from the troubleshooting we were doing earlier this week so I cleared the codes and we will see if it comes back.
 
MisterRoy said:
...Also, I had a U code about not being able to communicate with my fuel pump. Not sure if that's from the troubleshooting we were doing earlier this week so I cleared the codes and we will see if it comes back.
Click to expand...

Actually, it is a communications problem with the fuel pump driver electronics, which are in the REM. The fuel pump itself is just a "dumb" motor.
 
joegr said:
Actually, it is a communications problem with the fuel pump driver electronics, which are in the REM. The fuel pump itself is just a "dumb" motor.
Click to expand...
Thank you. I will see if it comes back.

As far as fuel pressure, how do I know if it's low? Is it fair to compare it to the output from TooManyToys? Different cars, different environments, etc.
 
MisterRoy said:
Thank you. I will see if it comes back.

As far as fuel pressure, how do I know if it's low? Is it fair to compare it to the output from TooManyToys? Different cars, different environments, etc.
Click to expand...

I think you'd need to compare it to the MAP. As to if it's actually low, I'd look at the long term fuel trims.
 
The majority of the time mine stays in the mid 50’s range without much variation to map as seen a few post up. Today I had a 40 mile highway round trip so I grabbed some more images. I tightened up the min-max levels for the fuel pressure.

This is a taking off from a stoplight accelerating up to 40mph.


CB45E98A-A838-4AE1-948D-EF198E03D2CC.png



Later running at 65, level ground.


049F76A1-6801-4763-8EBF-3370C95B203F.png



Accelerating around traffic, 65.

71DD7C4F-5BEE-4235-AFFF-A7ACA83BFD4A.png



This typically happens coming off a Parkway with coast down on an exit ramp, fuel pressure spikes up, then recovers. Accelerated as it was a yield, not a stop.


9E95A643-6C9F-441B-854D-EB0DA22D5CF8.png



And then sometimes there is this. After the above I shut down and went into a store. Driving after restart pressure can be a little higher and it tracks with map, just as Joe stated. It will do this until another shutdown.


7E741C61-A69C-4341-B603-C27F57BF1F8D.png




Once in the driveway at idle in neutral the pressure graph is pretty steady.

4ADF85EC-E7B8-43ED-B025-29A49F4B4A75.png
 
So it seems that my pressure acts the same way (consistent, may spike when slowing) but it is a LOT lower than yours.

I will just have to keep an eye in it.
 
What I don’t know is if your Gen1 (I believe that’s what you have) has a different spec then my ‘03.
 
TooManyToys said:
What I don’t know is if your Gen1 (I believe that’s what you have) has a different spec then my ‘03.
Click to expand...

It seems like it might. I wouldn't be surprised if the air assist injectors that the 1st gen uses, need different fuel pressures.
 
I bought the 5-year alldata subscription. It says 39-65psi. Mine seems to be just on the edge when running normal. Does anyone else on a gen 1 know what their normal operating fuel pressure psi is?

Thank you!
 
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