Fuel Pressure Testing Question

[Sean Maisey]

Today my dad stopped by to help out and we made up a rig to test the fuel pressure now that I have my HPD in-cell pump and regulator installed. (Seemed like a good idea before putting the cell back into the chassis).

Essentially the test rig is a Marshall 0-100psi gauge plugged into the fuel test port supplied by HPD and an AN6 cap on the fuel line just past the HPD supplied inline filter.

To test I plugged the HPD chassis wiring into the bulkhead fitting and jumped the red "Fuel Pump" wire and ground fitting on the harness to the car's battery on the work bench.

Here is the question/issue. The pressure on the gauge is reading 68-69psi. The regulator seems to be functioning as the pump comtinues to run and fuel seems to be cycling back past the regulator into the cell, but this pressure is about 12-3psi higher than what I understand I should be seeing.

I took the assembly out of the cell half a dozen times and removed and reseated the regulator in the housing. I also tried the smaller O ring included in the kit on the bypass side of the regulator, but all that seems to do is cause the pressure to leak down faster once I disconnect power to the pump.

What am I missing? Is the regulator incorrect or miscalibrated? Is it adjustable? Any advice is appreciated.

Thanks,
Sean

Pictures on my blog in a few minutes... http://seanmaisey.blogspot.com

[RussMcB]

Good test. You're right - Much better to find out now than after the cell is installed.

I can't think of any issues with your test procedure, so it sure seems the regulator is not working as designed. Mine wasn't at first, but I did make a mistake assembling mine, and it worked fine after correcting my mistake. Perhaps HPD should srat testing them before shipping.

A thought: How easily can you plumb in an adjustable regular with a return line to the cell? If easy, that has several advantages over a non-adjustable regulator in a difficult-to-service location.

[formulasuper]

Today my dad stopped by to help out and we made up a rig to test the fuel pressure now that I have my HPD in-cell pump and regulator installed. (Seemed like a good idea before putting the cell back into the chassis).

Essentially the test rig is a Marshall 0-100psi gauge plugged into the fuel test port supplied by HPD and an AN6 cap on the fuel line just past the HPD supplied inline filter.

To test I plugged the HPD chassis wiring into the bulkhead fitting and jumped the red "Fuel Pump" wire and ground fitting on the harness to the car's battery on the work bench.

Here is the question/issue. The pressure on the gauge is reading 68-69psi. The regulator seems to be functioning as the pump comtinues to run and fuel seems to be cycling back past the regulator into the cell, but this pressure is about 12-3psi higher than what I understand I should be seeing.

I took the assembly out of the cell half a dozen times and removed and reseated the regulator in the housing. I also tried the smaller O ring included in the kit on the bypass side of the regulator, but all that seems to do is cause the pressure to leak down faster once I disconnect power to the pump.

What am I missing? Is the regulator incorrect or miscalibrated? Is it adjustable? Any advice is appreciated.

Thanks,
Sean

Pictures on my blog in a few minutes... http://seanmaisey.blogspot.com

Sean, are you certain of the accuracy of your fuel gauge?

[RussMcB]

Sean, are you certain of the accuracy of your fuel gauge?

I saw on another forum that it is the same gage Sean's dad and Steve Oseth used to check their Hondas' fuel pressure (and it showed what it should be - around 55 lb.).

[Sean Maisey]

Yep. What Russ said.

[gtomlinson]

Sean,

You want to see somewhere in the 50 psi region for your fit fuel pressure. There have been some suspect pressure regulators distributed and improper installations. Both cause faulty high pressures and the "six" code to occur.

I use a regular (cheap) automotive fuel pressure testing gauge with a bleeding function so that air can be purged from the line. I think it's best to test the fuel after the fuel filter so you take that into account. Your SCCA fuel test port should be in front of the filter.

Having the correct fuel pressure is very important to proper Fit ECU operation. High fuel pressure was the only problem I had this season with my Fit/Swift. After I figured it out my engine problem went away.

[Sean Maisey]

I reconfigured the arrangement of the HPD parts so that the test port is after the filter, and the filter is in the right flow orientation before these tests.

I spent a while last night checking and rechecking. Took the whole thing out of the tank, took the regulator out of the housing cheecked for debris and obstructions, reassembled tested. About 6-7 times all in all.

Still got 68-70psi every time.

Sean

[gtomlinson]

You have a bad pressure "button" (for the lack of a better word). Ask HPD to send you a new one for exchange. The small fuel pressure "button" is the only working part if you get the O-rings properly installed. Use LOTS of lube and slightly chamfer the pressure block orfice edges with emery cloth prior to seating the "button".

I've been were you are...stay with it and get the pressure right. Order a new part.

[Sean Maisey]

HPD sent me a new fuel pressure regulator yesterday. I popped it in when I go home and it was instantly all better. Gauge now reads 56psi as it should.

Thanks to Tom and Julian at HPD for their help!

Sean

visit my FFit conversion blog: http://seanmaisey.blogspot.com

[gtomlinson]

Great news...glad all is well.

As an aside; I just ran my FIT for the first time yesterday since getting it back from HPD with the updated ECU programming. The fuel pressure now reads correctly on my AIM MyChron dash and the motor starts much faster and on less voltage.

I highly recommend FIT owners send in their ECU if you haven't already. The improved starting process alone is worth it.