My fuel pressure gauge has been reading a max 100psi lately. I'm trying to figure out if it's reading correctly or if the sender is busted. If I unplug the wires from the sender it sends the gauge to 0 so it's not anywhere else in the line. It's an electronic sender reading from the test port on the upper fuel filter bowl. Gauge is a ISSPRO Performax.

It reads 100psi as soon as I turn the key to the ON position. I also changed out the fuel filters (to the newer part #) which had no effect on the pressure reading.

 

You've got fuel system mods, right? What does it read at WOT?

 

No mods to the fuel system. Only a mild street tune. Reads 100 (gauge maxed) at all throttle positions and idle.

 

Sounds like its a bad sender. Might ohm/ check voltage etc. I saw a post similar to yours brian on a different forum it was said it had something to do with the ground. If I find the post ill send you a link. Might be helpful.

 

If the gauge is at max and 100 PSI being the max for the gauge and it goes to 100 psi as soon as the key is turned on I would say the sending unit is shorted.

 

The fuel pump shuts off after 15-20 seconds if you don't start the truck, key on and wait and see if the gauge drops or stays at 100 psi. Most likely a bad sender or gauge.

 

Fellas,
This may be a dumb question. Why would I want to monitor my fuel pressure? I do not have any fuel system mods. Is installing a guage a preventive maintenance measure? If so, i am very interested. What is the benefit knowing fuel pressure.........?
Thanks

 

Jaybird,

The injectors in your engine are very fussy about fuel pressure. It has been proven that fuel pressures, either too low or too high, kill injectors and damage engines. It is becoming very clear that as more trucks get fuel pressure gauges, the fuel pressure issues are much more common than anyone thought. Low pressure predominates. I had 3 stock fuel pressure regulator springs and one of them was new. They all failed to provide adequate pressure under full throttle runs. Low pressure will kill an injector internally. Ford specs a minimum of 45psi at all times. Ford also specifies that the maximum fuel pressure should not exceed 75psi. More pressure than that will cause o ring failure. This allows un-metered fuel into the combustion chamber. If it gets too bad you can hydro-lock the engine. Fuel pressure gauges are right up there with coolant filters and eot/ect gauges or monitors for the most important upgrades you can do for your truck. I use an Edge Insight for most of my monitoring and an ISSPRO EV2 fuel pressure gauge for that parameter.

Regards

 

Thanks for the input. What is generally the cause of high/low pressure? I will definitly put this one on my preventive maintenance mod to do list.....it keeps growing with the more i learn

 

Common culprit is the fuel pressure regulator spring. Easily fixed with either the new kit from Ford or a bb. If you do anything, get a gauge first.

 

I'm glad the message is getting out. I've been screaming this for a long time. I've used a drawstraw and the factory pickup and both cavitate to zero pressure with 7 gallons left in the tank if you make a hard stop. Not all trucks are like this, but many more than people might think.

 

The instructions for my guage state that if you don't ground the unit correctly it will stay at 100 psi. Something to check anyway.

 

I've determined that the gauge sender is bad. The unit is grounded through a central brain or ESP. The other gauges all use the same ground, power, data bus wires so if the ground were bad the others would read bad as well.

Waiting to hear back from the ISSPRO rep on a replacement.

 

Hey Rick, do you happen to have a part# for Ford kit? What does "bb" refer to?
After talking with you last week, and reading this, it makes sense. The O-ring failure would explain why it hydro-locked. I haven't touched the truck since talking with you. If I'm going to get under the hood to pull glowplugs I might as well repair/replace the fuel pressure regulator.

Jeff

 

When I installed my fuel pressure gauge, I didn't have the sender hooked up. I just had power running to the gauge. It would peg at 100 when the key was on. Once I plugged in the sender, and hooked up the unit to the test port on the fuel filter bowl, it started reading right. Maybe ur sender isn't plugged in all the way, or like previously stated, it's bad