Fuel pressure frustration

[Wed Turner]

Just this weekend I installed a new Autometer fuel pressure gauge. I found out that I was only getting about 38 psi of fuel pressure (I have the blue spring fuel pressure upgrade). After talking it over it was decided that I probably had a HFCM that was going out. So I picked up a brand new one from Ford yesterday and installed it last night. After installing the pump, I cycled the key about 4 times and saw the pressure build to about 54 psi before I turned the key over. This was the first time I saw anything above 42. When I started it up, it still had a really ruff idle and was still around 38 psi. I was frustrated. I decided I wanted to take it for a drive. The engine gets way smoother when it warms up and I wanted to see if it was building fuel pressure later on. This is when I realized that I still hadn't hooked up the lights for my new gauge. So it took me about 20 minutes to get that issue remedied. Imagine my surprise when I started up the truck and saw it build to 60 psi. And you could tell it was obviously idling much better. I thought I had fixed her up good. So I let it idle for a while and it does sound much better. I clean up my mess and let it build some heat and hop into the truck. Immediately I notice that anytime I touch the gas pedal the fuel pressure drops fast. Having seen other's fuel pressure gauges, I knew this wasn't right. But I went on my drive and let it build heat. After about 12 minutes of driving everything was good and warmed up. The truck was running smoother and I still had 60 psi when I was at idle. So I decided to give it about 1/2 stab of throttle and see how badly it dipped down. Well it dropped to 30 psi and I immediately let off the throttle. When I did, it only came back to 38 psi. The whole rest of the way home the most I ever saw was 38 psi. It is much steadier at 38 psi then it was at 60 psi. So what's wrong now? I'm guessing from how it runs that I've got a or multiple injectors going out, but is that what's causing my fuel pressure to be so low?

[PSDMikeB]

Others here may have more experience in this, but my first thought would be to replace both fuel filters, Although, I assume you replaced the one in the HFCM since moving an old filter filter to a brand new housing would be stoopid, but you still have to ask...

The next most easy thing to do would be to install a manual gauge and verify at least at idle that the new gauge is working properly. After that you will be looking at checking the fuel lines for leaks and obstructions.

MikeB

[Wed Turner]

There is a brand new filter in the HFCM, it came in there from Ford. The upper filter was replaced less then 500 miles ago. I've checked all the lines from front to back and the are all in good visual condition. I never have and fuel smell or find any puddles under the truck.

[Term3]

Is the upper filter a Ford brand?

[Wed Turner]

Yes. I pulled them out as soon as I got the vehicle home and only use Ford filters for fuel and oil in the vehicle.

[BeXtreme04]

There is a known issue with the little brass cup in the blue spring upgrade kit sticking and causing low pressure... Most people reuse the original cup and their fuel pressure goes up to a steady 65 psi or so. If you still have the original bits I would try that.. Otherwise you might try taking the regulator apart and see if it is sticking and maybe trim it down some


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[2003kingranch]

It almost has to be something in the regulator. Unless you got a new "bad" pump. How do you have the fuel sender for your gauge hooked up? If you have a strictly line then get a mech gauge and hook it up to the "t" who knows your gauge could be messed up.


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[Wed Turner]

I'm pretty sure I didn't keep the original parts of the spring kit. I'll disassemble it tonight and smooth out the body of the brass plunger and put everything back together. The sender is screwed into the adapter on the bowl. I opted not to remote mount the sender. I am going to try and find a 90 degree bend to get it away from the upper radiator hose as well. I've gotchecked a littletime screw init mechanical gauge that I might try, but I don't know if it will clear the spring cup. Thanks for the ideas. I will let you know how it goes tonight.

[sargar]

Hey Wed, I'll look arourd the shop and see if I can find you a used brass cup if you need one. I'm a pack rat and throw nothing away. Now where did I put that pile of 6.0 parts..........

[2003kingranch]

i got piles of 6.0 parts to lol every little piece