Testing fuel pressure

[94turbocrewcab-lb]

I’m planning on testing my fuel pressure at the filter head. Temp test not permanent..so from what I’ve read, I take the core out of the valve and then slide a hose onto it with clamp..then hose to mechanical fuel gauge. Low pressure right? Like 6-10psi running?

 

[Nero]

That's one way to do it. I used a tire filler and attached a low Psi gauge to it, so I could just press it on momentarily to get the reading, that way you don't have to lose the Schrader valve, worry about repriming, ect...

 

[Cubey]

My RV ran badly at 5-7psi with Holley Red. With the pedal to the floor, it wouldn't go over 55-60. I lowered the pressure with a regulator to roughly 3-5 and now it's fine again. No idea why. If it's not broken, don't fix it.

 

[ROCK HARVEY]

My RV ran badly at 5-7psi with Holley Red. With the pedal to the floor, it wouldn't go over 55-60. I lowered the pressure with a regulator to roughly 3-5 and now it's fine again. No idea why. If it's not broken, don't fix it.

I know higher fuel pressure going into the IP can affect engine timing. If your Holley red was putting out more pressure than the stock lift pump, it was probably advancing your timing too far. The regulator adjustment was a smart move.

 

[Nero]

Isn't stock pressure 5-7psi? If it's running badly at that pressure could it possibly be a bad case pressure regulator on the IP?

 

[Cubey]

Isn't stock pressure 5-7psi? If it's running badly at that pressure could it possibly be a bad case pressure regulator on the IP?

Maximum Free Flow Rate (gph): 30
Maximum Pressure Range (psi): 5.75
Minimum Free Flow Rate (gph): 30
Minimum Pressure Range (psi): 4.5

Source:

Stock Lift Pump specs

Does anyone know what the stock fuel pumps are rated for on our IDIs? Mainly I'm interested in GPM and at what pressure rating that rating is for.

www.oilburners.net

 

[Cubey]

Another source says:

Fuel Pressure (Filter Inlet) 14 kPa (2 psi) @ idle
Fuel Pressure (Filter Outlet) 7 kPa (1 psi) @ 3000 rpm

Edit: actually same source/person, just on another forum.

7.3L IDI Turbo Diesel Engine Performance Specifications - Ford Truck Enthusiasts Forums

Pre-Power Stroke Diesel (7.3L IDI & 6.9L) - 7.3L IDI Turbo Diesel Engine Performance Specifications - 7.3L IDI Turbo Diesel Engine Performance Specifications Engine Model A-185, A-166 Number of Cylinders 8 Configuration OHV V8 Bore 104.39 mm (4.11 inch) Stroke 106.20 mm (4.18 inch) Displacement...

www.ford-trucks.com

 

[gnathv]

If you use a tire pressure gauge (which is fine) to check your fuel pressure, be sure to wrap it in a shop rag so you don’t get a diesel shower.

 

[94turbocrewcab-lb]

So just stick a tire pressure gauge on the filter housing while at idle? Sure going to be hard to read 3psi

 

[Nero]

No not one of those push gauges... I'll snap a picture of what I use when I get home.... Give me an hour or so.

 

[ROCK HARVEY]

When I deleted my fuel heater I plugged a hole with a 1/2npt pipe plug. I’ve thought about installing a small fuel pressure gauge where that plug is, or maybe a sender so I can have a fuel pressure gauge in the cab.

 

[94turbocrewcab-lb]

I need the fuel heater though..-25 is pretty cold

 

[Nero]

Here's what I use.

You must be registered for see images attach

 

[gandalf]

Cubey alluded to a possible point of confusion in his post above. The pressure coming out of the lift pump and into the fuel filter is higher than the pressure coming out of the fuel filter and into the IP. Where you put your gauge depends which of those you want to measure.

 

[gandalf]

I need the fuel heater though..-25 is pretty cold

Where are you on mid-coast Maine? I'll be doing a power run to Stonington in a couple weeks.