Fuel Pressure Regulator Help

cuhud

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Jan 15, 2020
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Alright guys I've been searching the internet for two days now with no luck, so to keep me from banging my head on my desk im hoping someone here can chime in and help me out. So I have a 91 fox with ERG delete- BBK 70mm throttle body- Trickflow Track Heat Intake - RPM Performer Heads- E-cam- bottom end has been rebuilt but dont know the details. So I had to replace my stock MAF due to me damaging it while cleaning it so I came across a deal for a Pro-M 75mm and 24lb injectors and here is my problem. So I changed out the injectors and MAF with no issues, but I wanted to check my fuel pressure, and when I got ready to check it I noticed the fuel pressure reg that is on the stock fuel lines doesn't have a vacuum line running to it, but has a adjustment screw in the top hole. I searched the part numbers on it 1198DAK and had no luck. I also noticed that my intake has only two vacuum lines running off it the PVC and the other running to the fender wall tree, all others are plugged on purpose. It runs fine but i have notice it will run rich at times and has no codes other than the ERG code. Does anyone know if this is a acceptable setup or does it need the vacuum line even with the adjustment screw in it.
 
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John Dirks Jr

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It needs the vacuum line. Thats how it knows the engine is under load. As the vacuum signal drops from the throttle being opened and creating a load, the regulator increases the pressure accordingly to provide extra fuel to meet the demand.

The fuel pressure should be set to specs with the line vacuum disconnected, then reconnect the line after the pressure has been set.
 
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Blown88GT

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The adjustment screw is for setting the static fuel pressure.
When at idle & under vacuum, the fuel pressure drops about 5psi. Therefore, with no vacuum line, it will run rich at idle. Take a pic of the FPR so we can try to
identify it.
I've never seen an FI FPR without a vacuum port.
Vacuum-Pressure.jpg
 

John Dirks Jr

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Looks like an adjustable regulator, but I'm not sure what brand. Hook up a vacuum line to the upper intake. Check the pressure at idle with the line hooked up, and again with the line not hooked up. Report back with the numbers.
 

cuhud

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It does have a small hole, and I did some more looking and it looks like a Accel regulator but can’t find the numbers anywhere. I’m going to hook up a vacuum line this weekend and check the pressure.
 

Blown88GT

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You can test the FPR without starting the engine.
1. Connect a fuel pressure gauge to the schrader valve.
2. Connect a Mity-Vac to the FPR to create a vacuum of 15-20 in-Hg.
3. Grounding one of the contacts (926) on the self-test connector will run the fuel pump continuously when the ignition is on.
4. Create & release vacuum to watch the pressure change while the pump is running. This is easiest way to set the static fuel pressure.
Self-Test Connector.gif
 

Blown88GT

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This feature is hard-wired into the engine harness. Does not use the EEC-IV, still works with any after market ECU.
Came in handy to drain the fuel tank for pump replacement. Remove schrader valve insert, clamp fuel line hose to valve, put other end of hose into 5 gal jerry can, enable pump. Most bad pumps won't supply sufficient pressure for car to run but will still pump when outlet is open ended, i.e. no back pressure.

BTW, put permanent paint mark around #6 (926) & you'll never ground the wrong one which can damage the ECU.
 
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cuhud

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Jan 15, 2020
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I haven’t had a chance to check the fuel pressure yet but I did run a vacuum line to the regulator and Im honestly very surprised how much better it idle and I didn’t smell like gas when I got out of it. Night and day difference I cannot believe a 2$ fix I was missing helped that much.
 
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John Dirks Jr

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When you get to checking the FP, it should be 39psi with the engine idling and the vacuum line disconnected. Once verified or set, reconnect the vacuum line.
 

John Dirks Jr

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Disconnected & plugged.
I think with the line disconnected, plugged or not plugged, the FP reading wont be affected. The only way the FP would be affected is if the voltage at the pump changed way out of spec. With the vacuum leak caused by the disconnected unplugged line, the engine would likely idle a bit higher if anything. That would not cause a voltage drop at the pump.

Disconnected line plugged or not, no difference in my opinion when checking and setting FP on these cars.
 
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Mustang5L5

A little massaging and it went right in
Mod Dude
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Well, you do want to plug the vac line connected to the engine seeing real vacuum

You don’t want a vac leak after all