North American Turbocoupe Organization

Full Version: anyone with an AFPR or fuel pressure gauge, check this out
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well i installed a aeromotive adjustable regulator on my car a couple weeks ago but i didnt have a gauge to read the pressure. so a friend of mine let me borrow his auto meter 1.5" gauge and fitting that screws on to the rail. we played with the pressure and ended up leaving it at 46, thinking this was more then enough. well i took the car to the track and ended up blowing the head gasket, i was baffled, i was running less timing, more fuel and an ic fan, i figured this all added up to a less potential for detonation. at the track it detonated bad but before i could let off the head gasket blew out. i figured i must have had just too much timing and the fact that there was 131k on the engine. but today i stumbled across the real reason i was having problems. i went ou tand bought my own 1.5" gauge so i could give my friend his back, well before i took his off i checked my pressure and it was at 46 static just like i had left it, then i put my new one on, and whatta ya know it read 30 static, i then realized my friends gauge wasnt even reading 0 when it was off the car, it started to make sense, i had set my FP to what i thought was 46psi when it was only 30psi, OUCH! i then set the pressure to 43psi according to the new gauge and took the car for a spin, wow, it runs mint now, no hesitation, detonation or lack of power. im kinda pissed that i lost a head gasket due to a faulty gauge and i missed out on fun ford weekend, but i guess it was good it rained today cause i was gonna go back up and try again, but instead i decided to put my new gauge on. anyhow sorry for the long post but i figured id share my experience with you guys, maybe this is the reason for the other threads on here where people are getting lots of detonation thinkin they are running good FP, everyone check your stuff! a head gasket is bad but a melted piston would be worse. just lookin out for you all.

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1987 Turbo Coupe 5 Speed - 14.528 @ 90.50
-93 Style Black Cobra Wheels w/ 255 45 17s
-2.25 Turn Cobra Rack
-Aeromotive Regulator
-Intercooler Fan
-6AL Box & Two Step
-Cone Mounted on VAM
-BCS Disconnected, 17-18 psi
-Weight Reduction
3318lb Race Weight

[This message has been edited by Turbo Coupe (edited 08-24-2005).]
As far as the Aeromotive goes also: Brett Clow witht he Aeromotive tech department pointed out the problem with my regulator- there was none [Image: biggrin.gif]

My email to him:

To whom it may concern,

I bought an Aeromotive regulator recently from a private seller. It was still wrapped in the OE box and unused. I changed my fuel filter as a precautionary measurement, and installed the reg. I set it to 43 PSI base pressure, snugged the locking nut down, and forgot about it. I later attached a gauge that is permanently mounted to the regulator because my pressure fluctuates. I have a 1 year old Walbro 190 LPH pump. I have checked, and my fuel pressure does increase 1:1 under boost, all the way to 17 PSI. Every time I take the car for a drive, the pressure changes and I have to reset it! This is really frustrating, and I hear of this happening a lot. What causes this to happen, and what can be done to correct it?


This was his reply:

Ryan,

The only time this happens is in my experience is when a liquid filled fuel pressure gauge is employed. I’ve written about this in the FAQ section of our website, under Tech Help. Bottom line, liquid filled gauges are very temperature sensitive and the reading on the gauge reading drops as it warms up, then comes back up as it cools.

If pressure is checked with the gauge warm and found to be lower than when the engine was started (cold), then the regulator is adjusted to make the gauge read higher, later when the gauge is cold the pressure will read high and have to be set back down.

Ultimately, the pressure in the line, as controlled by the regulator, is not changing one bit. When the regulator is reset to make the gauge read the correct setting, the pressure is actually higher than it should be and this will be evident once the gauge is back to ambient temperature.

Check out the FAQ’s for more details and let me know if this doesn’t apply to you.

Brett Clow
Aeromotive Tech Dept
7805 Barton St.
Lenexa, KS 66214
PH: 913-647-7300 ext 109
FX: 913-647-7207


Here were my findings!

I went outside and my gauge was reading 0 PSI. I stuck some ice on it until it got a good amount of condensation on it, indicating it was below ambient temperature. I held ice on the sides and bottom. The gauge went up to around 5 PSI! So I started the car up and set it to 41 w/ vac line disconnected (I want it a little bit rich since I'm running 17 on the stock IHI, IC, and the base timing is at 12* w/ premium mode on).

Took it out for a drive, come back, take off the vac hose and it is now reading like 38ish. I put the ice back on it, it read back up to 41 again! I hope this helps somebody in the future!

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Ryan Harris

88 TC, 5 speed, B&M Ripper Shifter, Walbro 190 LPH, Aeromotive FPR, K&N, 3.73's, 88K miles
Ryan, that is excellent info! I'm going to get new gauges now because all of my FP gauges are liquid-filled. Moderators, PLEASE put this under the FAQs, this information is worth it's weight in gold, or gas!

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Michael Pinto
www.aerobirdmotorsports.com

1988 Med Red/Red leather 5Spd, moonroof, all options, getting a fresh motor, BBK 255lph pump, Kirban AFPR, Cruzin' 35#s, AM IC hoses, Gillis Valve, AM prototype cold-air kit, 2' long open exhaust Wink, Optima
1987 Code 33 Silver-Blue/Charcoal cloth, currently making my lawn look white trash, will soon be a race car
1988 White/Charcoal cloth auto, g/f's car, HL mod, Clarion CD/Stereo
1988 Shadow Blue/Blue cloth 5Spd, going to be a dirt tracker
1988 Cougar LS Med Red/Red cloth, 5.0/auto, moonroof
1988 Silver/red cloth, 5Spd, moonroof
1992 Dk Green SHO 5Spd, feature car, 13.37 , for sale

RIP-1988 Med Red/Charcoal cloth 5Spd, all options, McK kit, spoiler
I have a large (3" diameter) FP gauge that I'm wondering if it is liquid filled or not. It's the type that has a valve that opens to measure volume out of the discharge tube. I went out and looked at it and there is no indication whether it is lguid filled or not.

It has always seemed quite accurate, giving me usually 35 psi at idle and 41 with vacumm line disconnected on a couple of different fords and a chevy with stock FPR's.

I do have a kirban AFPR that I'm putting on soon and would like to be confident if the gauge. Would icing it down and checking if the reading changes be the best test? If it is at 0 PSI I assume that the PSI should increase if liquid filled with the valve closed?
You want to set the pressure when everything is at ambient temperature, for example walk outside in the morning when it is cool out and your car is cold as a rock. Grab your gauge which is not hot OR cold, hook it up and set the pressure.

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Ryan Harris

88 TC, 5 speed, B&M Ripper Shifter, Walbro 190 LPH, Aeromotive FPR, K&N, 3.73's, 88K miles