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Testing fuel pump pressure...umm, what am I doing wrong?
Posted by: brocklanders ()
Date: June 15, 2010 04:28PM

Well here's another reason I apparently should be banned from working on cars...I can't seem to work TWO fuel pressure test kits.
They are:

Equus fuel pressure

Vacuum/ fuel tester

Holley FPR

So this is on an electric fuel pump, leading to a 1-4 psi Holley fuel pressure regulator all mounted in the engine bay. I'm trying to diagnose some funky stalling issues and never really trusted the "Factory setting" of 2 psi on the FPR so I decided I really needed to make an assumption a fact. I used the 2nd link Fuel/Vacuum tester, hooked it all tight as a drum and activated the pump.
Pretty much got rising guage that maxed at 6-7 psi, and no matter how I adjusted the FPR it never made a difference. I tried tightening it down tight, same. TAKING THE ADJUSTER COMPLETELY OUT...same reading. I released the pressure a few times since it was just air, no fuel...finally got fuel at the gauge...same thing.

I tried the 1st link test kit (which isn't really well suited for these pressures as it's a 0-100...not very accurate for 1-4 no?

I'm obviously doing it wrong..whats the trick here?


As for the issue, the car wants to stall inconsistently if warm or cold when you step on it from a dead stop. all linkages are dead on, carbs are set perfectly, timing, dwell etc..bang on.....

1968 Corvair 500 coupe 140 4 spd
Bowmanville, Ontario, Canada


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Re: Testing fuel pump pressure...umm, what am I doing wrong?
Posted by: gnvair ()
Date: June 15, 2010 05:42PM

Have you verified that the bowls are empty or over flowing when it stalls?
It sounds to me like the pressure is causing gas to overflow out the vents.
I have posted pics before of my gauge set up. I use a 4 way brass tee as found on the earlies with the gas heater and the 68-69's. I installed a Holley fuel pressure gauge in the extra port.
I have 2 pics. 1 of the Holley fuel pressure regulator and gauge when the car still had the YH carb

and here is with the Rochesters and the 4 way tee.

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Re: Testing fuel pump pressure...umm, what am I doing wrong?
Posted by: Curtis ()
Date: June 15, 2010 06:13PM

Gnvair, how much was your setup and where did you get it? I am going to do the exact same thing on mine after the convention (not enough time before) and this info would be helpful.


Thanks!

Curtis

64 Spyder Convertible
Milwaukee, Wi

Former Corvairs
62 Monza 900 Coupe (102/4)
64 Monza 900 Covertible (110/PG)
65 Monza Coupe (110/PG)
66 Monza Coupe (110/PG)
66 Monza Sedan (110/PG)

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Re: Testing fuel pump pressure...umm, what am I doing wrong?
Posted by: lgoodwin ()
Date: June 15, 2010 06:51PM

Brock, don't beat yourself up. You're just experiencing "a series of unfortunate events" (have you ever seen that movie? Jim Carrey drives a Tatra!).

Do you have a picture that shows it all hooked up?
The only reasons I can think of for no difference in output PSI are
a) You have the guage BEFORE the regulator
OR
b) Regulator is not working at all

It might be a good idea to test the regulator by itself (off the car). Maybe it's sticking open?

As gnvair pointed out, you may have a problem in one or both carburetors, You should try to verify that they are working properly. Do you have another Corvair handy that you can test them on?

Another thought: You have a Powerglide, NOT a manual trans, right? Have you verified that the stalling has nothing to do with that? If it stalls with the trans in neutral, I guess this would rule that out as a possible cause...



<table align='center' width='0'>
<tr>
<td><img src='[www.automation-scs.com]; alt='1962 Corvair 900 sedan' width='190' /></td>
<td><img src='[corvaircenter.com]; alt='1967 Corvair Monza 140/4-speed' width='190' /></td>
<td><img src='[corvaircenter.com]; alt='1968 Corvair 500 coupe' width='190' /></td>
<td><img src='[www.automation-scs.com]; alt='1983 Mexican Mustang 5.0' width='190' /></td>
<td><a href='[www.automation-scs.com&]; target='_blank'></a></td>
</tr>
<tr>
<td align='center'><font size='1'>1962 900 sedan needs a home</font></td>
<td align='center'><font size='1'>1967 Monza 140/4-spd</font></td>
<td align='center'><font size='1'>1968 500 coupe (now my son's)</font></td>
<td align='center'><font size='1'>1983 Mexican Mustang 5.0</font></td>
</tr>
</table>

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Re: Testing fuel pump pressure...umm, what am I doing wrong?
Posted by: brocklanders ()
Date: June 15, 2010 07:48PM

Definitely have the test kits in the right spot. I have not ruled out the PG. I've been trying to read up on any problems, and only thing I can think of is a vacuum modulator on the side of the PG or the Vac. lines themselves?

I just wanted to 'tick' this FPR as O.K. and move on as I doubt it's the problem, but as with all the rest of the problems, it would be nice to confidently say that area is "taken care of" so to speak and confirmed to be working well.

So I've done the tests properly?

1968 Corvair 500 coupe 140 4 spd
Bowmanville, Ontario, Canada


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Re: Testing fuel pump pressure...umm, what am I doing wrong?
Posted by: kenFL ()
Date: June 16, 2010 05:58AM

I'm a seat of the pants kind of guy. I just hooked up my Holley regulator (I think I have the same one as you) and adjusted it on the engine with it running. IIRC mine too seemed a bit stubborn at first to change its initial "factory" setting but after a few adjustments in and out, I got it at a consistent setting (I'm running at 3.5lbs).

Maybe when using the tester gauge to test it, the fuel pressure regulator doesn't want to react the same as when actual fuel runs through it.

Don't feel bad, I've had the same poor luck with many issues that all seem to be simple enough, but you just keep hitting dead ends that don't make any sense.

Try installing it and adjusting it on the fly.

PS: about the stalling from a standing start; you are sure your accelerator pumps are good, right? Some report premature damage and tears due to the "new" gasoline out there. Just a thought.

Good luck

Ken 1963 Rampside
AKA: Cadillac Ken
[www.kidddarrins.com]

"If you aren't going to do it right, just don't do it" : My Dad, RIP

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Re: Testing fuel pump pressure...umm, what am I doing wrong?
Posted by: Richard ()
Date: June 16, 2010 12:37PM

Were you connecting the gauge, either gauge without using the "T" fitting so the fuel would flow to the carb? A regulator has to be able to bleed off the excess pressure in order for the output pressure to be compared to the spring (adjusted) pressure.

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Re: Testing fuel pump pressure...umm, what am I doing wrong?
Posted by: MattNall ()
Date: June 16, 2010 12:53PM

Brock...as Richard states....

you must measure pressure with a restricted flow only...


Free flow is no good.

Dead Ended is no good


You have 2 carbs...you can use one side's line.....because the other side is connected to a carb..

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Testing fuel pump pressure...umm, what am I doing wrong?
Posted by: brocklanders ()
Date: June 16, 2010 04:02PM

Yup, there it is. It was dead ended from the regulator right to the gauge. Rookie mistake!

thanks....I never cease to amaze even myself.

1968 Corvair 500 coupe 140 4 spd
Bowmanville, Ontario, Canada


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Re: Testing fuel pump pressure...umm, what am I doing wrong?
Posted by: merjas ()
Date: January 08, 2021 04:02AM

gnvair, can you re-post the picture of the 4-way "T" installed w/Rochesters? I'm contemplating the same thing and can't get the picture in the original thread to load when I click on it.
Thanks

Gary Merideth
Windermere Fla
68 Yenko Stinger tribute
89 944S2 racecar
06 C6 Z06

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Re: Testing fuel pump pressure...umm, what am I doing wrong?
Posted by: vairmech ()
Date: January 08, 2021 05:20AM

brocklanders Wrote:
-------------------------------------------------------
Snip---
> Well here's another reason I apparently should be banned from working on
>
> As for the issue, the car wants to stall inconsistently if warm or cold when you step on it from a dead stop. all linkages are dead on, carbs are set perfectly, timing, dwell etc..bang on.....


No one seemed to address this issue. This sounds like a typical accelerator pumps not working. That is not a fuel pressure issue!

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Testing fuel pump pressure...umm, what am I doing wrong?
Posted by: azdave ()
Date: January 08, 2021 06:41AM

vairmech Wrote:
-------------------------------------------------------
> No one seemed to address this issue. This sounds like a typical accelerator pumps not working. That is not a fuel pressure issue!

Agree but it was over 10 years ago that the author asked the question and he hasn't logged in here for over a year. smiling smiley

Dave W. / Gilbert Arizona
65 Corsa 140/4
66 Corsa 140/4
66 Corsa 140/4 w/factory A/C
66 Corsa 455 Toro V8
65 Monza Convertible 110/4
66 Monza Convertible 140/4 A/C
65 Monza 4DR 140/PG w/factory A/C
65 Monza 4DR EJ20T/5



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Re: Testing fuel pump pressure...umm, what am I doing wrong?
Posted by: isucorvair ()
Date: January 08, 2021 03:14PM

I'm pretty sure BrockLanders figured it out.

His car moved on, and he had the 67 Fitch Sprint Sedan he rebuilt after that one (that went to the UK and was in a horrific accident)

Not sure he has Corvairs anymore.


Eric P.
DeWitt, IA

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