I didn't block the feed line. The pressure held by using the valve to block the return line. It fellsome but not enough to worry with. I would think at 60 lbs it would leak some back into the tank from the check valve wouldn't it? These things aren't actually closed systems like an AC unit. Once it went 40, after over 20 minutes, it stayed there until I released "some" of the pressure.

But I may check the feed line before I order a new body just cuz.

 

Mike I wish you all the luck in the world solving your dilemma, I know you will,I wish I could help you with this,a little over my head.

 

What do you recommend to use to pinch off the line?

 

I tested mine a few weeks ago and my pressure held rock steady at 46 psi for over an hour, which is when I terminated the test.

I used an Accel fuel pressure gage screwed onto my Schrader valve position with the Schrader valve removed.

Another member posted here recently that he read in a manual that pressure should hold without dropping for at least 1/2 hour.

Jake

 

Mike,
Something to think about:
1.The fuel pumps have fuel flowing through them, and have check valves in the end bell.
2. there is nothing in the FPR body but holes and flat surfaces.
3. if you have 60 PSI, then your fuel pump can meet the 45 PSI necessary to sustain pressure. Your problem is not the pump.
4. If you have fuel leaking, it is either the check valves in the pump or the FPR leaking, or the injectors leaking, since it is a closed system, where else could it go?

There is no leak if it holds 60 with it pinched off with your valve,
But if you take the valve out of the system by opening it, that is the avenue of the leak. Which line did you put the valve in? you did get the valve in the right place, but is it the vent, return, or vapor cannister line?
Check the vapor cannister. When the engine is off, it should only contain vent vapors. When the engine starts, it should purge, and then close. open when off to contain the vapors.
Does your engine seem to run rich for a few seconds?

 

Mike,
You might have read some of my posts and questions on this exact same subject not too long ago. Reading about the parts that you have replaced and the fuel pressure tests that you have done-I can say that I have done ALL of the same things - except installing the shut off valve in the line.

I STILL have the condition of a fast fuel pressure drop although I hesitate to call the condition a problem - because I am finding no performance issues, with the exception of the occasional extended cranking over time before it fires up. This seems to happen when the car is at operating temperature. If I don't get an immediate fire up when I turn the key, if I cycle the key off and crank it over again, it always fires right up.

So, my only issue is the occasional extended crank over time and *knowing* that my fuel pressure is dropping off faster than it should. In my mind, I have isolated the problem to be at the seat in the FPR where the FPR diaphragm disc seals on the seat.

I am pretty sure that replacing the FPR body will be the solution, I just haven't got that **** about the problem - close but not quite!!

If either one of us bites the bullet and changes the FPR body, I bet we will be reporting a fix to the problem. So...which one of is is going to change the FPR body first? I'm looking at OEM non-adjustable FPR's but will likely hold off now till the driving season starts up next year.

 

ECKLERS and maybe TPiS sell OEM regulators.

Jake

 

that's interesting. I've not heard that before but I would think that would be a more accurate test. I never really trusted the valve personally.

 

I'm thinking the same thing unless I just get a wild hair. But there isn't any performance loss and it always starts if I just cycle the pump on a couple times. But when mine is warm, it fires right up.

It's just one of those things that bugs me. I want everything perfect now

Make you a deal, as soon as one of us changes out the FPR body, we report back.

 

I put the valve on the return line and I haven't noticed it ruunning rich at start up, but that doesn't mean it's not. I'll pay better attention and I will check the canister.

Thanks

 

When I did the pinch off tests on my 86 I used a pair of WIDE BLADE pliers SQUEEZED REALLY TIGHTLY.

Now, let me emphasize that; you must SQUEEZE REALLY TIGHTLY. no timidity here.

Should I emphasize that again!?

Any looseness or loss of plier pressure will cause the pressure to immediately drop. GOTTA MAN-UP ON THIS ONE.

Jake

 

Are you using regular pliers? I got a vice grip so I can clamp it and leave it. I don't recall seeing anything with a wide blade. But I'm sure you could put some thin pieces of wood on either side of the hose when you clamp with the vice grip on it.



Looks like I'll need to do more tests. As with the 24# Accel's in my 89. I was running rich. I put in Bosch III's and now I'm running lean.

When you ground out the ALDL, will the fuel pump continuously run? Do you ground it out the same as if you are reading codes? I figure that would be easier than trying to run 12v to the fuel pump relay.

 

If you have the fuel pressure regulator apart yet, try doing this trick.

The Fuel pressure regulator diaphram with the pivoting disc..............

Get some 600 grit, 800 grit, and 1000 grit or 2000 grit Wet n Dry sandpaper. Like the type for wet sanding paint and clearcoats on modern cars.

Find a small sheet of window plane glass or a small Mirror in the house. Dont let the old lady catch you taking it...........

Lay the 600 grit sandpaper on top of the glass on a table.

Put a few drops of water on the sandpaper.

Take your FP Regulator Diaphram and hold it firmly in your free hand.

Just very lightly smooth out the imperfections on the flat pivoting seat. About TEN 6 inch long strokes on the wetted down 600 sandpaper should work them out. Work in only ONE Direction. Dont slide back on forth on the sandpaper. This will keep the Flat pivoting seat TRUE and Right Angle Square on its FACE.

Then Do it all over again with 800 grit wet n dry sandpaper.

Finish up with 1000 Grit and 2000 grit wet n dry sandpaper. 2000 grit can be tough to find unless you go to your local Auto paint Supply Store and purchase it there.

When done, The finish on the Flat Steel Pivoting seat of Your Fuel pressure regulator Diaphram will resemble a highly polished Mirror like surface. You will see your own reflection in it.

Just lightly clean up the matching steel orfice seat in your Fuel Pressure Regulator Body with some 600 Wet n Dry sandpaper. Just take your thumbtip rolled up in the sandpaper and gently roll it on Steel Orfice Seat. Just a couple rotations of your thumb will clean it up and have it shinning brightly.

Reassemble Your TPI system and retest for a Fuel pressure leakdown once again.

I had the same problem of Fuel pressure leaking down on my 1987 Vert when I replaced all my Fuel Injectors with John Banners BOSCH 3's from FIC.

At the same time replacing injectors, I repalced my Fuel pressure regulator diagpram also.

The replacement FP Diaphram had a much rougher finsished surface than my Original GM part did on the Pivoting Seat.

The Original factory finish was Extremely smooth. Blanchard Ground down to around 1 or 2 Micron-RMS Finish.

Replacements have tooling marks like it was made or cut in lathe. Wont seal properly like the Original Production GM Part did.

I had to tear my TPI down again to get to that Fuel pressure Regulator again.

Polished the pivoting Fuel Pressure Face like I described above.

Reassembled............Mysterious Fuel Pressure leakdown solved.

And also my Fuel Pressure Line pressure is Rock Steady now at all speeds and all driving loads unlike before.

The FP Gauge needle bounced around erractically 4 to 6 pounds rapidly,
Could not get a steady reading prior.

I checked with my SNAP ON FUEL PRESSURE GAUGE Taped to my Corvettes Windshield Afterwards to check my Final results driving in town and on Highway at speeds over 100Mph.

Problem(s) solved.

There just isnt much Quality Control left anywhere anymore with the replacement parts we are forced to buy for our C4 Corvettes when needed.

Welcome to the 21st century. Stinks. hate China parts. GM makes nearly all there replacement parts there now...................... And Vintage 1980's and 1990's NOS GM parts for are Corvettes are getting harder to find by the day.

Way back when replacement GM parts were still made in the good old USA.

We actually cared and took real pride in everything we manufactured and sold for replacement parts.

And Especially for a Corvette.

BR

 

I agree I'll try this first before getting a new FPR body.

 

deal! maybe one of us will get good results with an effective polishing job and avoid buying a new FPR body.