jwillman

I have rebuilt the FD and WUR.

System pressure is 78-80 PSI.

Cold Control Pressure at 88F is 36-37PSI

Warm Control Pressure is 43PSI.

I have a new fuel pump and check valve but static pressure drops to a few PSI pretty quickly and will have to figure that out after getting it running.

When I installed the FD I set the AF screw to closed/ full CCW and with system pressured up have no fuel coming out of the top supply ports going to the injectors. I start to see fuel filling all 8 ports at 13.5 turns CW. I backed AF screw off to 13 turns and when I manually depress the sensor plate fuel begins to flow out of all 8 ports and I get the squeal.

Problem is when all assembled during crank I get a short start and it immediately dies. Too quick to respond to throttle.

I have tried increasing the AF screw in 1/8th turns up to two full turns and same scenario.

Any thoughts on what else to look at?

drooman

couple things:

88f = 31c 36 psi = 2.5 bar




It's a little on the rich side according to the chart... but not way off by any means.

As far as the bleed down, i would figure that out first. it could be bleeding through injectors which would add to the richness. if the bleed down is fast and it happens to be through injectors it means you could be getting air into your injector pipes that will make for hard starting. A little tip about bleed down: the specs in the book are "minimum" requirements. a healthy system will hold more pressure for much longer. best way to check it is to just bypass your pump relay with a jumper (not running) and let the pressures charge up. cut the relay power and look for leaks:

-pinch off the return hose at the fuel gauge sender, this tells you if its leaking past the plunger valve. (common) i wouldn't think this wouldn't be a thing on a rebuilt fuel distributor but I just got a rebuilt unit that had problems so it does happen.
-pinch off the hose near the fuel filter, this tells you if the accumulator or check valve is leaking
-dirty injectors at rest can drip and cause bleed down
-dirty injectors while operating can spray streams and dribbles of fuel and cause rich running

Bleed down does not just mean the holding pressure after a certain amount of minutes.. the system is supposed "stop" flowing when its shut off, hold a specific measure of pressures for some time, and then remain full of fuel indefinitely (not under pressure). when there's a leak in bleed down not only do pressures fail but air can get into the system too.

stormcrow

check your pressure between the FD and WUR. The WUR controls the fuel going out of the FD. When its cold should be around 30 psi. After it warms up it should be around 40 psi. A lower pressure in the WUR allows the AF plste to lift more easy to allow for a more rich mixture when the engine is cold. As the engine warms up the WUR begins to close allowing a leaner mixture and puts more pressure on the AF plate.

jwillman

[QUOTE=drooman;19579079]couple things:

88f = 31c 36 psi = 2.5 bar


As far as the bleed down, i would figure that out first. it could be bleeding through injectors which would add to the richness. if the bleed down is fast and it happens to be through injectors it means you could be getting air into your injector pipes that will make for hard starting. A little tip about bleed down: the specs in the book are "minimum" requirements. a healthy system will hold more pressure for much longer. best way to check it is to just bypass your pump relay with a jumper (not running) and let the pressures charge up. cut the relay power and look for leaks:

-pinch off the return hose at the fuel gauge sender, this tells you if its leaking past the plunger valve. (common) i wouldn't think this wouldn't be a thing on a rebuilt fuel distributor but I just got a rebuilt unit that had problems so it does happen.

The rebuild was DIY using kit bought online .

I had the FD fully closed using the AF set screw and had injector supply lines disconnected at top of FD so I would hopefully not be flooding the cylinders.

With system pressure of about 77PSI. I did notice I was getting fuel in each injector port but it was not flowing out.

I followed your instructions and clamping off the tank return hose at the sender cap when pump was turned off dramatically slowed the pressure drop so that and the fuel in the ports at fully closed appears to be pointing to the FD.

Think I will go with a tested rebuilt.

Any recommendations on vendor?

jwillman

Okay, been quite a journey the last month.

Per advice I tackled the rapid pressure bleed and replaced the fuel accumulator and fuel filter. The old accumulator had deeply rusty fuel inside once removed.

When attempting to pressurize the system with new accumulator and filter the pump would not spin and got hot to the touch. While disconnecting the pump I got some very ugly fuel out of the strainer fuel line to the pump even though I had drained the tank and put in 4 gallons of new fuel a couple of weeks prior. I again drained the tank and pulled out the fuel sender which was rusty and float was frozen - unfixable. Strainer mesh was completely gone.

I removed the tank and after a few days of vinegar and evaporust inside the tank strainer well the strainer unscrewed easily and no spun tank insert.

I cleaned the tank, installed new strainer and fuel level sender, reinstalled tank, installed new pump and put in 5 gallons of no ethanol fuel.

Today I still had the rebuilt FD I purchased out of the car so I connected jumper and ran the pump with a container at the engine supply line to ensure no ugly fuel was left in the lines.

I installed the rebuilt FD and fully closed the AF mix screw. I left the injector supply lines off.

Results are mixed. With system energized I get 75PSI system pressure and leak down is now good so 1 problem fixed.

The bad is the newly rebuilt FD is bubbling fuel out of a couple of ports even with the AF mixture fully closed.

Additionally when I open the test gauge valve to check system pressure at the WUR it still reads 75 psi and is unresponsive to adjustment of the cold pressure post.

Before with my DIY rebuilt FD I had no leaking ports with AF screw fully closed so seems to point to the new rebuilt FD.

I was also able to adjust the WUR I rebuilt to pretty close to tolerances so unsure why I am now seeing 75psi all the time. The cold pressure is unresponsive to tapping the pin in even way deeper than I have ever had it.

Anyone seen this before or have suggestions?

Cymadesign

Plugged filter in the WUR perhaps or could the return from the WUR be blocked somehow? I don't know if it's possible for the return port in the FD to become blocked in a way that would prevent return flow from the WUR.

jwillman

I did pull the WUR off and disassemble. No debris in the input screen.

I had been getting normal readings with the old FD installed and replaced it as I was not maintaining static system pressure and appeared to be the FD bypassing back to the fuel tank.