Hey everyone, I installed new bosch 3 injectors from South Bay. I also installed a BBK adjustable fuel pressure regulator at the same time. The car starts now, so I'm sure it was the old injectors were stuck. The diaphragm in the stock FPR looked perfect, so I reused it.

Now I'm trying to figure out fuel pressure. The car doesn't run right at all, stumbles bad when I give it throttle. Fuel pressure is a solid 44-45 psi running at idle or wot. It never goes lower, even if I remove vacuum from FPR. I have vacuum at the manifold, though I don't know how much, just checked port with finger.
I'm guessing this is making it run rich. It's that possible? The afpr adjuster is backed out to where it's just touching the diaphragm. Will loosening the screw further reduce the pressure?

Does the vacuum increase pressure or reduce? I'm wondering if the Diaphragm could be causing the issue. It looked like new, no holes, still very flexible.

 

Here's the problem with those, I had the Accel one. There's a metal disc in there that's about 1/8" thick that sits on top of the diaphragm spring so the screw has something to turn down against. The disc already exerts a pressure on the spring, without the screw. I bet if you remove the adjustment screw all the way out you won't get the pressure below 44, vac unplugged. If you have the regulator housing off, flip it upside down and put the regulator in there without the disc and you'll see how it lies flat. Put the disc in and it will sit proud. This is why I switched out to the Holley version. The vacuum decreases pressure at idle and low power. When you step on it, the vacuum drops and the pressure increases. Make sure you didn't knock off the vacuum line under the plenum that goes to the brake booster

 

Thanks for the heads up. I will check for vacuum leaks first. A Vac gauge may me a good idea. That little disc did sit proud. I'm thinking either a fitting disc that's flush in the divet or a thick gasket would solve that.

 

I got the fuel pressure regulator sorted. I've got 34psi at idle now, but only 36 at wide open throttle. It does run better now, but still has bad throttle response under 2000 rpm. It idles good, but when you give it throttle, it feels like it's missing. Once it gets over 2000, it seems good. I haven't checked plugs yet. Wires look and feel like new. They are nice axcel silicone wires. It also has a crane fireball ignition. I'm not sure if that would have any issues after 20 years of storage.

 

I was wrong, it isn't running any better. It is the same as before cold. The improvement was fully warmed up. I tried stock ignition and it's the same. Guess it's time to pull plugs and distributor cap. Running out of ideas. In ran perfect when parked 20 years ago. I just don't know what else would fail from age. If the ecu was bad, would the car run at all?

 

I know this is in a service manual somewhere what the fuel pressure should be fulling warmed up to operating temps at normal idle speed with vacuum hose connected to fuel pressure regulator and without it connected and vacuum hose plugged off.

I'm thinking 37/38 PSI vacuum hose connected to FPR.

I'm thinking 42/43.5 PSI with vacuum hose disconnected and plugged.

You should pull your distributor cap and see what it looks like in there. My friend had a super nice 27k mile 1990 Formula 350 that you could eat off top to bottom, inside and out, and under hood. This car still had the assembly line installed sparkplugs, plug wires, coil, cap and rotor button. 100% untouched bone stock car. Ran great for about 5 to 8 minutes then like crap and couldn't get out of its own way. Don't even think it could rev to 2.5k. Turned out it was the janky Rochester Products Multec fuel injectors. But along the way to getting to that diagnostic conclusion we took the distributor cap off and there was a huge heaping handful of fluffy white and green corrosion inside of it.

 

Thanks for the advice. I checked the cap and rotor, they were in good shape. I cleaned the contacts while it was off. Plugs do look crusty, so I'm trying to figure out what plugs to get. I have headers and Crane Hi 6 ignition

 

What is the condition of the pickup coil in the base of the distributor? 20 years of further copper corrosion after it was last parked probably didn't improve it.

 

It was stored inside in the high desert of California, so there's no corrosion on anything. I ordered new plugs and ran a bottle of seafoam thorough the engine since I'm replacing the plugs anyway.