HlhnEast

Still chasing my miss so I pulled the vac line to the FPR and it does smell like gas but there is no gas in it. Is this ok?

The miss is intermittent. The car runs crappy for a week then runs fine for a couple of weeks. Once the FPR fails, its gone, no miraculous "healing". It either works or doesnt, correct?

I am still leaning towards a stuck injector but dont want to shell out that money and find out its a lesser part.

Thanks!

MrWillys

I'd think of it as a rubber! Either it breaks, or it doesn't. My thought would be the fuel smell comes from the plenum which is open to the injector. Intermittent just sounds electrical too me!

leesvet

Not necessarily !

The FPR can leak past in several ways. Gas should NEVER be present on the top side of the diaphragm. If it is, EVER, there is a problem and yes, it can be intermittent.
The disc or plunger that seals off the bowl and has the spring as pretension that the vac pulls against, can wear and cause a "seat" to form much like your intake valves in the cyl heads. This seat is basically a ring that forms to be the perfect seal for the round valve/disc. Sometimes this disc or plunger can move a bit, or rotate and this seat is now broken...no seal, so fuel leaks past and can go directly to return, and you get crappy performance because the pressure to the inj has fallen off BUT the gauge will still show its good, and/or the fuel can be lost thru the diaphragm and be pulled into the vac to the plenum where its randomly dispersed.

New diaphrams can go for $50 to $75. The whole FPR IIRC about $100 + for adjustables.

Take it apart and look CLOSELY at the diaphragm edges...ANY tear or wrinkle in the rubber skin renders it junk. Look at the disc seal surface...it should be a nice even circle with no bright spots to indicate that one spot has been rubbing more than others.

HlhnEast

I am leaning towards fueling because I have no trouble codes. I apparently didnt have the FPR hooked up to vacuum so it sat idle for a long time. When I reworked my heads I realized what happened and hooked it back up. That was about 10 months ago.

If the diaphragm was split I could see it failing and that would be that. If what Lee is suggesting is happening, I can see the intermittent nature of my issue and the smell of fuel but none present. Connection to the plenum could also be the cause of the smell as ****** has suggested.

I will take the FPR off and apart this weekend and check on what Lee has suggested. I want to rule out all the lesser cost items before I jump to new Bosch 3s which I need but cant afford this week.

I still dont rule out a coil or ICM yet either. When I did the head work, I cleaned the cap contacts and in 10 months they were seriously carboned up again which I think might suggest a weak coil or screwy ICM. Its about time for a major tune anyway and those items are pretty cheap. I am going to pull the plugs out and look at them as well

Thanks guys!

leesvet

well, I've learned something about caps with carbon burning on the contacts...

the HEI is going to throw a spark. Somewhere.

If the resistance at the plugs or en route is TOO HIGH...it WILL arc at the 1st available place...the cap contacts as the rotor passes.

So, wires on good with liberal wads of silicone grease in the boots to prevent corrosion between contact and post/pins. Plugs that are the correct heat range and not gapped TOO wide...wide gap means its harder to throw that arc...takes more TIME (milliseconds) and more voltage. Voltage is lost as resistance is encountered. These things lead back to the cap.

Follow the path of the spark backwards...starting at the plug gap and work toward the cap. the aluminum cap post are also good for early wearing out...they don't last nearly as long as the brass contacts.

You're exactly right on the fuel symptoms...fuel system is the ONLY system that does not set codes...no sensors or codes for pressures, flow, leak-down etc...

When you d/c the regulator, look at the disc seat very closely and search for a shiny spot that looks like the disc has been sitting on that one place more than the rest...that's the clue that its been leaking past. The darn diaphragm can look fine where it counts, but the edges get that thin rubber coating torn or scratched and it leaks thru. I've got 3 of the things in the tool box that look fine at first glance...but somewhere on the thing there is a tiny defect that lets gas get by. A new one fixed it everytime.

Searching for a stuck injector is gonna be hit & miss too....you gotta get lucky enough to find it when its not burned the plug clean...otherwise the evidence is gone. Mechanically sticky injectors are usually AFU and stay that way. If its electrically shorted that CAN be intermittent....I've had one that would arc to the nearest piece of metal and short out. If that inj was rotated slightly it would not arc and all was well... BUT, if its electrical, that usually means that entire bank goes down...not just one. And if you have the whole left bank stuck open....YOU"LL KNOW IT !

I pumped 2 gallons of gas into my crankcase that way and damn near broke the motor hydro-locking it with raw gas. That 1 shorted inj made the whole bank stick wide open and cranking the engine forced all that fuel past rings and into the case. When it fired,. wet gasoline blew out the exhaust as it struggled to run on the opposite bank that was operating ok...scared the crap outta me and taught me a large lesson too. Never heard of the bank-fired inj before so I was totally ignorant of how the system operated. Got a great education that day ! I actually watched the fuel gauge go from over 1/2 tank to under 1/4 in less than a couple minutes running time in the garage. Amazing how much fuel these injectors CAN spray when they are WFO @ 50 psi.

If you want to try to clean the system, I've had good results with plain 'ol Marvel Mystery oil in the gas... Lucas fuel & inj cleaner (qt bottle 100 gal worth) seems to do a fair job as well.

Good luck !

HlhnEast

Hmmmm, I need to look at the wiring closely as well. Once I stopped at a store about a 1/2 mile from the house and jumped in. When it cranked it sounded out of time almost and when it did fire it was extremely rough and backfiring. I nursed it home and let it sit overnight. Fired it up and it ran fine. Now if it acts up cranking. I let off, wait a few seconds and try again for a smooth start.

Hopefully it will be dry tomorrow and I will start checking some of these things.

Thanks Lee!