930 no start- suspect the fuel accumulator...?

[skrufy]

Hello all-

If this has been covered before- sorry, I couldn't find it in the archives, or I didn't ask the question properly to the search engine.....

'77 930- big mistake- DON"T EVER DO THIS!- took it apart years ago-1995- for cosmetic paint, etc- then kids, house remodel(s), kids, school, work, etc got in the way, poor Daddy's Car pushed to the back of the priority list- you know the drill...... car back together, fresh paint/refinish by me( BTW, 3Ms new dry sanding methodology works great...), all new rubber, new dash, new headliner, gutted like a race car then all new soundproofing, re-dye/refinish of factory white leather interior, etc.... fresh plugs, amsoil, fuel filter, adjusted valves, new discs, all new brake fluid, new a/c barrier hoses- basically a very busy winter/spring...... only 51k miles, also, an excellant excuse to buy more tools.....

ran like a top before disassembly, and would routinely run it periodically w/ fresh gas w/ Techron and Stabil- let it run at idle for an hour or so..... would crank right up within a few seconds......

Just put in two new Bosch fuel pumps because I wanted to replace the old ones @ 32 years old, drained/flushed the tank- no rust, sludge or goo at all, a little bit of dirt, etc, cleaned the tank screen, carb cleaned/blew out all the fuel lines- tank to engine w/ no crud/dirt, soaked in Techron/cleaned/blew out the injectors (although I should send them off to get them cleaned somewhere??...)... have had the fuel distributor off- no visible crud, piston moves freely- I DID FIND 4 out of the 6 tiny fuel screens prior to the fuel injector banjo fittings loose and up in the hollow fuel bolts- tapped them gently back into position after cleaning them.... should send the head off to Dale at Jaytan for a rebuild.....32 year old diaphram, o-rings, etc....

well, it ran up to a few month ago, but was so busy with body/paint/interior stuff I didn't bother to fine out why..... so here's what I have: (already checked all the ignition stuff- no problems there, and yes, there is fresh gas in the tank...)

fuel pressure at the fuel distributor- about 2.0 bar- not enough to open up the injectors for gas- about 2.1 needed for that, with system operating pressure 6.0-6.7 bar according to the 930 manual...... I had been suspecting the fuel distributor as the bad guy.... but maybe not.....

fuel pressure before the fuel accumulator- 8-9 bar/pegged in about 1 second, about blew the face off my test gage this afternoon..... I did not check the fuel pressure between the accumulator and the filter as the filter is new and I haven't found any crud anywhere in the fuel system- luckily!

took the fuel accumulator out, shot it w/ carb cleaner, blew it out gently/ gave it the official Ford Motor Company tap test- no crud, etc..... installed it, after cleaning a fuel return line...... still no run- it wants to, but no gas..... the injectors do not whine/screech when the air plate is depressed = not opening.......

Sooooo- I'm assuming that the culprit here is the fuel accumulator, which must also be acting as a fuel pressure regulator??, although I never thought of it that way in a car- flew jets that had hydraulic accumulators in each power system.... the accumulator has a stuck/broken diaphram or other broken internal component restricting the fuel flow?- it's gotta be..... an accumulator is cheaper than a fuel head....( for all you aviation buffs: in the early days of the F15, at low altitude in certain ambient temperature ranges- the engines could/would flame out in full afterburner because the fuel pumps couldn't keep up with the demand.... an F16 in full AB burns about 1.2 gal/second...)

any input/thoughts would be greatly appreciated by all you CIS gurus out there!

Thanks-

Tim
now this gets scary: '68 911 Coupe- 1973-1978, '77S Targa 1978-1986, '79 SC 1985-1988, '77 930 1987-present- where has all the time gone/so many tools yet to buy!?....

[JFairman]

It's easy to unscrew the fuel pressure regulator from the fuel head and check it out for dirt or bad o-ring, spring, etc.
It regulates fuel pressure by returning some to the tank and there are shims under the small spring that adjust that.

It's just to the right of the metal return line on the head and I think it's the only place you use a 16mm wrench on the whole car.

Of course the accumulator may be junk, but try clamping off the rubber section of the return line from the fuel head and see if fuel pressure goes up.