'82 924 Fuel pressure specs????

[rksmotorsports]

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I need the fuel pressure specs for my 924.

Specifically, I need to know what the psi is at the fuel dist on the feed side.

I have my fuel pump running off of a switch w/shut-off rather than via ignition/key because I have begun to modify it for racing {ie:gutting, roll cage, switch panel/switches for fuel, ignit, fans, etc.}

I have a supply-side adjustable fuel regulator that I am going to install and I need to know what psi it should be set at.

I've looked at several forums and not been able to find an answer....
Thanks all!

[rksmotorsports]

Mods.....sorry for the double post...........oops!

[924RACR]

You should not have a pressure regulator there, and don't add one. What leads you to want to install one?

There's already one in the fuel distributor. I have trouble believing there's very many out there rated for 5bar.

If anything, you should install it in place of the control pressure valve (aka warm-up regulator), to have manual control of the mixture - but only if you have an EGT to monitor mixture.

What class/group are you running with, etc?

[rksmotorsports]

I run in a Spectator class at Lanier Nat'l Speedway {.375 circle track} against everything from Cavaliers to 5.0 stangs and whatever else anyone brings.
As for the regulator......I'm thinking that I may be pushing too many psi to the distributor, causing too much fuel to flow to the injectors.
The prob to be diagnosed is too much fuel/flooding.....especially during start up. there are about 1800 miles on a fresh motor and I've replaced everything from the alternator, coil and wires to fuel pump & filter.
Any help with the diagnosis would be appreciated too. My daily driver is an 84 C4 and most of my knowledge is in Harleys and American iron......the 924 has been an experience, to say the least!
BTW.....I'm waiting on a starter right now, so I can't try any suggestions immediately.....oh, and I do have a hotstart switch also....
Thanks

[924RACR]

In order to test the fuel pressures, you need a CIS-specific fuel pressure gauge. Not sure if your C4 has CIS? Anywho, if those are NFG (no good), you'd need to either adjust the shims in the fuel distributor to change system (supply) pressure, or replace your warm-up regulator (WUR) if the control pressure is bad. Sounds like you're not so familiar with CIS, so probably don't have the gauge setup... can be found online (from a Bimmer place, BMP Designs I think) for around $80.

You might even be better off trying to hook up w/ 924 guys in your area via 924board.org - where are you at? If there's one in the area who has the gauges, that'd be invaluable. Also a great source to recruit crew!!

If you're having flooding/running rich problems - I'd be suspicious of your mixture adjustment and WUR. Have you tried adjusting the mixture yet? Expecially after all that tune up stuff? What have you got in the way of manuals? It would be wise to check for vacuum leaks too, make sure that's all squared away - CIS engines HATE vacuum leaks.

On CIS, mixture is affected by base setting (which functions as an offset across the curve) and by the control pressure. Control pressure is regulated by the WUR, aka the Control Pressure Regulator (which also richens the mixture for cold-start). Usually when the WUR fails, it fails full-open allowing control pressure to equal system pressure. Since system pressure is higher than control pressure should be, this results in a leaner mixture than it should be.

This can be compensated by adjusting the base mixture setting, but still you only have the correct mixture at one point in the RPM range.

So you either need to a) get a rebuilt WUR, or b) use the pressure regulator you have, if it is rated for these high pressures, in place of the WUR. That'll require some plumbing, and you'll want (as previously mentioned) an EGT readout in-cockpit as well as a pressure gauge to monitor what you have it set at. Downside is you'll need to mess with it as you warm the car up every time; upside is you'll be able to adjust the mixture on-track.

Replacing the WUR is the easier, and still possibly cheaper, solution.

Hope that helps; feel free to write back if you're looking for more tips, etc... can't exactly say I've ever run a circle track, but I've managed to put 20% of wedge in the car once (inadvertently), so obviously I'm ready!

[924RACR]

I should add - you don't need the motor running to check the fuel system pressures...