HOrnbrod

It's beginning to look like it could be something other than a fuel problem. There is one more test you can do, a fuel volume test:

The 370 CPS won't play with the Renix flywheel so you will need to machine the 370 bell housing to place the Renix CPS in exactly the same place as it does on your BA-10. Lots of writeups on Pirate and NAXJA - just do a search for NSG 370 CPS. I haven't done this swap but have researched it a little.

That's correct. Can you replace it with your old regulator and pressure test again? Could be the pressure gauge is off.

What did you use for a FPR? P/n?

Does your MJ fit in the doorway? Looks like it's tight with the lights......

Do the below alt voltage drop test to verify. My positive side was fine, but the negative side was dropping a bit over .5V. After adding the extra case ground wire the drop was negligible and made for a more stable dash VM. Image Not Found

:thumbsup:

Si - it sure wouldn't hurt. I ran an extra case ground wire when I swapped in a 136A Nippon Denso alternator. The VM doesn't drop as much as before when running all the lights and motors.

Very cool! Have not seen too many of these in Bama. :yes:

Good info from Jon Kelly: 1) RENIX used a Delco CS-130 alternator, which is internally regulated. 2) RENIX alternators are grounded through the mount, the engine block, and the main ground lead about 2/3 back (it's attached above and behind the distributor, passenger side.) Valve cover seepage often gets into this connection. 3) The RENIX IP voltmeter is a notorious liar. As mentioned, verify that suspect reading with an independent DMM, connect it to the battery. Delco alternators are actually pretty robust, I've used them on Gawd knows how many conversions (SI and CS series) and in myriad industrial setups. I prefer them over just about anything else. However, Point #2 should be particularly noted. If you think you're having ground trouble (a typical cause for "floating voltage at steady-state operation,) I would suggest making a test lead out of 10AWG or maybe 8AWG wire - make it long enough to go from the alternator case to the battery - post. You may use clips on both ends, or you can put a 5/16" or 3/8" ring on one end - there is a boss on the back of the alternator case, drilled & tapped M8-1.25 (use a 20m/m long screw. Using an overlong screw there can bind the rotor - it's a through hole, usually.) If this additional ground settles down your voltage readings, then clean your main ground (since it's also the primary ground for engine management sensors,) and consider making the alternator ground a permanent installation (rings on both ends - a 5/16" or 3/8" will also fit to the battery clamp bolt and most binding posts.) The alternator direct ground may also be run to the stud where the primary ground attaches - but why not just go directly to the battery? Use min. 10AWG wire for a permanent ground (although 6AWG - same as OEM mains - would be preferred. However, you're augmenting an existing ground, not creating one from whole cloth.) Floating output on RENIX is actually a fairly common issue - and often not the alternator's or regulator's fault... As far as a parts house test? Don't bother taking your alternator in - those benches aren't worth a damn (I used to work on them. They check voltage at 1-2A - but it's current that is the critical factor!) The little red roll-around Bear ARBST (common in parts houses) that tests alternators on-vehicle is a bit more effective, since it will actually load the system, but even that is of limited utility. I would suggest finding a local starter/alternator/generator shop and going there - you'll get a better part, and they can actually wring the damned thing out for you and find out what's really doing on (your issue may also be something like "diode ripple," from failing rectifier diodes. The parts house bench can't test for that.) Sure, the small local shop might not offer a "lifetime warranty." But, the best warranty is the one you don't need - and I've never needed a warranty replacement from my local shop. (I recently talked Rod into doing mail-order as well, click here - www.kelleyswip.com/sjg.html. You'd deal with Rod directly, and do note that he keeps banker's hours on the West Coast. But, his work is ROCK SOLID and that more than makes up for the inconvenience...)

I had this symptom on my 91 when I first got it. After much troubleshooting it turned out to be a clogged cat.

The TPS on Renix system MJs and XJs with auto transmissions has two connectors, one for the ECU and one for the TCU. This is the un-used 3-wire connector you are referring to. You need to get the TPS for the auto.

Try running an additional ground wire (min 10 AWG) from an alt case bolt or threaded case hole directly to the negative battery post. IIRC these things ground only through the mount - not the best.

Your Renix has the Delco CS-130 alternator which is internally regulated.

Thanks. The wheel is from a late 70's Buick Century Turbo. They were also found on select Buick Skylarks and Regal GTs from the same era.

^^ No worries there...........

Did you check for fault codes? http://comancheclub.com/topic/28111-reading-obdi-91-and-92-mj-fault-codes/

That's not the issue. My fuel rail leaks down to zero psi about 2-3 minutes after I shut the engine off - most all do. There is a check valve at the fuel pump, and even with a new pump I still leak off all the rail pressure in about 2-3 minutes. If you haven't already, rent a set of gauges from Autozone or similar and test the pressure at the fuel rail Schrader valve port to see what's up. With vacuum hooked up to the regulator and the engine idling you should read ~31psi. Disconnect the vacuum line and pressure should jump up to ~39psi. Then shut off the engine and see how long it takes the pressure to leak down. 3-5 minutes is fine.

Got pics of the Weber system? It "tore up" an AX15 because of torque? Hard to believe. Sure would like to see your dyno numbers...........

How did you determine this? With gauges? It wouldn't run at all with no fuel pressure....

Si. http://comancheclub.com/topic/44668-project-4-seat-mj-killed-in-the-womb/

Yeah, he is a Brit who bought it in Venezuela I think, and shipped it back to the UK. He had a hell of a time registering it in their MOT, but finally got it done. Then he disappeared from here.........

Strongly recommend you run the 24# injectors @ 49psi if you're not already. Sounds like you already have an adjustable FPR (Hesco?). For injectors you can run the stock OBD2 "gray tops" from a 96-99 4.0 (p/n 53030778), or Bosch "Neon" 702's, Volvo 703's, or similar. You don't want it running lean, especially during break-in. Pull a spark plug or two at regular intervals, maybe every 100 miles or so, and inspect to be sure.

Nope. Going to change the image. :yes: Image Not Found

Bo needs to get his tubes bent. Quickly........ :yes: