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Rex-I/Regina won't start engine

84B23F

84B23F

Well-known member
Joined
Feb 11, 2008
Location
Kansas, USA
Long story short...if fuel pump works when key is switch on, but engine does not fire up, then try this test

1. Regina Control Test (Key Switch On)
Cable - Select Regina position 2 on the diagnostic socket
Depress button three times - 3 seconds per depression.

If injectors are heard buzzing, cold start valve heard/felt, idle valve felt/heard, and auxiliary relay clicking, then replace the Crank Position Sensor with a Bougicord 271949.

Don't buy a cheap aftermarket CPS...mine lasted for several months, and shot craps.
 
My pump worked just fine.
Buzzed when priming, buzzed when jumpered to run continuously.

The stupid plastic tooth on the pump housing let go, the bracket slid up, the line slid out of the pulsation damper, fuel presure dropped to zero, and I coasted to the side of the road. Merry freaking Xmas!

No amount of CPS purchases would have helped, regardless of brand.
Just sayin' :)

https://forums.turbobricks.com/showthread.php?t=352310




<img src="https://drive.google.com/uc?id=1TObFaQxlZbV3xZ6emSwxpIgiZe4r-gIF" width=600></a>
 
84B23F said:
I indicated "if fuel pump works," which means a pressure test was done.
Click to expand...

It doesn't mean anything in the real world. People hear the pump and ASSume it is actually making pressure. If you actually put a gage on the system, what was the pumping pressure and rest pressure?
 
2manyturbos said:
pumping pressure and rest pressure?
Click to expand...

Ignition Switch On - Bzzzz...full pressure

Ignition Switch Start - Pressure drops... (Spark plugs were removed from head, and a ground wire was hooked to all sparks so that sparks could be observed)

Regina was not getting CPS signal, which Rex-I (pin 17) hands off to Regina (pin 1); CPS was sending pulses to Rex-I, which was activating Ignition Control Module, which charges coil, and spark plugs were lit up...but since Regina was not getting CPS pulses from Rex, Regina will not activate fuel pump relay.

Several month old aftermarket CPS....my hunch, it was not emitting a full voltage/current...just enough to make Rex happy.
 
That’s exactly my point. That isn’t a test of anything. Buzz equals fuel pressure, since when? I have replaced plenty of fuel pumps that “buzz” and make a whole 3 to 5 psi which is not even enough to make injectors fire.
 
2manyturbos said:
my point
Click to expand...

I was using an oscilloscope at ICM (Ignition Control Module) and a fuel pressure gauge. Your point is understood, but a dead fuel pump is not a working fuel pump.

Old school, does it have fuel, and does it have spark; mine had spark, but no fuel within cylinders.
 
I think his point was that in your initial post, you didn't include that pressure gauge was used to confirm line/regulated pressure when pump was activated - that is the relevant piece to include, as some may take it that buzz from pump = pressure....
 
lookforjoe said:
I think his point was that in your initial post, you didn't include that pressure gauge was used to confirm line/regulated pressure when pump was activated - that is the relevant piece to include, as some may take it that buzz from pump = pressure....
Click to expand...

Exactly. I see way too many posts with cars that won't run where the assumption is, hear a whine = adequate fuel pressure. Newbies to fuel injection trouble shooting don't realize how important pressures are. Especially with the antiquated K-jet system.

Anyway, OP, I'm glad you figured out what the problem was.
 
lookforjoe said:
I think his point was ....
Click to expand...

I did state a proviso - "Long story short..."

Addendum - Old and new CPS can shoot craps, but my understanding for Rex-I/Regina, either both ECUs can be inactive, or just Regina. Again, I had a new aftermarket CPS that failed within several months...get the real thing: Bougicord 271949
 
There could have been an open wire between the connector and the ECM.

What is the resistance on the old and new sensor?

Edit- I see you had spark. That rules out an open circuit on the sensor.
 
Last edited:
ZVOLV said:
There could have been....
Click to expand...

In beginning post, I indicated "Long story short..."

I let 940 sit for three months, with a few tests during this time frame.

For Rex-I/Regina, a weak CPS output can throw a curve ball, with Regina not working, but Regina is just waiting for Rex to send his modified CPS signal. Fuel pump would energize with key switched to on position, which is what Regina does, but pump was not powered when starter was rotating. Regina won't engage pump relay until she sees modified CPS signal.

Replacing an older CPS, which I did, is a good maintenance practice, but the new aftermarket CPS was not producing enough voltage/current after several months. I could see the spike pattern on oscilloscope, but this was not needed since I could see all spark plugs firing. I could have hooked up my automotive volt meter to verify voltage amount, but there was no need after I installed a new CPS.

I flipped Rex/Regina ECUs...no change, but diagnostic check indicated they were OK
 
84B23F said:
In beginning post, I indicated "Long story short..."
Click to expand...

Giggle Transylvation:

"... I left out 90% of my troubleshooting information, and it took 14 posts of questions/suggestions/answers to *finally* explain that my no-start fix took more than a buzzing pump and some clicking relays to recommend replacing the CPS. Maybe I should have made the initial story not quite as short?"

That about sum it up? :-P :neener:
 
Yup. I take issue with the assumption the brand of sensor is relevant. Those sensors are not easy to make. My experience includes more trouble with expensive new Bougicord/Electrofil sensors than with $12 aftermarket purchases, but I realize that doesn't mean much either. I'd like to see proof they aren't all made by the same mfr and in necessarily short runs, given the design is many years out of new car production quantities.

The other trouble with recently replaced sensors occurs where the connector terminals in the harness end push back or corrode. Short stories!
 
MasterBlaster said:
Giggle Transylvation:

That about sum it up? :-P :neener:
Click to expand...

There's more...since beginning days of CPSs, mechanics have thrown unneeded parts at the "problem," which consumers had to pay for. In one case, a young couple paid about 1 grand, when the fix was about $30 for a CPS, and this "mechanic" had that fancy Snap-On diagnostic equipment.

On older vehicles I have worked on, there is no CPS diagnostic code.
 
cleanflametrap said:
I'd like to see proof they aren't all made by the same mfr
Click to expand...

Camshaft and Crankshaft Position Sensors detect camshaft and crankshaft rotation during one engine-combustion cycle. DENSO produces both Magnetic Resistant Element (MRE) type and Magnetic Pick-Up (MPU) type sensors.
...
...
DENSO uses a Polyphenylene Sulfide resin coating over the molded IC chip and cylindrical magnet for greater strength and superior resistance to substances like fuel, engine oil and emission byproducts.
..
The molded IC chip is installed inside a cylindrical magnet so it is positioned closer to the gears that rotate with the cam or crank shaft ? this design is almost 10 times more sensitive than Hall element type sensors.

https://www.densoautoparts.com/engine-management-sensors-camshaft-crankshaft-position-sensors
 
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