2seater

As I mentioned earlier, it was a concern of mine as well, but I have used a couple of different sets with the plastic cap with no issues. I was assured by an injector rebuild place that it would not be a problem either. So far, so good. I would look at them closely for cracks in the caps before installation, but you almost have to crack them to remove them, so I believe they are pretty firmly fastened. I don't believe the plastic cap would do any real damage and likeley just pass straight through the cylinder. In any case, if the cap decides to leave, it will suck the O-ring into the intake and a vacuum leak will result. You will know about it if it fails.

I have used Casper's Electronics in IL several times, but there are several others out there. It's not really a rebuild, since injectors rarely fail. Usually they are cleaned and reverse flushed and a new inlet screen is fitted. They will be returned with either the individual flow rate or a percentage of deviation within the set you sent in. Usually even an old set are within 2%-3% of each other, and most are better. Specializing in automotive interconnect and wiring systems

Yeah, don't remove it. It retains the lower O-ring which will be sucked into the intake manifold under vacuum without it. Old style manifolds actually have a step inside the injector hole which would retain the cap if it cracked but ours are drilled straight through. I was concerned about the lack of a secondary retention feature when using the plastic cap style, but I have had no issues using various styles of injectors. I have 22# Rochester Motec injectors in the car now which only has the O-ring in a machined groove right at the end of the injector body. There are many different styles out there. Coat the O-rings with a light bit of motor oil when inserting into manifold and fuel rail. It will make life much easier. Removing the old ones is usually a bit of a struggle so watch for the O-rings being pulled off when removing. Make sure you remove them if they stick in place. Unless the injectors are physically damaged, the old ones can be sent in to be cleaned and flowed so you have a spare set.

Interesting. The one on the right looks like the stock configuration. If you look closely inside the single large hole, there should be four or five small holes. I have never tried, but I would bet the extended tip is removeable, the same as the plastic cap. The tip/cap on the end simply retains the "O" ring that does the sealing in the intake. I always ASSumed the metal end was part of the injector body so I never fooled with it. I have a few junk injectors that I will try to see if that long metal cap can be removed and possibly be replaced with the plastic style. I guess that is a long winded way of saying I believe the injectors are the same. I suspect the chart in the Stan Weiss site may be in error, and the difference in flow rate is due to a different pressure being used, although I have no evidence of this. Simply raising fuel pressure of the stock injector to 50 psi raises the stock flow rate by 1.3 lb/hr. Edit: Nope, I was wrong, they are not exactly identical. The metal cap on the end of the stock appearing is threaded onto the end of the body. The 4-hole disc is a separate piece retained by the cap. When the cap is removed, the injector is the same length as an old style Bosch (30 years old), which has an exposed pintle. The metal cap won't thread onto the old style, which is smooth but the plastic cap will snap onto the newer style and can retain the multi-hole disc. Not sure what any of this means, but I would certainly want (6) matching injectors. Sorry for the rambling but I find these oddities interesting.

Sounds good. I hope it works out well. As for an image, the one I sent earlier was just right clicked, copied and dropped in. Alternatively, if you click on the "insert image" icon in the toolbar above, it brings up a menu to allow you to choose an image from the computer or a URL to something like Photobucket or others. I, for one, am curious as to how this works out.

If the (5) injectors are the very slim design, they are the type III, which is supposed to be better in many respects. If you watch the video referred to earlier, you will see the yellow colored one is the type III.

Very peculiar. I could see the GM number being the same, if they are equivalent injectors with subtle appearance differences but the actual manufacturer (Bosch) part # should be different? I have more than a dozen of the -901's and they are identical. I agree they should be sent back. Perhaps Bosch did a running change in design but a new part number should be assigned. They have several injectors in the proper flow range, 19# @ 43.5 psi, all with different numbers. Stan Weiss' - Electronic Fuel Injector (EFI) Flow Data Table EDIT: I scrolled down through the injector listing and there is indeed two different flow rates listed with the same part number. Either would work but only with all of them matching. This is very strange. I have used this injector list for years and there was never two listings for this part number. If the rated pressure was different, then the same part number would have a different flow rate, but that isn't the case.

The photo of the injector on the Amazon site looks just like the standard Bosch -901's that came in my '90. Do all injectors look the same externally? GM uses Bosch injectors as standard on many engines, and if they are, the part number is on the plastic part near the electrical connection and will start with 280-. The last three digits, -901, are the standard 19# injector, and does have multiple holes in the business end. You certainly want all injectors to match and oddly enough, Amazon says it has only one left? Maybe it is your missing injector? As far as I know, Delco does not make injectors, although in recent years there are Delphi brand, which is a pencil style (thin body), that is supposed to be an excellent replacement with a better spray pattern and quicker response. GM also used Rochester brand (Motec) which has a very large body. The vast majority are actually Bosch, even ones found in Fords with their part number on it.

Yes, it is still connected to the front manifold only, hence the reason for the odd modification to the rear manifold. Boost is a little lower than I would like at about 4 psi max, but it works seamlessly. No real tuning done, just the stock chip and about 30% larger injectors. Looking for a used Ford pattern .36 A/R turbine housing for a Garrett T3 to spin it harder. It will just max-out the MAF reading at 172 gr/sec

Now that you mention front/rear vs left/right, I realize I was imagining the engine rotated the wrong way. Now it makes perfect sense. Sheeesh.

I seem to remember the front manifold went to a cast manifold on the later model to help with converter light off due to greater heat retention. Hopefully someone with a '91 can confirm. I just looked at those part numbers and the right manifold is the one on the rear? I would have thought that would be listed as the left, as in the engine positioned front to rear like in a rwd? In any case, the '91 rear manifold looks exactly the same as the LN3 except it has no provision for an EGR tube. I did see a reference to two different designs for the front, one with a seperate crossover and a second design with a crossover integrated with the front manifold. For reference purposes, bone stock, the individual ports flow 151-202 cfm @ 28"w.c (or approx. 1 psi of pressure). This is tested as assembled on the engine pulling a vacuum through the rear outlet with an O2 sensor installed. A ported and ceramic coated set I have flowed 196-249 cfm under the same test conditions. Removing that rear restriction really does help potential flow. Modified further as below helps even more.

Photo from the Buick GS Nationals @ Beech Bend Raceway in Bowling Green, KY on saturday 10/20/12. Is this anyone here?

Modern "V" belts are designed to actually tighten slightly when they get hot from slippage, reducing the chance that they will get worse until ultimate failure. I do not know if the ribbed serpentine belts act the same, but I would suspect they do. The tensioner should keep the tension pretty constant in any case, but perhaps it is close to the adjustment limit? I have a Chrysler product that chirps a bit on cold start but goes away in 30 seconds or so. Particularly bad if cool and damp ambiant conditions. Been doing that for over a year but no other issues I can detect. Probably time for a new belt on mine as well.

Agree with Padgett that "some" clearance should be enough. The only possible fly in the ointment is the angle of the strut to the hub mount is adjustable for alignment purposes and may change that clearance slightly. I have not experimented to see how it changes but I know the tilt (camber) of the wheels can be changed where the strut connects to the hub mount.

Hmm, the engine starts under ignition control from the Ignition Control Module/crank sensor combination and then switches over to ignition timing command from the ECM to the Ignition Control Module. The starting sequence also commands the injectors for the initial shot to start. Fuel pressure sounds a tad high, but gauge accuracy may account for a little of that. In any case, that does not appear to be the problem, regulator controls the upper pressure limits, not the pump, as you surmise. I believe one of the three items is turning off the spark and/or injectors when it goes to the run position, or more accurately, not keeping them going. Does the fuel pump run for a couple of seconds when the key is just turned to the run position? I just read Jim's post and the suggestion is a good one (MAF?). In most cases if you suspect a bad sensor, simply taking it out of operation will help pin it down. I wouldn't think it would cause a stall, but we are finding out the "normal" failure mode does not always apply.

Any LN3/vin C engine should work. Possible there may be minor trim items slightly different if from another make, but all original engine fittings could be swapped on. Almost all full size GM fwd cars of that era were powered by the LN3, as well as many midsize.

Interesting and unfortunately expensive for you. Is the O2 back to normal? The bad module explains the spark timing code but the O2 issue, that would be a stretch.

Bummer. I guess unusual things do happen and I, for one, appreciate your posting the actual problem.

Steady 128 on the fuel readings looks more like it is stuck open loop, but I don't think that would cause the dead readings on the O2 circuit. Engine coolant temperature indication? Electronic spark timing , which probably means it is running with low and fixed timing, will kill performance and mileage. What does the spark timing look like? A vacuum gauge would give a better idea of the intake manifold integrity. My guess is the ECM, as it is the common item to all readings/symptoms.

I do not believe there will be bent valves or pushrods if the cam or chain decided to retire. The moderate lift and dished pistons should clear each other, although it will be close on the edge of the dish. Very unusual if that did happen. I have never heard of that happening on one of these engines although as Padgett has reported, cam bearing(s) have had issues. If it has difficulty cranking, at the very least, pull all the spark plugs and the front valve cover. If internal damage was going to happen, it has probably done so, but turning the engine over by hand to observe movement would give a little better feel. Even with the lifters bottomed out, you should see approx. 3/8" of movement at the valve when rolling the engine over. Checking codes and sensors as others have mentioned is a good idea, but I would use caution trying to start the engine if you suspect actual internal engine damage. Check balancer for integrity. Many possibilities unfortunately.

Also for information purposes: just prior to my replacement of the CPS, my car did the same thing a couple of times. I was not driving it at the time, but my brother-in-law was using it to get to my sons wedding (last June). At highway speed he mentioned it seemed to just shut off and then continue as if nothing was wrong. When we left the church after the service, it wouldn't start at all. But when the rollback got there to pick it up, it ran normally. That started a saga trying to find was was wrong which has been detailed before. This sounds somewhat similar but it is peculiar that it does it in a somewhat predictable fashion. It would almost seems it needs to hit a particular temperature or when it goes to closed loop. As Dave mentioned, all parts are getting old and sometimes failures don't follow a normal pattern like a new part would.

Agree with Padgett's suggestion of weak ignition. Usually a whine in the radio is alternator or some sort of shield ground problem. Spark usually has a stacatto sound along with a possible background whine.

A bad MAF may cause all manner of issues. If the signal is bad, it may run better if disconnected. It will still not run properly, but it will tell you if it changes the behavior. Unplug the MAF and start the engine. (you should get a check engine light) See if it acts the same after it warms up. Alternately, you should be able to observe the MAF signal in diagnostics to see if it is out of the expected range or erratic. Typical warm idle MAF reading is in the single digits. The gram per second readout translates directly to air flow so it should increase smoothly as the throttle is opened, similar to the smooth increase in reading from a good Throttle Position Sensor. Typical leaks at the rear corner of the engine would be coolant from the intake manifold gasket to the head, the valve cover gasket (oil) or exhaust from the manifold to head joint, EGR tube connection or the donut gasket at the manifold to exhaust pipe connection. You should be able to hear an exhaust leak. There is no gasket used between the exhaust manifolds and the heads from the factory but they are sold aftermarket. Headgasket, maybe. Would usually be coolant or possibly combustion gasses.

I can see both sides of the (discussion) argument, but I probably line up on the side that just enjoys cars, for the simple pleasure of my own handiwork and something you don't see everyday. I guess I don't have much affinity for the speculator/investor locking stuff away and removing it from it's true purpose. I guess the ultimate for some would be to see them all gone and to own the only one left, but that just seems selfish to me. Maybe I'm in the minority, but I always thought this forum was to help keep these cars on the road and useful, with a smattering of restoration/investment thrown in, but that's just me. Just for context, my first brand new car, ordered from the factory, was a 1975 AMC Pacer. As you can see, my point of view may not be mainstream, but I wish I still had it.

I made something similar of two quart capacity. I bleed the rear brakes first using the first quart and gravity feed only, letting the brake pump do the work. I then pressurize the bleeder and bleed the front brakes as you described. It works well and avoids the dreaded sucking sound when the rear brake reservoir runs dry if you don't have a helper to keep adding fluid as it is pumped through.