dr bob

FWIW, an Ohm meter will tell you whether all the injectors are connected to the harness, if there are shorts to ground etc. Each injector is about 16 Ohms and they are in parallel, so the loop should show 2 Ohms end to end, with no continuity to ground. If the resistance is higher, it means there are injectors not connected. Lower resistance starts to look like shorted wiring.

WallyP

The OP said:
"I have been able to do some testing time permitting. With the car at idle I can feel the injectors click with a long screw driver touching them. There is absolutely no change when I pull the wires off the spark plugs while running. I did this one at a time and cylinders 5-8 gave no response. Pulling the wire off the plug on cylinders 2 & 3 killed the engine, it chugged heavily for a couple seconds and quit. Wire off plugs in cylinders 1 & 4 was not a very noticeable difference, I think it may have ran slightly rougher but not sure. With the fluctuating idle and popping intake it is difficult to tell if it was the cylinders or just fluctuating engine speed.
Yes, the car was sitting prior to this. You think maybe new injectors are in order? Cap and rotors are new. "

So he is telling us that he has spark on all eight and injectors clicking on all eight. If he has 165 PSI on all eight, it gets curiouser and curiouser...

Kevin in Atlanta

Fuel related-if what Wally said above is still true. I'd want to see the fuel pressure at the rail. I wonder about marginal fuel dampeners and vacuum.

rbrtmchl

How old are the coils? I don't see any mention of a recent replacement, so based on the prior advice it sounds like you should consider new.

dr bob

Fuel pressure is pretty consistent side-to-side on our engines. There may be slight differences dynamic with injector opening, but likely so small you'd be hrd pressed to notice anything on a gauge. Not close to enough to give the run symptoms described.

Spark shows up on an inductive light whether or not a spark happens at the plug. Leaky wires, cracked cap or rotor, tracking in the cap, all can drain spark energy enough to avoid actual ignition but still make a field big enough to flash a strobe timing light. Bottom line is to carefully inspect cap, rotor, wires, and try new plugs for sure. If the cap rotor wires are not recently new, try new bits if for no other reason than to eliminate ignition as a possible cause. Worst case is you replace some pm items a little early.

GregBBRD

Yup, that's the problem. Spark, fuel, and compression....it runs!

I guess that just because the injectors click, doesn't mean that they are not plugged up.

I've not heard any mention of what the plugs that get pulled out look like...you'd think that if those cylinders ran for very long without any spark that the plugs would be dripping fuel....

He's still got some "basic" things to check.

SQLGuy

In the very first post he said, "I began pulling plugs and noticed the drivers side bank looked cleaner, and slightly wet."

Flormat

I have pulled the plugs and grounded- I have spark on all cylinders. I disconnected the lead from coil to distributor cap, pulled plugs off the injectors and put a multi meter to the plug- whil,e cranking I get fluctuating readings anywhere from .10 to .5 volts. Surely it should be more like 12? Then I connected a spare injector on the plug and placed it in a small pail. Cranked the engine and it was dry as a bone. This was for cylinders 7,8 and 4 on the other bank, I did not test any others, my garage is blistering hot right now. It also seems I am losing fuel pressure. When I crank the motor after it's been sitting a while it will take a while to start. If I jump the fuel pump relay for a few seconds, replace the relay it will start right up but it still runs like crap. When I remove the plug on the end of the fuel rail very little fuel comes out, it's clearly not under pressure so I either have a bad pump check valve or can an injector get stuck open? I would think if it's been sitting a while an injector would get stuck closed? i don't know if this is related to the problem or if this is in addition to the poor running condition. When I was pulling wires off the plug to try and determine the bad cylinders, after a while I couldn't get it to start- acted like it was flooded. It sounded like it wanted to start but couldn't quite get there. Another thing I noticed, when I cranked it after it had been sitting 24 hours I could not hear the fuel pump while cranking, but after I jump the relay, replace the relay and start it I can here the pump- that doesn't seem normal.
And I did pull the timing covers and use Porkens 32V'er and both cams showed zero degrees on the nose.
Anyone want to buy an '86.5 with an **** load of new parts? I'm getting pretty frustrated.

Flormat

Bob- coils have not been replaced but the plugs show a nice strong spark. I am thinking it is fuel related.

Bill Ball

The pulse is so short, your meter cannot detect it.

I don't understand your test. What fluid would you expect to come out? An injector does not store fuel.

An injector can work fine when the car is running (not stuck open or closed) but leak when the car is off, or, as you said, you may have a bad check valve, or leaky regulator. You really need to temporarily install a fuel pressure gauge if you want to evaluate this. You may be losing fuel pressure rapidly after shutdown, and that can be a problem to sort out, but it's the fuel pressure when running that you need to know.

With flooding the plugs get VERY wet. When this happens you should pull a plug.

No. But for your testing, I would leave the jumper in, forget the relay for a while. I don't mean to leave the jumper in all the time. Just when you are testing for several minutes.
This troubleshooting is difficult work. And it's hard for us to help you remotely. It's like doing remote surgery but without a robot. It would be ideal to find another more experienced 928 owner in your area to look at this directly with you.

Flormat

Bill- Oh my god you're right. I know an injector won't spray unless there if fuel to it, I have absolutely no idea what I was thinking... at it too long I guess.
Fuel pressure with the relay jumped was 36, I will try it with the car running and post the result.

Flormat

I believe I found the problem, now to locate the culprit. Fuel pressure while running is 18psi, 20 at best. It does not bleed off after shut down. The fuel pump and check valve are new although that doesn't mean it isn't the check valve. Pressure regulator and dampers do not leak when vacuum line is removed. I cannot smell any fuel.

Kevin in Atlanta

If you can get your hands on a vacuum pump see if the regulator and dampeners hold vacuum. My fuel regulator is knackered and holds no vacuum - it takes a lot of engine spinning to get it started.

Hilton

I'm pretty sure your car has dual fuel pumps?

It sounds like your in-tank pump has died and is restricting the flow to the external pump - so once there's flow through the injectors, the pressure drops off. With no flow (i.e. car not running) it'll be able to build pressure.

Simple test - disconnect and insulate one ring terminal off the main external fuel pump, and then jumper the fuel pump relay position and go see if you can hear the in-tank pump running.

Bill Ball

OK, at that fuel pressure the injectors will not spray enough fuel to do anything. I gather your year has 2 regulators. Therefore it must have two returns. [EDIT: Wrong!] Clamp them in the rubber section one at a time. No need to clamp hard and risk splitting the hose - just enough to close the lumen. Then BREIFLY run the car. If the pressure rises quite a bit above what you are seeing now, that fuel pressure regulator is bad. If it doesn't rise, clamp both returns. If it rises then, both are bad. If it doesn't rise, then problem is fuel delivery - most likely the pump(s). If you have an intank pump, there will be electrical wires for that pump on the tank outlet. [EDIT: See below - only need to test the one regulator.]