0mattkeller0

Hey everyone, new member here. I recently came across an opportunity to bring an 86 5000s, FWD 5-speed NA, back to life.. I normally wouldn't consider something like this that has been sitting for 20+ years, but it is very very clean. The car has been held in heated storage for 20 years and has 89,000 on the clock. The downside is that it had fuel in the system the whole time, turning the CIS into a nightmare.

I am fairly mechanically inclined and decent diagnostician, so I figured it would be worth a shot, but CIS is something I am new to. I have scoured all of the no start threads on these systems, but I seem to have a combination of symptoms that doesn't line up with what has been cleared up so far. I have read up on the system as much as I can, using resources here, and SJMautotechnik, but am stumped at this point. I am trying to get the car to at least limp to life before I start spending too much on new parts. Here is what I have done so far:

-Diagnosed no fuel pressure - dropped the tank and cleaned out rust/gunk. Pulled the fuel pump, confirmed it was seized and replaced with an OEM new old stock. It looks like there was a check valve on top of the pump? I cleaned this best I could and reinstalled. After this, I was able to start the car for the first time. It came to life with a little help from the pedal and managed to idle for a bit, roughly, before I had to kill it due to exhaust smoke inside. This was the only time I got it to start and run for more than a second or two, so far. Just enough to give me some hope....

-Have not been able to get it started since. The best case is after sitting for several hours, it will fire for a brief second, I suspect from the cold start injector, but dies immediately. I then found that the plunger was stuck up in the distributor. I pulled the FD and took the plunger out and cleaned. It will now drop down to a rest point from its own weight. Still was not able to get a start other than the brief cold start injector combustion.

- I cracked open an injector connection at the FD after cranking and found very little pressure. I leaned toward bad o-rings in the FD and was right. I unfortunately had to open the FD and separate the halves. The diaphragm was in one piece with no tears (probably should be replaced eventually), all the springs and cups were good too, but the small o-rings around the spring clips on the tower part were dust. I replaced those. Now I get pressure to injectors, but in a strange way. Just from the cranking, it looks like there is no fuel being sprayed, but fuel will spray when it fires from the cold start injector. To me this is a good thing, as the injectors get fuel when vacuum is pulled from actual combustion. But is there supposed to be fuel spray just from cranking? Is that enough vacuum without firing?

- Next test, and not sure if was useful, was to jump the fuel relay to see how the injectors behaved. This caused more questions than answers. As soon as I jump the relay, with no key, I immediately get a hissing sound from what took me a second to trace back as the injectors letting gas out. I thought this was odd as I figured it would at least require a key in the ignition? Sure enough in the 30 seconds of hissing, the engine was flooded with gas. I am not sure what to think about this....cranking produces no fuel spray until actual combustion vacuum is pulled, but jumping the relay sprays fuel?

- At this point, I am confused as to what to look into next. I have looked for vacuum leaks and have not found anything obvious. I can still feel the slight resistance from the plunger when the CIS vacuum plate is lifted, so the plunger should be ok? The behavior from jumping the relay, without a key in the ignition really threw me off, and I have not been able to find anyone else with this happen in searching so far....Is there an idle pressure controller that is faulty that I am missing? I think that is the electronic sensor on the side of the FD, but I don't quite know for sure what it should be doing. Should the injectors be spraying from cranking alone, or do they need combustion vacuum to be opened up like I have noted due to the cold start injector?

If anyone has any ideas as what I could look into as a culprit, I would really appreciate the help. The car is too clean to scrap/part out and getting it to rough idle with just a pump gave me some hope. Maybe 20 years is too long after all but I sure hope not.

Matt

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treehunter

Matt, wow sweet find and sounds worthwhile but you’ve got some work ahead of you cleaning and replacing hoses, seals etc.

The injectors do not run off engine vacuum.

More than likely all the crud in the fuel lines has been pushed to the end of the line and the injectors are gummed up.

warm-up regulators are problematic as well but you did get it running so I’d remove the injectors and send them out for professional cleaning or buy new.

Mechanically the engines are bulletproof, its always some weird electrical or fuelling issue that needs sorting.

You’ve found the SJM site which is an incredible knowledgebase now go find a Bentley Repair manual for it and you’re on your way to success.
Have fun with it👍
Mike

0mattkeller0

Hey thanks for getting back to me. Thats what I expected, just wanted to have a good idea that it was the injectors so I don't go down the wrong path. Sorry, poor choice of words with the injectors running off vacuum, what I meant to say is should the injectors be sending fuel during cranking or only actual combustion? How much air flow across the sensor plate will open them up? Just thought it was interesting that they are open and spraying when I power the fuel pump, but in an actual test with the relay in, the front one only sprayed from combustion and not cranking.

Either way, I hope to get them all pulled and soaking, then a backflush. I appreciate the help!

treehunter

CIS is constant fuel injection

the best part here is you did get it running so just keep going down the line and you will get there

then a tbelt asap

could always spray a can of starter fluid in there and see what happens…

0mattkeller0

I had some time this week to tinker and haven’t found any smoking guns yet. I removed the injectors and injector lines and cleaned them, confirmed they have a good spray pattern. I also pulled the cold start injector as I thought it may be stuck open. Tested it with a 12v power source and it clicks on and off. I thought this may be the problem as it turns out the cold start injector is what flooded the cylinders when I jumped the fuel pump relay. Whenever I jump the relay, the cold start injector immediately starts spraying, key in ignition or not. It sprays with a ton of pressure. I put plastic bottles on every line including the cold start injector, and when I jump the relay, the cold start bottle will fill in about 10 seconds and the others are empty with injectors installed. Is this expected behavior? If I can continually crank the car, the cold start injector flow will just barely get the car to fire, but not idle on its own. Almost like the injectors are not getting pressure. When I lift the distributor sensor plate, I can feel pressure from the plunger. I cannot do this test with the relay jumped to see if the injectors spray because the cold start injector will spray wide open, whether it’s plugged in or not. Any ideas?

treehunter

Cold start injector is only meant to briefly pulse to literally aid with cold starts. Jumping the fp relay is not the way forward.

You have either a fuel pressure issue or your fuel distributor settings are off…and or the fuel distributor is toast.

Then again you did get it to run and idle initially so what has changed since then?

0mattkeller0

The only reason I was hoping to jump the relay is to check the spray pattern/pressure on the injectors, but the flow from the cold start injector makes it difficult. I am also concerned that the cold start injector is not fully closing. When I did get it started, there was quite a bit of white smoke coming from the exhaust, I would guess it has water, dust, debris to burn through but am not sure if it was also running really rich due to a bad cold start injector.

Since I got it running, the only thing I did was drop the tank and clean it out well. After reinstalling the tank, I couldn't get it to start again. I found that the fuel distributor plunger was stuck up, so I cleaned it out and have since done the rest of the investigative work. The plunger being stuck up may have also been the reason for the rich smoke while it was running the first time.

0mattkeller0

I had some time today to run a couple more quick tests. The first thing was cleaning the cold start injector made a difference. I do think it was stuck open previously, when I jumped the relay it would immediately spray when unplugged. After cleaning, jumping the relay will only fire the injectors and not the CSV. Other note, the injector spray pattern looks good both when jumping the relay and when cranking with the relay installed.

One point of confusion is on the spray pressure of the injectors. I jumped the relay and took the intake manifold duct off to expose the distributor air metering plate. When I trigger the pump, the injector spray is constant whether the plate is resting or pulled up against the plunger. I feel the resistance of the plunger when the plate is pulled up about half of an inch, and it goes away when lowered. I guess I expected the spray of the injectors to change either audibly or visually when in plastic bottles? Should this be the case? Another note is the injectors seem to spray with this same amount of power when cranking too. From what I’ve seen, I think it should be a very faint spray and when the sensor plate is lifted it should be similar to where it’s spraying at now…

The other thing I noticed today is that the ISV is humming when the key is in ignition. I am guessing that means it’s seized up so I took it off and will clean tonight. Any tests I should run on this to make sure it is functional? If I shake the isv a bit it sounds like there are free parts in it, but the humming is pretty loud. From what I understand, this shouldn’t keep the car from starting either, but I could be wrong.

0mattkeller0

Here is a video that makes me suspicious on the jumped relay causing the injectors to spray right away. In this video at about 6 minutes, the gent jumps his relay with a switch (so do I) and the injectors don’t spray until he lifts the sensor plate. Mine go crazy without the sensor plate being touched.


Two videos I took show me jumping the relay and checking the spray in each bottle. Each time the injectors spray, I momentarily jump the relay. Then I checked by cranking the car with the relay installed and the intake manifold boot taken off, the sensor plate shouldn’t have moved from cranking then. You can see the cranking makes all injectors spray with the same heavy pressure.

0mattkeller0

So in doing some general CIS reading and something that I haven’t come across much, at least in relation to the 5000/200, is the fuel distributor gland nut that seats the plunger. Thinking back to taking the plunger apart, I didn’t I adjusted the glad nut way too far into the distributor body. I will check that tomorrow, that would explain the immediate heavy injector spray…

I am guessing the ISV humming is unrelated, but still should be cleaned. Any input on tests or checks on this once clean would be appreciated.