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930cabrioboy 05-20-2008 07:13 PM

barn find 930 that wont please
Hello everyone, I am new to this forum and love it already, hope I can get some help.

I lucked out by buying a 1986 930 (poorly stored) last month and this car has been stored for 5+ years. The previous owner emptied the gas tank and ran the car till it stalled.
When I got the car I flushed the oil, lubed the engine back up and began troubleshooting why she wouldn't start...seems to be fuel related?. It now has a full tank, I proceeded to check that I had fuel at the airbox main line, it did. I had no fuel at the hardlines, so I removed and cleaned that whole box and then had fuel at the fuel injector side of the hard lines. but still no fuel in the spark plug chamber(not wet after multiple turning over)---I do have spark if anyone wondered. I then proceeded to remove and clean the mechanical fuel injectors, each were a bit sticky but after soaking in cleaner and blowing 110psi of air through them....they seemed to function normally. but still no fuel in the chamber after removing the plugs to check once it was turned over again several times.

I wondered if anyone can help and if I can easily check the fuel pressure and at what psi it should be at. to me it seems to be a pressure problem and the fuel flows well when not plugged to the injectors?? The pump sounds strong and I tried bypassing fuse #6 to test if it was a dme problem.

Thanks in advance for any and all help....I really want to take my new baby out this summer!


9dreizig 05-20-2008 08:50 PM

First thing to do is check the throttle plate,, with the key on push it down.. Do you hear the fuel pumps running ??.. Often my engine when I pull it won't start till I do that,, almost like a vacuum lock..
Next where are you ?? Might have some of us close by..

A930Rocket 05-21-2008 06:42 AM

And don't forget the pics!

rsrmike 05-21-2008 06:46 AM

The plunger in your fuel distributor is probably stuck as well... good luck. I would find a book about CIS injection and study it well, If your going to sort this out yourself. You will most likely have multiple issues, fuel dist. gummed up, warmp-up regulator or WUR may be clogged up as well. Also, the system pressure regulator in the fuel dist. will most likely need to be cleaned up. Do your homework before you dive too deep, these systems are mildly complicated and very sensitive to trash and mis-handling. Good luck

RarlyL8 05-21-2008 09:55 AM

It wouldn't be a bad idea to flush and clean the entire fuel system. As stated, the small passages in the fuel head are prone to gum up as is the plunger.

crimson ghost 05-21-2008 11:36 AM

Pics please :)

930cabrioboy 05-21-2008 06:51 PM

thanks for the responses, I will get on those pics asap.
The system was cleaned out from the hard line from the filter twards the injector...I have alot of flow, but that doesn't mean enough pressure to open the injector pins. It really seems to be lacking pressure. The plate is not sticky and opens rather well (my days of 1984 volkswagen rabbit gti's are comming back to memory
Is there a location I can place a pressure guage to test the psi of the fuel system/ on. I see a 10mm +- screw (havent actually sized it up yet) beside the upper bowl where the hard lines start..can I place it there and how many psi should I have?

I do here my pumps on, and as I stated in the earlier post, if I remove the hardline at the injector near the valve cover, I get a steady flow (gush) as I put the key on. but it never wets the plug??....I am far from a rocket scientist but it seems to be pressure

thanks again to everyone..all help is good help.

p.s I live in Montreal Canada.....unfortunately far from most you guys....but us Canucks love our porsches!!:D

9dreizig 05-21-2008 06:55 PM

"but us Canucks love our porsches!!" Yes almost as much as we love your strippers, err I mean Mt Treblaunt !!!
I"d pull and injector and see what the flow looks like.. PIA but will answer a question or two.

Hayabusa 05-21-2008 07:43 PM


Originally Posted by 930cabrioboy (Post 3956809)
I live in Montreal Canada..... us Canucks love our porsches!!:D

We also love our hockey! SmileWavy Good luck on your new baby!

wjfk32 05-22-2008 12:03 PM

Same problem. I didn't start my car for 9 years........Dumped the fuel out of the tank. 2 fuel pumps shot. Changed both, fuel accum., injectors, fuel filter, changed oil & filter... Car is running well.


equality72521 05-22-2008 12:07 PM


Originally Posted by wjfk32 (Post 3958197)
Same problem. I didn't start my car for 9 years


How could you go 9 years without starting it?

wjfk32 05-22-2008 12:09 PM

Out of the country. For a long time.....................................

930cabrioboy 05-22-2008 04:48 PM

It may be the injectors, I will start by changing my accumulator and filter.
does anyone know how to clean the injectors?? maybe I did not do it right?? They seem to be the most expensive 'trial ' part to change so if I can I will clean them again.

thanks for all the responses...I am sure I will have her running soon

...I will keep everyone posted as progression occurs

Plecostomus 05-22-2008 05:14 PM


930cabrioboy 05-23-2008 05:02 PM

not sure what that last post means?

tried holding open the plate and nothing more happened than before

I had some play time tonight and I am now sure that it is pressure related (pump or injector). with the hard line off at the injector there is gushing fuel 1/8 of a small bottle of water with a 5 second key cycle. ..and as soon as I put the injector back on (not in engine, still in bottle) it would not squirt at all. I removed the injector and 40 psi of air will not release the injector pin but 70-80psi will. So I say it is pressure but should the injectors open at a lesser psi? Has anyone tried to push air through thier injector, or does anyone have an old injector to test to help me on this one?

thanks again everyone

Plecostomus 05-23-2008 05:02 PM

thread is worthless without pics :)

930cabrioboy 05-24-2008 04:02 PM

sorry not up on all the lingo.

Now I am sure that it is pressure....I need 87 psi....I need to correctly measure the fuel pressure...anyone tell me wher to hook a meter up to read it correctly?



Wolf300tt 05-27-2008 06:47 PM

This might help

This is the reference I use for CIS questions. Not specific to 930, but generally useful anyway. If you can follow the instruction and not the pictures specifically, you can check your fuel pressures on the 930 engine. From what I see though, you will need 70 or 80 PSI to open the injectors.

Keep plugging, you'll get it.


A930Rocket 05-28-2008 12:04 PM

Stick the red plastic pipe from a can of brake cleaner in the injector and sspray. It should open up and tell you what pattern you have. Been doing it this way for years. Also, soak them in a bottle of Chevron Techron injector cleaner for several days. Check the spray pattern after soaking with the brake cleaner method.

930cabrioboy 05-28-2008 05:12 PM

thank's, the injectors seem to open well with the cleaner method, I have a guage ordered, I should get it tomorrow or friday, I will get back with the results.

does anyone think it could be the check valve in the ront pump or a partially clogged filter?...just a thought that has been bothering me.

the plug on the rear of the air blunger/ beggining of the hard that the cold dstart switch? is so can that slow the pressure? or the warm up valve? can they be bypassed?

thank's ...I will not quit till I can drive her around the block :cool:

NathanUK 05-29-2008 08:51 AM


Originally Posted by 930cabrioboy (Post 3970054)
the plug on the rear of the air blunger/ beggining of the hard that the cold dstart switch?

Not sure which part you are referring to. Please try again. Maybe post a picture.

930cabrioboy 05-29-2008 04:09 PM goes ..remember I am not a, it is right on the backside of the air filter.

930cabrioboy 05-29-2008 04:13 PM

for those that asked for some barnfind pic' you are
sorry for the bad pics...because it doesn't run yet I cant take her out to get some nice shots

930cabrioboy 05-29-2008 04:15 PM

oh forgot to ask can i get an accurate reading of fuel psi at this point?

Alan L 05-29-2008 08:52 PM

There is a switch/plug at the rear of the air plate - that is the safety cut out - no air flowing - no fuel (pumps). When you depress the plate you should hear it click.
The injectors should open at about 50 psi. Your system pressure should be about 90 psi (surplus is returned to tank).
The big banjo facing you on the fuel head is fuel in. You could disconnect and measure flow - about 1100 cc/30 sec.
Depends what union fitting you get with pressure tester , but if poss, you could plug into an injector banjo outlet. This is not the usual way - I just can't remember where I hooked into my fuel head to measure pressure. You can also unhook all injectors - or at least the easier 3 on RHS, and couple up again to lines and see if any work. Careful - if some are the LHS cylinders could be flooding too.
If the piston is stuck , it is relatively easy to get at - disconnect all fuel lines at injector head. Three screws in top of head -undo, and prise head clear of body. Flip it over - the tip you see is bottom of piston. Prise up lock tab (easy) and unscrew(easy). Piston should fall out basically. If grungy , need to clean. You will also be able to see inside of metering chamber. Careful in there - fine surfaces and very fine (invisble ) metering slots. If grungy, clean. Could try blowing bit of air backwards thru metering slots (injector outlets). Careful - not too much pressure - don't rupture slots - about 2 thou wide.
You have a cold start valve which will probably be gummed/rusted shut - about mid manifold, under the fuel head rear. Can't really get at it without removing manifold. But you need fuel at injectors first.

Alan L 05-29-2008 08:55 PM

Sorry - just seen your pics - the big banjo is easy to see. You were pointing at the safety cut out switch. The fuel line you are pointing at is the return. Should work.
On the other side of the head from there is a nut/screw. This is the pressure adjust system - spring/shims.

Alan L 05-29-2008 08:57 PM

Just out of curiosity - is there any gap between your rubber stopper and the top of air plate?

930cabrioboy 05-30-2008 04:38 PM

thanks for the input Alan, there is no gap at the ait plate. That screw you speak of at the rhs ..could it be gummed up and cause some of mt grief? the one I pointed at was as clean as new when I removed it.
The description of prising open was the plate where all the hard lines come from above the banjo that I pointed at? If so I took it part earlier and cleaned it out...seemed clean and since then I have flow up to the injectors...but not enough to spray through injectors.

I keep pluggn'

Ken911 05-30-2008 07:26 PM

wait till you get your cis gauges. then check all the pressures. mine had not been run in 6 years. I had to replace both fuel pumps. filter accumulator. send out the wur for rebuild it wasnt controlloing pressure correctly . plus the fuel head was gummed up also. I did manage to get the injectors all cleaned up so they work good though. now I have an adjustable wur and the imagine auto fuel head which flows a huge amount of fuel.

Alan L 05-30-2008 08:58 PM

From memory I plugged my pressure gear between the WUR and the head - that way you can do cold/hot pressures. The pressure should be low(er) cold and increase. This pressure works against the system pressure- so allows the piston to move more freely (more fuel) when cold. The WUR is the box below Rt of the fuel head - next to the AAV.
Looks like you need to get the system pressure numbers first - but you could unscrew the RHS injectors, and hook them up again and see if any are spraying.
I think the plug you removed is redundant on the 930 - this head is used for other cars too. But it should be recording system pressure with any luck if you can plug into it. If the pressure control valve is gummed, most likely I think you would have over pressure (no bypass). It cracks open at max system pressure - regulates your pressure - which is delivered from the pumps.
Are you sure BOTH pumps are working - and not just the rear one? Depress airplate -jam it part open and get under front of car - between two front wheels and listen for front pump running.

930cabrioboy 05-31-2008 03:31 AM

I am most positive both pumps work but I will do that test in the front, I hear whinning near the gas tank area and near the left rear wheel...I will do the checking and get back soon.

the pressure regulator is located where?

Can the wur be gummed up and give me lower numbers in psi? Can that be taken apart and cleaned?

the more it goes on the more I feel the need to do like everone who has had a car sit for a while...pumps accumulator/filter and clean up the head etc.....I just was hoping to avoid the big costs up front as I am still not sure the full condition of the motor yet..although compression is good, if a rebuild is needed then it will become a winter project unfortunately.

NathanUK 06-01-2008 01:57 AM

Just to let you know that the CDI box in the engine compartment does whine & it can easily be mistaken for the rear fuel pump working.

930cabrioboy 06-01-2008 07:25 AM

can I jump the pumps at the fuse box to test them?

if not I will physically get under and test them, just to confirm the front one is under the plate between the front wheels, and am I correct that the rear is near the left rear wheel?

I am going to get my guage today hopefully I will have some time to test before the day is over.


A930Rocket 06-01-2008 10:18 AM

You can jump at the red relays using numbers 30 and 87 I think it is. You have the location of them correct.

9dreizig 06-01-2008 11:33 AM

Hey Cab, what color is that ?

930cabrioboy 06-01-2008 01:56 PM

thanks will try the pressure guage but lacking a little time, will try once my daughter is asleep

the color is dark blue....

930cabrioboy 06-01-2008 05:47 PM

I had a few minutes to tinker, I ended up taking the fuel head back off, because it was my first problem, I still have a funny feeling that it is blocked a little still, and the plunger still didn't flow like I would like to...will clean it all up completely, because all I did before was blow some air through it to unblock it.

I do have one stripped #25 hex nut of the top three, so I will be cursing in the garage soon enough trying to remove it.

The guage I got did not fit any of the inlet/outlets so I will need to get adapters.

all the injectors are super and breakopen at 70-80psi as they should (tested again) and threw som carb cleaner in it again

both pumps are working fine for those who asked.

the wur is totally clear and although I know not if the electrical side works the flow is fine.
....I must only be off a few psi to get her running

can anyone tell me if there is a fuel pressure regulator that I can tweek or clean? If so where is it and what does it look like.


Alan L 06-02-2008 11:52 AM

Your fuel pressure regulator is on the RHS of the fuel head - the screw /nut thing I mentioned earlier.
Your WUR will not be the problem even if it is gummed. It just controls the piston head response during the warm up cycle by varying fuel pressure on top of the head. Either way, you should have enough pressure to work.
Something wrong with your injector opening pressures. If that truely is the pressures (70-80 psi), they are way too high. And may explain your lack of fuel at injectors. You need to be able to measure your system pressure - it may not be much more than your injector pressure.
Opening pressure should be around 50 psi. Some injectors have small filters incorporated - don't know if the 930 has or not - but maybe they are blocked if you have such high pressures.
Jack the car up, and when pumps are running, put your hand on each of them and feel the action. May have to drop the front bash plate for front pump - at least partially (easy - apart from frozen bolts/nuts).
The elecricla part of the WUR is fairly simple - but an ohm meter across the two terminals on the WUR socket and make sure there is continuity circuit with some resistance (heater wire).
If so, as long as you get 12 v on the plug when idling it is going (apart from any possible gumming). If you hook your CIS pressure system between the WUR and fuel head (on the ferrule fittings) you will measure the WUR working - pressure will rise as engine warms up - 5- 10 minutes. Write down cold and warm pressures for future reference. While you are in there.

930cabrioboy 06-02-2008 04:26 PM

thanks Alan, I did want to mention that there is a gap at the air plate between the screw and the rubber stopper, as you asked this before...I had not paid attention to the question.

The injectors crack open at 70-80...all of them, I was told this is normal but you state that 50 is a better number. If they cracked at 50 I would not be having this topic as I am sure my pressure is in the 50-60 range because at the injector with the injector removed I fill 1/8 of a cut waterbottle with the 2-3 second cycle of the key....and it keeps leaking after the key is turned off...pressure dies out.

Does anyone have a set of injectors that are good I could buy-borrow? or can I interchange them just to test with old vw units maybe?
buying new ones is not a problem if it fixes my issues...expensive trouble shooting gives me a sour taste when it doesn't work.

Alan L 06-02-2008 05:05 PM

Check your total fuel flow rate - it is easy - pull the big banjo off in the middle front of the fuel head - there are two big lines - the one on the LHS is the return line.
Put the banjo end into a measuring container and push your flap wide open for a timed 15 - 30 secs. After 30 secs you should have about 1100 cc fuel.
Your system pressure is supposed to be 90 psi (book value) +/- a little bit. If it is slightly down, with injectors opening at 80 psi, you won't get much fuel.
Book value for injectors is 30 - 45 psi. Something wrong with 80 psi.
May not help - but you can try flushing them backwards - in case they have screens and they are clogged/gummed.
You need to make up a non - abrasive little tool to hold the pintel (nozzle pin) open - I cut out a small V in shim plate and rubbed the edges down smooth. Then insert hose over end of injector (incl pintel tool) and push fuel/cleaner backwards. See if any crap comes out other end.
What gap approx is on your air plate/rubber. I'm trying to mount one, but I have about 10 mm gap and can't see how it can be any use at that point.

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