1986 930 Will not start

[Ringnalda]

Hello all,

I'm getting much more familiar with the circuitry for my 930, but still
haven't found the problem... These are the facts, can anybody tell me what
the cause for not starting is?

The car ran fine, then the starter gave up. I replaced the starter, and connected everything back up again. Now the engine cranks but will not start. Grr.

1) I have a nice good spark at the plugs.
2) When I by-pass the fuel pump relays, I get fuel pressure but the car will
not start.
3) When I take off the intercooler and the air filter box, and hold down the
mass airflow sensor plate, the fuel pumps run during cranking and YES I get
cylinders to fire, so the CIS unit is probably not injecting during normal
starting when everything is connected. Does a 930 suck enough vacuum to
pull the mass airflow sensor plate down during starting? Have I got a big
inlet manifold leak? Can's see an obvious one...

So I am suspecting someting has to bypass the mass airflow signal during
cranking to switch on the fuel pumps and allow the CIS to inject fuel into
the cylinders. I have checked all 4 connectors on the starter; when I crank
I get 12 V on every one, one is triggered by the ignition key (obviously
works since the engine cranks), the other is triggered +ve by a solenoid on
the starter (going to the cold start valve) and also works. One is
permanent +ve and connected to the battery and also the alternator... These
connections are all good...

Any insight will be much appreciated. I fell I'm getting closer but still
no solution. I'm seeing an airflow bypass sensor and a delay relay as well
as a warm up relay in the schematic, but I don't know where these are.

Cheers, Jan

[carmad]

In the 1st picture, the red capped hose is attached to the warm up regulator (WUR). The thicker hose bottom right is the Aux Air valve (AAV).
In second picture the blue connector is the cold start valve on the rear of the manifold.
Hope this is of some help in identifying components, this is an 86 CIS system.

Julian

[john walker's workshop]

check the hose on the left side of the turbo for a crack, the air that moves the sensor plate has to have a sealed passage between the throttle, thru the turbo to the plate. anywhere air can get in will limit the sensor plate movement.

[Ringnalda]

Hi John,

Thanks for the tip. Does that mean that during starting, the mass airflow sensor plate movement is not by-passed?

Jan

[john walker's workshop]

you get voltage to the cold start valve from a terminal on the starter solenoid, cold only, but the sensor plate always moves.

[Ringnalda]

All,

I checked hoses where I could see them, and put everything together without the air filter. When I put pressure on the sensor plate, and turn on the ignition, there is much more force on the plate to push it back. I assume this is normal. Also when I try to start with the pressure plate depressed slightly, I get more life out of the engine, but it still will not start. But at least it tries. It pops and burbs and I get a huge amount of smoke out of the inlet area after it tries to fire. But still it will not run...

[steven polaski]

try sprating a little starter fluid into the air flow sensor ( while depressed ) then crank it. If it pops then your fuel flow is the problem this happened to me. The fuel is going to the bosch distributor but the valve is sticking. Good luck

[Ringnalda]

I've tried that, but I can't open the butterfly valve and the sensor plate and crank the engine... Will try again with more hands.

[steven polaski]

spray the fluid into the airflow not the butterfly then while some one cranks the motor hold the air flow meter open a little. You can also remove one of the fuel injectors and put it in a glass jar and turn the key on watch if fuel is going into the cylinders correctlyyou can move the airflow meter up and down to increase or decrease the gas flow.. When the fuel dist sticks it will only run when the airflow is enough to burn the gas. To much air or to little no fire. If you take the fuel dist off becareful do not take it apart ! Grab the piston with something soft and move it in and out. This is a delicate and exspensive part so be careful !!!

[steven polaski]

Also the airflow valve plate is like a soft gas shock smooth and easy to push on and instantly returns if it pushes hard thats your problem you take off the fuel dist and slide the piston out gently clean it with a rag this is a critical fit so they will stick especaily if the was sitting and gas is old.

[Ringnalda]

Yess Sirreee,

Finally, my turbo has sprung into life again.

Talking about Murphy... Engine was being spun the wrong way by the new starter. I'm gonna shoot something...

Soooo.... I had fuel, I had spark, I had everything except for the wrong momentum.

What a nightmare. I am in the process of 'discussing' resolution with the vendor who sold me this starter. Watch this space to see if he wants to resolve this amicably or if he really wants this publicity...

What do you think; I lost use of the car for almost two months, spent countless hours checking everything, gave up and had the car towed to a dealer who also spent two days. And I haven't seen their bill yet. What seems reasonable?

[john walker's workshop]

i ran into that on bosch starters supplied for 944s, years ago. guaranteed to leave you saying WTF for a while.

[Ringnalda]

Trust me, I'm still seething...! But thanks for all the pointers. I found a split intercooler 'O' ring, suspect ignition relay, and some other relays that should have been replaced anyway. But WTF...

[MobileWrks]

if you look in the first pix, there is a green plug, on the back of the sensor plate. That ties into the relay, and kills the pumps. Somtimes they go bad,(RARELY) if you unplug it, you will have constant fuel running once the ign is on.
If you took it to a dealer, and the tech dont know crap, your spending time as he spends on it. I know cause when i worked at the shop, we had a car we were not to good at diagnosing wiring, especially with no schematic. ALOT OF MONEY!!!!!!! dont ask....