I have a 740 turbo wagon that has been dead for a few weeks now. I've been reading the articles in this forum in hopes of fixing it but so far it still won't start.

First the car would start fine but when I turned it off, I couldn't get it to restart for a while. Then one day a few weeks ago, I driving on my road and it just died and wouldn't restart. Since then, I've got it to start but it would quickly shut off and now the car won't fire at all.

I've done a complete tuneup (plugs, wires, distributor, rotor, etc), changed the fuel pump relay and radio suppression relay, and changed the fuel pump out side of the tank. I verified that all fuses are good and all vacuum lines are also good and in-tact.

So today I tested the ignition coil and verfied that 12v of power exists when I crank the engine. I also removed a spark plug and grounded it to the engine block with a wire and verified that a healthy spark IS firing.

HOWEVER, when I cranked the engine with spark plug from cylinder # 2 removed, I noticed an excessive amount of gas spraying out of the whole. I mean it was A LOT of gas. I removed the fuel return hose from the fuel pressure regulator to see if the FPR was frozen shut but nope, a steady line of fuel shot of the FPR.

I then proceeded to crank the engine with the fuel pump fuse (#1 I believe) removed. When I did that the engine turned over and then began to catch until all the fuel was burned. I replaced the fuse and tried again but then noticed fuel spraying out of the dip stick!!. There is so much fuel in my car right now that it made it's way to the oil pan.

So... there IS spark and there IS fuel but it seems like there is just too much fuel spraying out the injectors causing the engine to flood and making the spark plug unable to ignite it.

So what can cause and excessive amount of fuel to enter like that??? Do you all think the problem is too much fuel being sprayed or is it something else?

Thanks and sorry for the long post.

 

First replace the FPR if fuel was coming out of the hose it is bad.
Then change the oil.
Then make sure the injectors aren't leaking.

 

The fuel wasn't coming out of the vacuum hose on the FPR. It was coming out of the return side of the FPR like it normally should. This was just done to see if it was clogged which would cause excessive pressure at the injectors.

I did drain the oil today approx 3.5 gallons of gas and oil poured out. Ouch! It's a good thing I never got it running because I would have cooked the bearings and/or seized the motor.

We'll see if she'll start tomorrow after I flush the engine with deisel oil about 5 times. Remember, the original problem was that the car would start perfectly the first time but would not re-start if it was turned off. I hope to have cured that problem by the fuel pump that I just replaced.

 

more likely fuel pressure regulator. Have you checked the fuel pressure? If it is too high you get excess fuel. Fuel pump could not cause this problem that I am aware.

 

This is what I thought. However, I removed the fuel return hose (not the vacuum hose) from the FPR and watched a steady stream of fuel flowing out of the regulator. I guess it could still be blocking the fuel a little but I can't imagine that it would be enough to flood the engine withing a few seconds. Never the less, I don't have a fuel pressure guage but will source one from a friend and test it. What is normal fuel pressure for an 87 740 turbo? Thanks.

 

I believe it should be around 30 PSI.
Can't find it in my Cheater book.

 

I didn't check fuel pressure yet but I did remove the fuel rail and injectors from the intake manifold last night and had a friend start the engine so I can see the fuel spraying from the injectors. The injectors were pulsing and spraying normally. And they weren't leaking in between sprays or after the car was shut off.

So it's probably a timing issue because I AM getting spark and I AM getting fuel.

I know the belt didn't break so the ECU may be screwed up. The weird thing is that the problem is VERY consistant. The car starts perfectly and idles smoothly when it's cold but if it turn if off after it warms up, it will not restart. It doesn't do this intermittently, it will do this EVERY TIME.

Thanks.

 

Maybe Coolant temp sensor or Mass Flow sensor.

 

If it was the Coolant temp sensor or Mass Flow sensor then wouldn't I see an engine light? Currently I see no CEL.

 

Not always.
It might be out of range but not enough to throw the CEL.

 

Tonight I installed a NEW coolant temp sensor and replaced every bit of vacuum hose with new hose. The car started and ran but ran horribly and was very sluggish. However, when I shut if off after running it for about 2-3 minutes, I attempted a restart and it started right up. So THAT problem seems fixed.

Along with sounding horrible and feeling sluggish, the car was smoking like crazy around the spark plugs specifically near cylinders 2 and 3. I seems as if there is an exhaust leak but I can't feel anything when I stick my hand down there. I smells almost like it's just oil burning off because and any oil spilt when filling up the valve cover will drain down to the middle spark plugs holes. Any yes, I verified that the plugs themself weren't loose. Also, the engine wasn't shaking like one or more injectors weren't firing or timing was messed up. It felt very smooth but just very weak and that smoke.

So any more suggestions? Thanks

 

Maybe the turbo.
Make sure the turbo didn't seize.
Also maybe Mass Flow senosr.

 

The turbo is fine. I checked it yesterday.

The car idles beautifully now, so I'm not yet convinced its the Mass flow sensor. I drove the car yesterday and it was very sluggish after 2000 rpms and even stalled out. However I was able to restart it so that problem is still fixed. I feels like the timing is off either caused by a bad ECU or a timing belt that has jumped.

Tomorrow I'm going to do the timing belt. But willl I need any special tools? I noticed that autozone rents a tool for removing the harmonic balancer but I've always been able to remove that with a rubber mallet on my BMW or Audi when I've done the t-belt on them.


Thanks.

 

You will need a tool to hold the balancer to loosen the Bolt.
Even if you have impact guns most won't fit to loosen the bolt.

Some have used a Long breaker bar and set it on the Ground and bumped the key to loosen the bolt.
But the hard time comes when trying to tighten the bolt.

 

I changed the timing belt yesterday. Thanks for the breaker bar method. It worked great.

HOWEVER: Timing was perfect. So that's not the cause of the poor running performance. The car is still running extremely rich. I've only run it for 10 minutes since I replaced the coolant temp sensor and already the spark plugs are very black and sooty. FYI, the plugs were replaced after the car would never restart so they only have exactly 10 minutes on them.

I guess I'm going to have to replace the ECU. I haven't changed the MAF or O2 sensor but I can't image they are the cause of such an extreme rich condition. I also don't have any engine codes which you typically get with the O2 sensor and MAF.

Is changing the ECU the next recommended course of action?

Incidently, Can I get my ECU tested somewhere before spending $450 on a new one???

 

Can't get it tested as far as I know.
Have you tried checking the o2 sensor sweep?