89 951 run/idle issues VERY RICH
 

Hello, and thanks for this forum. From a newbie.

Just bought an 89 951, 133k, timing belts changed at 50k intervals, maintenance records, been basically unused for the last 3-4 years. Best I can tell in excellent shape.

My problems-

Runs very rich at idle, black smoke, idle erratic, will flood out after a few minutes at idle. Starts easily, and restarts easily at all temps and even after dying.

AtRPM around 4k, blows clouds of black smoke, bogs down, and almost dies, let off the gas and go back to partial throttle and it picks up again and rolls, still with some black smoke. Happens most often at WOT.

Fuel pump is making a whining noise like running through gears at idle, a progressively higher pitched whine, then resets itself to lower pitch and begins again. As far as I can tell, it is noisy throughout the operation range.

There are no lights on the panel indicating trouble with the Motronic, or O2, but I'm new to the Porsche setup so....it may not operate as I think it sould. (BMW's Audi's and Volvo's in my own experience)

After the car has been run awhile the transmission is reluctant to go into reverse, it needs to be forced, not good for synchronizers, what could this be?

Where is the best source for a good (not Haynes) repair manual, or set?

I've not had time to search the posts yet, just wanted to take a sec and see if this is something common that is encountered. I'm eager to get this car running like it should so I can use it as a part time stop light racer and weekend with the wife cruiser, I do my own work when possible so please make your suggestions clear and as simple as possible. (pics are a big help)

Thanks!

RE: 89 951 run/idle issues VERY RICH
 

Take a look at www.clarks-garage.com for some very good info.If the car has had the timming belts for four years and been sitting around without much use, you should chaange them asap.Your problem could range from fuel pum to pressure regulator or even turbo boost. Take allook at clarks and get some new belts.

RE: 89 951 run/idle issues VERY RICH
 

sorry about the above typing... thats what happens when the dog helps you type

RE: 89 951 run/idle issues VERY RICH
 

I would check your fuel pressure to start with, and see what it is. I would start with a new O2 sensor for your black smoke, as well as a DME temperature sensor. There is no CEL light on your car, or other warning indicators from the motronic system. Does the car have stock chips in it? Is there a lot of oil in your intercooler pipes? What are your compression numbers? You probably have a lot of carbon built up in the engine that needs to be burned off after sitting so long. Check all your vacuum connections as well, typically after 20 years, most of the rubber lines under the intake are hard as a rock and very brittle, thus not forming proper seals.

RE: 89 951 run/idle issues VERY RICH
 

Thanks kinderrich and PorscheDoc, much appreciated.

Any advice on changing the timing belts and noisy fuel pump (should it be whining like that?) on this model?

RE: 89 951 run/idle issues VERY RICH
 

Not sure about the fuel pump, when you check your fuel pressure you should have a good idea about that. I would change the water pump when you do the belts, but I am paranoid about that. While your there, you might as well know the front of the engine is good. Check the rollers and maintenace recoords to see what has been done before and when.

RE: 89 951 run/idle issues VERY RICH
 

Fuel pump will whine a bit, but you really shouldnt be able to hear it if the car is up and running. If it is whining loudly, then you are probably looking at a new pump soon.