bxtech

Hello all,

My 1986 928 all of a sudden started running excessively rich. Fouling plugs, black smoke, flooding. Pulling the spark plugs........all 8 are wet. Was thinking that the problem might be the coolant temp sensor. I changed the sensor and there was no difference.

I remember reading about someone with this exact problem years ago, but I can't seem to find the posting. I'm not sure if it was even on this forum.

Has anyone had a similar problem like this? Anybody that can offer some advice or experience would be greatly appreciated!

Thanks in advance!

Calgary Ole

No exp. with 86 but could it be the fuel pressure regulator has failed?

Mrmerlin

pull the vacuum lines off of each of the fuel dampers and the fuel pressure regulator smell the line for fuel .
If you smell fuel then the part needs to be replaced
Is the 02 sensor new?? and is it connected

bxtech

Thanks for the input! I'm going to check out the pressure regulator. I believe that there are two......correct? One for each bank? Do you think both could go bad at the same time? All 8 cylinders are fouling. Thanks.

Shane

Could also be a failed MAF. Do you have someone nearby that can test yours or allow you to try theirs?

John Speake

If no fuel in the vac lines, then unplug the O2 sensor and test again.

If still rich then MAF thermal runaway is very likely. Pull the engin airfilter, switch on the igntion withoiut starting the engine and look into the MAF. If it has bad thermal runaway you ill see the hot wire glowing red hot.

THis is repairable, see my website for an agent local to you who will test and replace as required.