Running like Sh*t...PLEASE HELP!

[roverboy]

Hi guys, I'm in need of some help.

I have a 1994 D-90 ST with 123,700 miles on it. It's my daily driver and has been running great until about 2 weeks ago.

Here's my problem. Sometimes the truck will surge, sometimes it will surge and then cut off. Sometimes it just cuts off unexpectedly. This happens whether I am at speed, or in traffic. Whether it's cold or hot outside, and whether the engine is cold or warm. When it begins acting up, it smells STRONGLY of exhaust...or like a rich gasoline mixture. When the truck actually does cut off, it sometimes takes as long as 5 minutes or so to crank back up. When I am trying to start it, it sounds awful...like it' not turning over, and white smoke sometimes pours from the exhaust. Sometimes it cranks back up immediately. When I do get it started, it runs like a top...no smoke, no smell, nothing. Also, I have noticed that since this has begun happening, my gas mileage has dropped from about 13 MPG to around 9 MPG.

I need to mention that I have had BOTH catalytic coverters replaced about a year ago, and my ECU is from a friend's wrecked 1995 D-90 SW (and has been installed for the last 2+ years wth no problems.) Since the new ECU has been put in, I haven't had the truck in enough deep water to wet the unit, and I don't think that enough rain gets to it to wet the inside of the unit, but I'm not completely certain.

Can anyone out there offer up any possible causes or solutions? Has this happened to anyone else? I had this same thing happen a little over a year ago and I took it to the dealer to have them diagnose it and they couldn't find anything wrong with it. (my dealer TOTALLY sucks, I'm not even kidding, but that's another story.) Anyway, I never fixed it then and the problem seemed to just go away. Now it's back and it's worse than before. Anyone want to venture a guess as to what this is all about? I need help.

Thanks...

tom

[Mike Hippert]

NO codes from the ECU?

[Neo]

Tom, Sounds like a sensor to me too (which is what I believe Mike is eluding to in his post). I would check the digital display for codes. It sounds very much like the ECU is sending too much fuel, although usually, black smoke belches when you are way over rich.
BTW: I met your wife the other evening (Friday) at the Cinema. She said you were in line. Sorry I missed you. Give me a shout if you want to get together and look at it. I love working on these things!

Jeff

[roverboy]

That would be great Jeff! Drop me a line and let's see if we can get together. You busy this weekend?

As far as the fault code goes, when I took it to the dealership for this problem last time, it hadn't registered a fault code so they couldn't diagnose the problem. They supposedly took it on a test drive to see if they could get it to act up, but were never able to get it to duplicate what I had described. Instead of researching it or keeping the truck longer, they simply gave it back and said that there was nothing wrong with it. Like I said...I'm not a big fan of my local dealer.

Anyway, I'll try and get a fault code reading on it myself tomorrow. In the mean time, does anyone else have any thoughts? I'm all ears.

[nmarkiw]

Several things could cause this.

First, the hard starting/poor idle issue is most likely a leaking injector. Since the 14CUX is bank fired, the computer madly tries to compensate for the extra fuel in one cylinder. This also accounts for the poor mileage. Pull the plugs. ID which one is black, and smells of fuel. This problem produces black smoke when it does start and a strong fuel smell.

The white smoke is curious. That indicates burning coolant. Again, inspect the plugs. They will tell all. This could be a blown head gasket or a leaking sleeve.

Verify the color of the smoke, coolant level.

Nick