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mdregister
06-30-2004, 13:26
Ok, I will keep this as short as possible.

I am a complete newbie to diesels, so bear with me..

I have a new (to me) 1985 3/4 ton Chevy Suburban K20 6.2L J code 4X4 with a three speed automatic (th400) and 119000 miles. Dual exhaust.

When I first picked the truck up a few months ago, everything seemed fine. Well, fine as far as I know, I do not have anything to compare it to as I had never driven one of these before.

Sometime later, after a few hundred miles and a few trips onto the beach, the truck developed a loss of power and a miss, along with a small amount of black smoke at idle while in gear. I took the truck to a diesel repair shop and they advanced the timing by rotating the injection pump. The miss went away, but still had a small amount of black smoke "puffs" while at idle and a small amount of steady black smoke underacceleration (proportional to engine/throttle speed).

All seemed fine for a few days but later noticed an intermittent loss of power from a dead stop, which is where I am now.

I replaced the lift pump on someones suggestion and noticed an improvement right away (even my wife who never notices such things commented on the increased power). While things are better, I still feel like I have a power issue.


From a dead stop, my poor old dead grandmother could roll her way faster to 15 mph or so. After that the performance improves but still varies from time to time.

The previous owner had the injector pump rebuilt after it crapped out on him in florida at about 80,000 miles. I believe Accurate Diesel did the work.

I have also put on a new fuel filter and air filter.

While no longer having a dead miss, I think there is still a slightly rough idle, but there again, I have nothing to compare it too. I also note a slight "miss" with slight throttle and the transmission in park for just a few hundred rpms maybe. Sorry no tach, can not tell the exact engine speed.

I have also noticed the truck runs much better when the air is cooler. I know this is the case with most engines, but I cant believe all of my power loss is due to the heat.

No air in the lines as far as I know. I have checked the return hose on the top of the IP and there are no bubbles/foam.

No hard starts at all. In fact, as soon as the plugs warm up, it usually fires right up with a turn of the key.


Suggestions?

Mike

Ratau
06-30-2004, 22:06
You could start by checking the injector nozzles and pop pressures. Here in South Africa the testing is free.

Danie