Black Smoke; fuel sending unit o-rings

[chris_maxwell]

I have had an issue with black smoke for some time. I have a feeling it has to do with the marine injectors I used 10,000 mikes ago. My Banks chip is only able to max out 10-11 boost so I think I have a lot of unburnt fuel under load. Add to that I used the Clearwater heads and I only get 10-12 miles to a gallon. Otherwise the truck seems to run fine, especially under light load.

My fuel gauge was jumping around so this weekend I changed the fuel sending unit which was a pain in the butt. Problem is I didn’t notice the two small o-ring that go on the end of the metal lines. It doesn’t seem to be leaking fuel, but I just filled the tank so I can’t do anything at this point anyway. Do you think this will add air into my system and create problems? Should I run this tank down and install the o-rings? Do you think I can do it without dropping the tank and or trying to remove the bed of the truck?
What gauges does everyone recommend? I just installed a new vacuum pump which is working, the solenoid seems good, but I still continue to get the black smoke especially when I use the AC or when it is hot outside, and it is hot here in Atlanta now.
I thought about trying a Kennedy or Heath chip but I don’t want to spend the money if it isn’t going to improve the drivability/smoking issue. I have a 4” exhaust and the cat is punched out (when I moved back to WA they will look for the thing). The PMD is remote mounted and I have an AFE air filter installed which is clean.
It is a 95 GMC with 145,000 miles on it; there should be lots of life left on this thing.

[JohnC]

How much boost do you actually have?

The injectors do not determine fuel rate; the injection pump does that.

[chris_maxwell]

I'm not sure what I have because I haven’t put gauges in. When I had it at the shop they said it could produce 10. Most of the time it was between 0-3 I believe. I throw no codes what so ever.

[Robyn]

If your getting BLACK SMOKE there goes your MPG

The clearwater heads are using a Precup that is about the same as the GM Diamond cup.

These are Power cups. I have used these same heads and have seen 20 MPG numbers on a 6.5 .

The marine injectors are in my opinions a waste of $$$$. The IP can only shove so much fuel. The DS4 will under prefect conditions and with the right chip calling the shots, deliver no more than 90cc of fuel per 1000 strokes.

I prefer the stock injectors in top notch condition set to the top of the POP pressure spec.

Make sure the Timing, TDC offset and such are all where they should be.

A max boost of about 12 PSI on a hard top gear run under a good load is perfect.

Much more and the IAT is going to be too high.

As far as the fuel line O rings go. Better get that fixed.

Pulling the bed is not the most inviting job but, the lines are originally installed while the frame is bare. The body goes on after the powertrain is installed.

10-12 MPG is on a very low end of the scale. These rigs should be able to get close to 20 MPG hwy and 15+ city.


TDCO is a very important factor in the power and MPG arena.

Good luck and keep us posted.


Missy

[chris_maxwell]

What is TDCO & IAT?

I had the timing and TDC offset to the recomendations of the club....can't remember the specifics of all that but they set it as close to 1.94 as they could get it, i believe it is slightly under. I have wondered it it might run better @ 1.5 (i believe it is -) it was a .75 prior. They did the learn and everything. i beleive they are members but are more on the hummer side than the trucks.

if i had it to do all over again i would use the stock injectors (i still have them but don't know a good shop in HotLanta). how much is reasonalbe to rebuild them?

not what i wanted to here on the o-rings; but figured it was the correct thing to do.:p

[DaveBr]

Check your turbo for bearing play. If you have movement you have black smoke.

[Robyn]

TDCO = TDC Offset sounds like your right where you should be.
IAT = Intake air temperature

As the boost pressure goes up, the temperature of the air increases.
Above 12 PSI on an engine without a charge cooler the increase in boost pressure results in a direct increase in Exhaust gas temperature "EGT"

I dont like to see EGT pre turbo above 1000F under full load.

With your TDCO set properly I am suspect that the mileage issues and smoke are related to the combination of the injectors and the Chip thats in the computer.

Try swapping the stock chip back in and doing a mileage run.

I have no experience with the Banks chip so can't comment on how good their program is.

Banks has always offered good products of the years but again, can't comment.

Fuel, when it's injected, timing and boost all play an important part in power and economy in these engines.

To fully diagnose the issue, you really need to put a scan tool on the truck and drive it. Monitor fuel delivery and all the sensor data.

First off with the truck let sit overnight or longer with the hood open.
Check the readings on the coolant temp sensor, this should read fairly close to outside air temp. (Scanner needed to do these tests)

Check the intake air temp sensor, same thing, should read near ambient temp ((make sure the truck is not parked in sun where readings can be scewed.

Check the Baro sensor reading, it should read near what your local barometer reads.

Fuel temp should be close in there too.

Fire the rig up and watch the sensor readings. The coolant temp sensor readings should fall right in line with whatever the gauge reading are.

Running down the road, observe the boost reading on the scanner
(MAP sensor) = manifold absolute pressure.

This should read very close to what your gauge reads.

Major anomalies can indicate issues.

All these sensors allow the computer to control the fuel delivery, and if they are not working properly or if the readings are way out in the sticks then fuel economy and power can go right out the window.

Black smoke indicates either not enough air or too much fuel.

Now, I see that the rig has 145000 on the clock.
Stock exhaust or has it been upgraded ??

The 95 will have a Cat/soot trap on it. These things plug up over time and this drastically fouls up the airflow through the engine.

Check the sensor readings and such first and then if all things fall in close to what they should be, then suspect other things like exhaust.

Be sure that the air filter and the snorkel in the fender are clean and free of crap.

More than once a critter has set up houskeeping in the fenders of one of these rigs and this will really plug off the airflow.

Check the easy stuff first and then move on.

Dont spend a bunch of $$$$ on goodies until you can nail down what is NOT wrong with the truck.


Missy

[JohnC]

My experience is that the '95 will not set a code for low boost. You need to figure out what you got...

[chris_maxwell]

What is the routing for the hoses for the wastegate solenoid? The rubber adapter is off and the replacement rubber hoses plug directly into the solenoid. Does the one from the pump go to the side to front of the truck or towards the cab?

I bypassed the solenoid and I get like a brownish gray smoke rather than the black, does this point to anything?

[chris_maxwell]

The other thing, and I don’t want to just jump to the turbo master is I can move the actuator but there is some resistance. When the engine stars it does close however. I wonder if maybe this is causing the black smoke. Where is a good place to but the old pillars gauge setup? Most stuff out there is for the Duramax now.

[chris_maxwell]

I finally was able to drop my fuel tank for the o-rings; boy did I feel stupid as they were already installed :o. They supplied an extra in the box, which was good because once I disconnected the fuel lines the o-rings should have been replace, so I did and now I am at ease about that anyway….:cool:

My truck never through any codes but I found a wastegate solenoid at O'Reilys for $25 so I thought what the heck. I had tried previously swamping it out with another guy who had purchased a new one but it didn’t make any difference. After replacing it 90% of the smoke disappeared:D; the majority of the smoke was running in the afternoon when the heat index was pushing 110. Even first thing in the morning the thing felt better. Not sure if all my problems are gone but I am going to fill the tank and see what type of mileage I get. Hope it is a lot better than the 10-12 I was getting, be nice to get back near the 14-15 I used to get at 50K.