oliver foster

I have a '97 12V with 230,000 miles I am working on.
I does have pyro and boost gauges, and a complete Banks power pack system installed
It have been acting like it has a fuel delivery problems so...

I have swapped out the LP, OFV, fuel filter, swapped to the earlier '94-'96 filter housing, and installed new fuel lines where needed.

It sputters and white smokes HEAVILY [like a KISS concert] on start up if it has sat for a day.
It also does this after being fully warm, when revving OUT of gear [5 speed] up about 2000 RPM.

I get 20 PSI of fuel pressure at idle and 35 PSI at 2000 RPM.
PSI reading taken AFTER the fuel filter.

It only builds that 10 PSI boost [under no load] when the sputtering/white smoke starts [2000 RPM] when revving it up.
It also goes from 300 Degrees to 600 on the pyro., so it is getting plenty of fuel.
I have NEVER seen a 12V build any boost under NO load.

When on the road there are times it runs great , good power, 30 PSI, 1,200 pyro temp and busts the tires loose in 4th, other times it is low on power, sputters and smokes, at / around 2000 RPM, but is fine under that RPM range.

I am not sure my next move...

It does have a Cummins exhaust brake…

Could the exhaust brake be the problem?
Waste gate issue?

torquefan

At first, your post sounded like your timing had slipped, but after reading the last half where you indicated that the problem is intermittent, I changed my mind. The next place I'd look is toward your fuel shutoff solenoid. Sometimes they can get gummed up inside and not pull up all the way when you start your truck. When this happens, they can partially restrict the fuel delivery into the IP. This causes low power, and honestly it's been a long time and I can't recall if the rest of the symptoms are usually induced too, but it's worth spending a few minutes and having a look at it.

oliver foster

Sorry I forgot to add my old FSS was sticking and I replaced it with a good one and even ran it just on a pull cable with the same results…
I am kinda stumped, especially with the 10 PSI boost at not load revving it in the driveway.

gorms

I'm not sure if the exhaust brake engaging/hanging up would cause any white smoke, but would cause boost free revving. Timing slipped should cause the same problem all the time....could be a problem with the pickup tube in the tank sucking air?

Hopefully its not something hanging up in the pump....does a dead cylinder or two act enough of a load for 10psi?

etn550

Given the recent work this sounds like an air in the fuel problem of some sort. The poor combustion is likely causing some additional late burning in the exhaust system and on the exhaust stroke which is developing boost.

The exhaust brake by itself should not cause white smoke once the engine has been running a few minutes. White smoke is fuel or antifreeze and the smell is distinct as to which it is.

Did all the lines get a good bleed at the injectors?

oliver foster

etn550
All lines where bleed at the injectors.
I have had the truck running for about 3 hours since all the parts where installed, and it still acts the same.
The white smoke smells of diesel.

Gorms,
I have though of using a temp. gun to read the exhaust manifold and see if I could pick up a colder cylinder. I may borrow one and check that next.

I don't think it is sucking air as the tank is half full.
I pressurized the tank and fuel lines to the motor to help bleed the system after installing the lift pump and filter housing, and I saw no fuel leaks under 10-15 PSI pressure

Don T

do you think that after you pressure checked the fuel lines and tank with AIR that you might have a lot of air in the Fuel ?

oliver foster

Pressure testing the tank at the filler cap, should be just sending fuel, and not much, if any air into the lines, as it is picked up off the bottom of a half full tank

Even if I did get air in the fuel, it has run for 3-4 hrs now in 30 minutes a day spurts for a week with the same results.
I would think the air would be worked out of the system…no?
I could crack all the injectors again if you guys think that would help.

Would air in the line explain the 10 +PSI of boost built revving in neutral above 2000 RPM?

patdaly

Oliver, did you ever figure this out?

For the life of me I can't think of any way for the boost to hit 10PSI free revving unless it is a funky boost gauge.

Any way you can install a short piece of clear hose on the return line to be able to visually assure no bubbles on first start?

Air is the only thing that I can think of that would cause what you are describing.

oliver foster

I didn't get a chance to start it and mess with it at all today.

The boost and temp build as the white smoke rolls out the exhaust…WTF?

Next:
I plan to crack each injector [again] 1 at a time, while it is running and watch for air bubbles.

Then maybe borrow a temp sensor to check the exhaust manifold for temp differences…?

I could see if I could get some clear tubing for the return line, as well to check for air bubbles.

I mess with these 12V motors everyday and I am scratching my head on this one.

torquefan

I am thinking the same thing, never seen that in many years of working on these trucks. Basic reasoning tells me that to build pressure there must be restriction, but what can be restricted? Exhaust?

patdaly

Well, if the exhaust is restricted, then how do you get the additional flow to spin the turbine? I could see if it were something like a variable housing, but that's not the case.

I dunno, the more I ponder on this one the more confused I get, it is acting almost like a Democratic politician these days, up is down and white is black......

Perhaps an Exorcism is in order?

etn550

Does it seem like one cylinder (injector tip) or is it smoking and running smooth across the board?

Keep trying different things. Everything different will continue to narrow it down.

The fuel system can suck air into the lines anywhere from the lift pump backwards to the tank pickup and never leak fuel when parked.

Keep checking the easy things first.

Make sure the oil does not rise or get too much fuel in it or if it smells like fuel. Do an oil change often to prevent fuel dilution and related thin oil problems if run much with poor combustion.

After re-reading your posts I think that it is surely getting air in the fuel and I would check all the hoses and fittings you have installed. The fact that it cleans up and pulls hard "sometimes" indicates the problem may be intermittant. White smoke is poorly burned fuel. Address that first and the rest may follow. Clear tubing on the return of the pump is a good idea.

Any air or exhaust side blockage will cause black smoke if the fuel system is good. White smoke is bad fuel spray which can result from air in the fuel, or a bad tip. A bad tip is usually a miss at idle.

Consider that as rpm goes up with no load the injection quantity per stroke is extremely small, less than idle. It would be most sensitive to air at this condition. And the opposite at high load where you say it can run well. Lots of fuel and air may be less in the lines in relation to fuel and the velocity of the fuel in the lines is higher to push the air out or at least make less of an effect.

In fact air tight fuel systems can work the air out when run at higher load and speed. Its the air re-entering and getting trapped in the system each time it goes back to low load.

If your timing is stock see if the timing pins will go in to confirm timing is okay. Or pull #1 delivery valve and check the timing with an indicator. Possible but I don't think likely.

oliver foster

Thanks for all the input guys!

It does run "lopey" on 4/5 cylinders at first if it has sat for a day or two then clears out to a smoothy idle after 30 seconds.

I am going to test the cylinders [temp gun] at cold start up and see if 1 or 2 of them are hotter or colder than the rest.

I like the clear fuel tubing idea…would Napa have something like that which would be diesel compatible?

I am thinking a bad injector which is dribbling the fuel in might be causing the smoke and maybe the un burned fuel in the exhaust is building the boost???
I have a spare set of used injectors off a running 12V I can throw in if the temps are different.

I don't have the truck on the road right now so I can't road test it under load.
I can drive it around the shop.

I have learned since I bought this truck, the last THREE owners have sold the truck, since they couldn't figure out this problem.
The last two owners only put about 200 miles on the truck a piece before selling it again.

I bought it already warmed up, and when it white smoked and stumbled a little up high in the RPM range, I assumed OFV or a dying lift pump was the most likely cause…
Now I am struggling to solve this mystery.

patdaly

Probably isn't any clear tubing that is diesel compatible, so it would have to be a short term testing aid only.

Now that you know the last 3 owners gave up, it is a moral imperative to figure this thing out.........