Engine/Transmission (1994 - 1998) '95 problem still not resolved. HELP!

[DKRCH]

My 95 12 valve has 100,000 miles and has had no problems with the engine until now. I previously listed the problem and got no help. I wondering if this problem is so unique that no one has an answer. The problem is white smoke when I hit 2600-2700 RPM and the engine starts stumbling. (The engine would always go to 3000 RPM before govenor kicked in and no white smoke until now) This white smoke is burn your eyes smells like unburnt diesel smoke. The compression is normal the injectors are normal, the timing is normal, the valves are adjusted normal, the boost is 22 lbs, the EGT is normal. The only changes are 215 hp injectors installed years ago.

 

[AEdelheit]

I would suspect a possible air leak into the fuel lines between the fuel filter and pump, or a clog in the banjo fittings between the filter and pump. My logic being its running out of fuel during higher flow demands and the filter housing should act like a small reservoir so it should not run out easily which makes me think its between the filter housing and pump. Ive seen it before at work where a banjo gets clogged, allows enough fuel for low RPM's but not enough for higher fuel demands, or it starts sucking air through a very small pinhole leak otherwise unnoticeable. Good luck!

 

[LandShark]

You state that the only mods made to your truck are 215 injectors. I don't know of any 95's that will hit 3000rpm without a GSK mod. What aren't you telling us?

Fill out your signature so we know what truck you have. With the limited info you have given us, I would make a wild guess and say a possible air leak in the air intake system.

 

[snappy]

Change the fuel filter and overflow valve in the P7100.

 

[cerberusiam]

Timing gear slipped on the pump shaft. Retime the pump and see if that cures it.

 

[SRath]

Is that just a press-fit with no keyway?

 

[mwilson]

Another vote for a fuel line issue, I'd check that first.



Mike.

 

[mwilson]

Is that just a press-fit with no keyway?

Correct, no keyway.



Mike.

 

[SRath]

Certainly sounds like a good place to start. The strong smell of unburned diesel mitigates towards a fuel timing problem (e. g. fuel is being delivered, but not burned). I wouldn't think a lean condition due to an airleak would be the same.



He says "the timing is normal". Based on what?



And I would still like to know the answer to LandShark's question, too. Please note I have no useful expertise or suggestions, but I am very curious as to what the experienced brain trust here comes up with to file away for future personal reference should I ever find myself with a similar problem.

 

[cerberusiam]

Black smoke is lack of air.



White smoke is late injection timing, always.



A diesel really has no lean condition like a gasser because the fuel is injected not mixed then metered. A lean fuel mixture just limits rpm and asl ong as its injected at the right time it will run fine.



Leaks in the fuel system after the LP are noticeable as diesel all over under the hood. If the LP is putting out full flow you can spray as much fuel under the hood as is used to run the engine and see no performance loss.



Leaks between the LP and tank show as hard starting and lack of power. Normally on a jerk pump when it runs out of fuel it runs out of rpm and quits revving. No smoke just no go.



The gear on the IP is a press fit with no key way and they slip. Since the P-pump has no dynamic timing a small slip will limit the rpm it will rev to without showing white smoke which is unburned fuel. It hits a point where the fuel is just being injectoed too late and it noses overs, frequently back fires in the exhaust, and throw lots of white smelly smoke.



With white smoke always look at injection timing first. Then look at fuel delivery and then possibly something in the governor sticking.



With the boost a 22 psi and no mention of a bigger turbo, boost leaks are usually not an problem. Since the engine runs good till about 26-2700 its doubtful fuel supply is an issue.



As always, an internet diagnosis is only as good as the given info.

 

[SRath]

Black smoke is lack of air.



White smoke is late injection timing, always.

Which one means they have a new Pope?



Seriously, that is an excellent nutshell explanation and troubleshooting guide, cerberusiam!

 

[cerberusiam]

Black smoke is lack of air.



White smoke is late injection timing, or a new Pope depending on the context.

Fixed it.

 

[DKRCH]

Timing was set to factory spec. Still have problem. Could I be floating a valve? Since it runs rough during this time of white smoke.

 

[GAmes]

Is this a problem only when the engine is at operting temp or all the time, even when cold? If it only does it while at operating temp does it idle badly? If so, try pouring a pan of ice water over the IP while it is idling and see if the idle improves. That would point to a common problem (IIRC, delivery valves) in the '96s and requires an IP overhaul.

 

[Draught]

I have a 95 did the same thing stopped up fuel filters.

 

[JMalik]

I am also surprised that you can produce 2700 to 3000rpm at 20psi boost. Means you are putting out alot of horse power. If you mean the same RPM under no load and low boost it is normal. White smoke tends to mean you are running lean. The 215HP injectors with your 260HP P7100 injection pump would demand significantly more fuel than your OEM injectors thereby stressing your fuel delivery system. Your fuel pump does have some problems with air leaks. You now have enough run time to have problems with the fuel heater. It tends to fry its connector and produce air leaks. You can easily take it off, remove the 8mm adapter and reinstall the pump fuel filter/bowl. See if this helps. If so you might want to check the fuel pump check valves. If air gets into the system the check valves can beat themselves to death and come apart yet still remain somewhat functional. The TDR has a really great writeup on how to deal with changing the pump. Its located on the main page in the Buyers Guide. Genos Garage can provide you with both the pump and the heater. Both the heater and the pump died on me but they did very slightly slow down startup. Usually my engine starts on the first turn. The startup delay was not noticable if I did a short crank and then it started immediately on the second crank first turn. My pump heater had fried its heater connector, beat it's checks valves to death and developed some air leaks with the manual pump button O rings as well as the heater connector. Power under full load(10K 5th wheel)was compromised but not noticable otherwise.

 

[GAmes]

I pretty much agree with JMalik, except about running lean. Diesels do not run "lean", the ratio of air to fuel is constantly changing. A fuel shortage would result in decreased power, and the exhaust would be colorless if all the fuel is being burned. The white smoke could be a timing issue, but since it only does it at certain RPMs I doubt it. Did you ever try the ice water over the IP trick?