After swaping out my old IP for a rebuiltI've got bigger problems. Old IP would run good for a few days then stutter and skip for a few minutes then run good for a few days etc. What Ive Done:
New fuel filter
New Injectors
New lift pump
New fuel lines
New pick up in tank
Run off a can hooked directly to Lift pump
All with no improvement. Installed a rebuilt IP just because I could not get a New one. Now the truck stumbles off idle untill about 1100 RPM and smoked blue/white smoke really heavily worse than any truck I've ever seen. I rebled injectors, new fuel filter again, checked timing and it's at 1.25mm lift, checked KSB solinoid and temp switch in intake manifold,working good. Any ideas? Oh yeah IP has been back 3 times they tell me it's OK but the last time I pulled the KSB solinoid to check it so they told me the warrenty is now voided. So I guess my choices are to find a NEW IP, Live with it running like crap and smoking or P Pump it. Thanks for ANY insight. Pump was rebuilt by a reputable well known pump shop, or so I thought.

 

Any chance you might have a bad wire (or almost bad) going to the FSS? Perhaps there is a break in the wire that shows up occasionally and causes the stumble.......

 

What makes you think it's the IP? It seems kind of obvious at first, but I'm not convinced. It's entirely possible the replacement has just exacerbated the problem, rather than saying, 'IT'S ME!!!.'
Because blue smoke is oil, which has nothing to do with the IP, and white smoke is either unburnt fuel in vapor form, (i.e. after injection) or it's coolant. So, for your smoke to have both colors I'd be thinking head gasket or oil cooler. A'course, I've been known to be wrong...

 

I should have mentioned I have had the spring/plunger pulled out from when the problem started sorry. Good thought though.

 

Had the oil analized, no glycol etc showed up, also the antifreeze shows no oil in it. I am not 100% that the IP is at fault either. I know this one runs worse than the old one. I did each repair one at a time and just ran out of things to try. Oil consumption is less than 1 quart in 5000 miles and I do have a few seeps. I have a piston lift pump and the oil analisis showed no fuel in the oil. Probably something simple that I'm overlooking. Thanks for the reply.

 

The plot thickens... less than a quart in 5k is good though. Apart from this problem I'd say your engine is in great shape! As you say, it could well be something simple. I was wondering about air in the lines, but surely that would be over the whole rpm range.

... What about timing? If it was advanced to much for low rpm, that would cause the white smoke. Oh, no that can't be it either, it only happens on days of the week that start with a 'T'.

Boy, this is a tough one. Every thing I think of, I look at what you've posted and see a reason for my idea to not be the cause. Mmm, going to have to mull this one over a while.

 

I have the timing set at 1.25mm which is stock for for the I/C engine. Non I/C engines are timed @ 1.4mm, why the change? I may bump my timing a little and see if things get better. It sure cannot hurt at this point.

 

I'm thinking something between the lift pump and the IP. A floating clog. Something trapped in the fuel heater area.

 

I did take the filter to IP line off and check for leaks and blew it out but did not remove the fuel heater. Good thought, I'll check it out. Thanks.

 

It sounds like your sucking air somewhere but you said you tried using a can of fuel by the lp, but I would check your fuel heater, make sure it isn't clogged and that the O-ring is good, along with all the fuel filter O-rings.

 

I always replace the fuel filter O rings with the filter and have a new O ring for the fuel heater because from what I've read on here they seem to be a problem sometimes. For once in my life I'm prepared!! Mine is not leaking but as far as I know it's been on there nearly 20 years. Thanks for the suggestion.