bad combo? 6.2 pump/6.5 injectors

[Busted]

Hey all, I've been experiencing problems that I would call as bad injectors. Really "clunky" sounding when running, lots of white/bluish smoke on startup and cold running, poor power, and vibrations that, when I first put my engine together, showed at idle (900RPMs) again around 1800, then from about 2100-2400RPMs. Now the vibration is spreading across the RPM band, smoke is getting worse--all this seems to me like injectors going south. However, it crossed my mind that perhaps the IP could be causing problems?

I had a 6.5 longblock installed in a 6.2 J code application, then turboed it with a '93 setup, and kept the original pump (can't remember the #, but it was a late 80's model HD 2829, with 5088 stamped over the original last four digits). Would a 6.2 pump make the injectors act bad due to mismatched pressure settings or fuel capacity?

[john8662]

The pressures aren't that much different.

A 6.2L mechanical pump can be used in place of a 6.5TD mechanical pump, if calibrated for the same fuel output at the specified intervals (output in cc's or MM cubed).

The physical differences of the 6.2 and 6.5 pumps come in governors used, pump head plunger size, advance piston differences.

The output of a mechanical 6.5 pump is higher than a 6.2 pump, maxed out that is. Otherwise, if calibrated the same (if in the range of a stock 6.5) you won't know the difference.

You could have a problem with bad fuel injectors, if in doubt, have them tested thourally, if allowed, watch them test them.

The pump could be failing, have a bad or non-operational advance piston, causing white smoke, poor performance.

As always, service the FUEL FILTERS as a first step in troubleshooting any fuel system problem.

J

[Busted]

I know the injectors are supposed to be different pop pressures for NA versus TD (126 bar or 142 bar) and because fluid doesn't compress, using a 6.2 pump with 6.5 injectors should effectively retard timing microscopically, correct? Because it takes slightly longer for the pump to create the higher pressure in the lines?

When you say calibrated to 6.5 specs, is that just turning up the fuel metering screw, or is there more to it than that? I turned up the screw 1/8 when I put the motor back together, but I've never seen even a hint of black smoke. As to the governor, the 6.2 should be governed higher than the 6.5 anyway.

I installed brand new Stanadyne 6.5 injectors yesterday (less than 2 hours :D) and still had really shaky idle and lots of whitish blue smoke on startup, but the rest of the rpm band seems a lot smoother. Mighta been just working the air out too. I'll play with a few other things and get back with more questions--thanks!!

[simon]

put some fuel conditioner in the fuel, go for a drive , then after warm stomp on it, i bet it will clear up for a bit. i had this condition twice.
you prob need other pump,
check for working lift pump, i think a non working LP is the cause IP goes south.