no tach, check engine lite, black smoke...

[Northern Wrangler 6.2]

Hey group. I just picked up a 95 6.5 Turbo.....driving it home, there's no tach, check engine lite is on, lots of smoke, hard on fuel.....what to look for ?

Any info will help.

Kev

[More Power]

The tach signal is derived from the alternator. Is it generating correct voltage? If not, this might explain the other problems you mentioned.

Jim

[MTTwister]

Wouldn't be something as simple as a missing, or slipping fan belt? ( drives the alternator and the vacuum pump for the turbo) Did it overheat?

[93_Burrito]

Kev,

Lots of smoke and poor fuel mileage indicates a lack of turbo boost. I had the same problem with my recently acquired '95 Tahoe 6.5L TD. I also had a "check engine" light, a code 35 which has to do with the EGR system. I solved my issues by installing a TurboMaster to replace the factory boost control system, and replaced the factory 'S' computer chip with an 'F', which doesn't look for EGR equipment. While removing the factory boost control stuff, I discovered the wastegate diaphragm was bad. For the factory setup, you want to inspect the vacuum pump, vacuum hoses, wastegate solenoid, diaphragm... I prefer a little simplicity. Just filled my truck up since the TurboMaster was installed, and I gained 2 mpg in city driving.

I also had a problem with the speedometer becoming erratic, shooting 30 mph faster than actual speed, then dropping 10 mph below before finally settling back where it should be. My tach would also either freeze at a particular RPM or it would just quit like you turned the truck off. The trans would get stuck in limp mode (2nd gear). The gear select light in the dash (which tells you what gear the trans is in) would go out. Replacing the ignition switch took care of that.