I HAVE A 1999 Cadillac ESCALADE WITH A 5.7 VORTEC AND IT PULSES OR BUCKS AT HIGHWAY SPEEDS AND IT ALSO DOES NOT START VERY WELL EVER. It cranks too long before it will fire up. Truck has new spark plugs and plug wires.
There could many causes for this problem you are having on your Escalade. The computer codes would be needed scanned first of all. Next I would have the fuel pressure checked. A plugged filter or failing pump can make the truck hard to start. Lower intake manifold gaskets are another common problem on the Vortec V8. They shrink and cause a vacuum leak making the engine run very lean.
THANKS FOR RESPONSE BILL. FUEL PRESSURE IS 50LBS PLUS. TRUCK STARTS FINE WITH HOOD UP UNDER A RADIANT HEATER ON THE ENGINE OVERNIGHT.
Good ideas Bill. Fuel pressure should be closer to 60 PSI. At minimum- 55 PSI. If even 1 lb. less than 55, this engine will NOT start cold. Low fuel pressure would explain the starting problem, but maybe not the bucking at higher speeds. Look into those other things Bill talked about to see if they are related too.
The thing with the heater on the engine-
Intake manifold gaskets are a good cause for hard starting cold as well. Causes a lean condition. When the engine warms up, the gaskets expand and seal, so no more vacuum leak. The heater may be causing the gaskets to expand and seal as if the engine were running for a few minutes. This would cause a hard start, but not bucking at high speeds.
How about the temperature sending unit,could it be the culprit?
THANKS FOR THE REPLY TERRY!
Ya, it could be, but not very likely. More likely those intake manifold gaskets, or the fuel pressure is loo low. You could also try cleaning out the throttle body of any carbon. This is also a common cause of hard starting on the Cadillac and Chevy Vortec engine..
Leave comments below or see these