I took my 91 GMC Sonoma (2.8L V6) in for a check up because my "service engine soon" light has been coming on routinely when I drive over 60 mph. I believe a code 47 came up, but basically the shop said the code is for detection of raw fuel. They want to take apart the throttle body to see if anything is wrong, and if they find nothing, look at the injector. Also, this started about one week after I got my truck smog'd and a cadilac converter was installed and my fuel mileage droped from about 20mpg to 17mpg.

SOURCE: 1996 GMC Sierra 1500 truck fuel problem

Have you check the injector relay or maybe a fuse for injectors.

SOURCE: Truck losing power and service engine soon light on

Like to other guy said, give it a tuneup. Also try SEAFOAM to clean carb up of slug. Also check to make sure the butter fly for the choke has not come loose, causing it the choke it down. Failed choke pull-off.

SOURCE: engine won't idle,

ok code 32 is the EGR (exhaust gas recirculation) this does not mean that the EGR valve is bad right off, check it and see if it is stuck in the open position, remove the vacuum line see if it moves, it should not. It is supposed to open at highway speed to recirculate exhaust gases and burn them, if the valve is stuck open the engine will not idle because it upsets the air mixture too much, if you remove the valve and see its open, then replace it.

SOURCE: 91 sonoma fuel problems

pump works when supplying power from the keys or other source some is it a new pump ? if is return for a exchange. if not even tho the pump may work when you power it with the key there might not be enough pressure from the pump to push enough fuel to the engine so i advise replacing it

Marvin

• 85242 Answers
• Posted on Sep 29, 2009

SOURCE: 1996 1500 Silverado V6 4.3 gas mileage.

for better freeway mileage a low back pressure exhaust will help, also run tires at max pressure, this is around 45 PSI, in town there is little you can do.

Testimonial: "Thanks for the advice, I didn't know about the low back pressure exhaust system, I'll try it out."