The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post

79vette · 03-30-2022, 01:08 PM

Can anyone give me some advice on troubleshooting poor fuel mileage and an intermittent rough idle?

I just changed the fluids when I bought it and it had not been maintained in awhile, so I am sure it needs some work. I'm planning do do cap/coil/rotor/plugs/wires, check the air filter, fuel filter (if I can find it), check for vacuum leaks, verify the timing, check compression, and also check for a fuel leak. Any other suggestions? How can I verify the TBI unit is working right?

The truck always starts, makes decent power/tows well, but gets 6-7 mpg. The crane isn't THAT heavy, and I would expect at least 10. For comparison my carbed Blazer got 14 on 33in mud tires, 4in lift and an auto trans.

03-30-2022, 01:08 PM	#25
79vette Registered User Join Date: Jan 2017 Location: Sandy, UT Posts: 191	Re: Square Body Crane Truck Can anyone give me some advice on troubleshooting poor fuel mileage and an intermittent rough idle? I just changed the fluids when I bought it and it had not been maintained in awhile, so I am sure it needs some work. I'm planning do do cap/coil/rotor/plugs/wires, check the air filter, fuel filter (if I can find it), check for vacuum leaks, verify the timing, check compression, and also check for a fuel leak. Any other suggestions? How can I verify the TBI unit is working right? The truck always starts, makes decent power/tows well, but gets 6-7 mpg. The crane isn't THAT heavy, and I would expect at least 10. For comparison my carbed Blazer got 14 on 33in mud tires, 4in lift and an auto trans. __________________ 1988 "Crane Truck" C30 - 350, SM465, with a 15' knuckle crane - thread 1986 M1009 - 6.2 Diesel, SM465, 2 speed aux trans, NP205 - thread 1979 Corvette - 350 T5 1977 Jimmy - 350, TH400, NP203 1982 Blazer - 350, 700R4, NP208 - Totalled, now a parts truck Scratch built 16' flatbed trailer - thread Last edited by 79vette; 03-30-2022 at 05:54 PM.