New To this Forum, Bought a 1987 C20..

[RcClockman]

Hello Forum!  I bought My stepdad a 1987 R20 Single cab, Utility bed truck, with Ladder Rack, Locking side cabinets, for his Plumbing Business.    It has the Fuel Injected 350, with A 4:10 Rear end and 3 speed TH400 I believe,.. Did a full Tune-up on it , including, Air Filter/Plugs/Wires/Cap/rotor/Computer water temp sensor/new 195 t-stat/Waterneck/ os sensor/rad flush/… Engine runs very stong and has about a 135PSI COmpression average..  My question is this... It Only Gets 8 MPG.. Is this what I can expect?   Is there anything else I can Do to Improve this...    It is a California Truck and has all Smog equipment hooked up including Pump...  It just passed smoq Inspection..Thanks for any help and suggestions...

[Stewart G Griffin]

Watch:

https://www.youtube.com/watch?v=qw6HG8-O008

[zieg85]

With easy driving and some timing you should be able to get higher mpg.  I got 12-13 out of the same combo but mine being a C30

[RcClockman]

On my truck, the spec is for 0 Degrees timing... as the computer advances the timing..

[Rapid Roy]

Welcome

[Irish_Alley]

did you set timing at 0° with the little est disconnected?

[RcClockman]

Yes I Did..

[Irish_Alley]

i have a 91 v3500 crew cab. it has OD but pretty much the same thing as you. i got 12 MPGs with the gas motor, the biggest thing is not flooring it all over and keeping the speed down. the non OD trans you should still be at least 10 MPGs IMO

[VileZambonie]

Hello Forum!  I bought My stepdad a 1987 C20 Single cab, Utility bed truck, with Ladder Rack, Locking side cabinets, for his Plumbing Business.    It has the Fuel Injected 350, with A 4:10 Rear end and 3 speed TH400 I believe,.. Did a full Tune-up on it , including, Air Filter/Plugs/Wires/Cap/rotor/Computer water temp sensor/new 195 t-stat/Waterneck/ os sensor/rad flush/… Engine runs very stong and has about a 135PSI COmpression average..  My question is this... It Only Gets 8 MPG.. Is this what I can expect?   Is there anything else I can Do to Improve this...    It is a California Truck and has all Smog equipment hooked up including Pump...  It just passed smoq Inspection..Thanks for any help and suggestions...

That would be an R20. If it is properly tuned then your best bet is an overdrive swap and a custom tune.

[RcClockman]

thanks for the sugestions...it just smells rich as   its running, but the plugs are not fouled and look good..

[VileZambonie]

Do you have a scan tool?

[RcClockman]

if it was running rich. it would throw a light and store a code right? 

[VileZambonie]

Not necessarily. Garbage in = Garbage out. You need a scan tool to analyze your data otherwise you will never be able to do anything other than guess

[RcClockman]

Put on a New Map Sensor (California version) now getting 11 MPG whoo Hoo!!

[RcClockman]

Also, Have very Loud Popping noises coming from the Heater Core when the engine is Hot and when I come to a stop.. We solved the issue by bypassing the heater core... My mechanic say the fix to it is to put in a very small. mabee 1/4 inch size restrictor tube in the heater Hose lines to reduce the amount of flow through the heater core... Anybody heard of this??