Whats you gas mileage on your squarebody truck?

[davbell22602]

Thats the problem, He has toght you to be a parts changer, and not a Mechanic. Mechanics Diagnose before throwing parts at the problem.
With OBD 2, you should be able to at least find the offending cylinder(s) and have a general area to start.. If you dont have a scanner, and since you have headers now, just take a IR temp gun, and get readings from each header tube, write them down, and report back.
Im sorry guys, I just cant let this go. selling a truck for not running right is ********. Even though I have thought about it myself, I could never go through with it.
It would be cool for Dave to get a Square, but if his gmt400 is runing right, he may be able to get more money for it.
****...maybe we need a Help Dave thread.
Not trying to Put you down buddy, I understand, we all have our qwerks. Heresbwhat you can do now, since you have MAF....go out, and inspectsbyour intake tube between the throttle body, and the maf, make sure ther ar NO rips or hols in it, then make sure its properly installed, and the clamps are tight. Have you ever had your EGR valve off?

No I dont have a OBDII scantool. I scanned at and everything checked out within spec. No tears or rips in the MAF tube either. Dont have a temp gun either. Someone did suggest that the dizzy gear might be worn and throwing in and out time. But I dont see how on a 137K truck though.

 

[Stroked]

My brother has a 1991 Chevy with 90,000 miles on it and his dizzy was completely shot. Granted it is 6 years older, but I'm just saying don't completely rule it out.

 

[davbell22602]

My brother has a 1991 Chevy with 90,000 miles on it and his dizzy was completely shot. Granted it is 6 years older, but I'm just saying don't completely rule it out.

I know. I thought vortec supposed to get better mpg than the 88-95 TBI?

 

[Stroked]

They supposedly do. My 1990 K1500 ext cab got 18-20 mpg on the highway

 

[Jims86]

They supposedly do. My 1990 K1500 ext cab got 18-20 mpg on the highway

I have heard as good as 23 with some TBI's....thats with tuning though. Dave, Go out and pull the dist cap off, grab the rotor, and try to move it side to side, and then check up and down motion, if there is, try to measure....and make sure the vent holes in the bottom of the distributor are clear....might as well look at the terminals in the cap. Maybe hit the headers with a spot of white paint on each tube. You are looking for the coolest running cylinder.

 

[davbell22602]

I have heard as good as 23 with some TBI's....thats with tuning though. Dave, Go out and pull the dist cap off, grab the rotor, and try to move it side to side, and then check up and down motion, if there is, try to measure....and make sure the vent holes in the bottom of the distributor are clear....might as well look at the terminals in the cap. Maybe hit the headers with a spot of white paint on each tube. You are looking for the coolest running cylinder.

I guess a paint pen will work for marking the header tubes? I'm only getting 12-16mpg for highway mileage.

 

[Jims86]

I guess a paint pen will work for marking the header tubes? I'm only getting 12-16mpg for highway mileage.

Yep, that should work...mark the tubes, let it dry, then run thentruck long enough for the paint to start turning brown, the marks that are lightest, are the problem cylinders.
TBI usually get a little better MPG and low end torque, due to the swirl ramps in the intake ports, they are **** heads for high performance though.

 

[davbell22602]

I did a compression check back in January.

Here's results:

#1 - 200 then dropped to 195 within 2-3 seconds
#3 - 200 then dropped to 195 within 2-3 seconds
#5 - 200 then dropped to 195 within 2-3 seconds
#7 - 195 no bleed off
#2 - 195 no bleed off
#4 - 200 then dropped to 195 within 5 seconds
#6 - 195 no bleed off
#8 - 195 then dropped to 190 within 2-3 seconds

 

[Jims86]

I did a compression check back in January.

Here's results:

#1 - 200 then dropped to 195 within 2-3 seconds
#3 - 200 then dropped to 195 within 2-3 seconds
#5 - 200 then dropped to 195 within 2-3 seconds
#7 - 195 no bleed off
#2 - 195 no bleed off
#4 - 200 then dropped to 195 within 5 seconds
#6 - 195 no bleed off
#8 - 195 then dropped to 190 within 2-3 seconds

Compression can be good, but if the 2 other things, fuel,and spark are not right, your going to get a miss...Have your ever decarbonized the top end of the engine using Sea Foam, or the GM top end engine cleaner?

 

[89Suburban]

This is my last fillup of city mileage from my 1988 suburban. I have about 6000 dollars in just the drive train swap though.

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^^^What app is that?


I never did my mileage yet, towing that boat around town every night I am sure it aint all that great. I will have to figure it out.

 

[davbell22602]

Compression can be good, but if the 2 other things, fuel,and spark are not right, your going to get a miss...Have your ever decarbonized the top end of the engine using Sea Foam, or the GM top end engine cleaner?

I did that BG engine top clean 3,000- 6,000 miles ago when I was in the auto class.

 

[Jims86]

I did that BG engine top clean 3,000- 6,000 miles ago when I was in the auto class.

Ok. Good.

 

[wildcatjason]

^^^What app is that?


I never did my mileage yet, towing that boat around town every night I am sure it aint all that great. I will have to figure it out.

It's car minder for iPhone. Not sure if it is a droid app too. I'd like to find out my straight highway mileage for that thing, but my first highway trip from Wichita to OKC and back just put me down to over 3/8 of a tank.

 

[foamypirate]

I got about 12 around town and 17.5 or so highway with 700R4/3.08s. Lugged the hell out of it around town with the tall gear.

 

[HotRodPC]

How've I missed this thread? I'd rock a VW Rabbit Truck, espeicially a Diesel. I know a guy who had one. He got pissed because it fell just short of 500,000 miles and wanted 500,000 out of it. He drove it for years and years and years. He was an over the road truck driver and used it for his back and forth to his big truck, and his big truck maintenance part chaser, along with his wife drove it to take their son back and forth to work. I seen it with some pretty heavy loads on it. Like 13 speed Eaton Fuller transmissions.