Resurrecting Clifford the big red 87 R3500

[Georgeb]

I thought I would start a thread for some of the TBI questions I may have as well as general discussion of the journey. I haven't worked on a Square much in the last 7 or 8 years since my 78 was pretty much a set it and forget it truck and I decided to start a family. Anyway I am back at it in a limited fashion with this 87 GMC. 68,000 original with some general fix it stuff already done. So far I have done the following: plugs, wires, cap, rotor, fuel filter , ball joint, alignment, exhaust, dash pad, seat, greased and oiled everything, tires radiator and hoses. I have already put it to work hauling wood and it runs pretty darn good other than a few TBI issues I haven't figured out yet. The biggest obstacle will be the body work since the floors and rockers are shot but the supports are all solid so I will be replacing the floors rather than the cab unless I find a really nice cab here in WI. HAH!

 

[Georgeb]

And then I tripped across this! I've got the itch!

 

[Georgeb]

So diving into the TBI can someone point me towards a good overview of how the engine control components work together on the TBI in this 87. I have an idle surge issue that is puzzling. It doesn't do it cold or hot but in between when it's luke warm. I have a new bosch O2 sensor and a new Delco CTS installed. The CTS helped but didn't eliminate it. I have beem through a can of carb cleaner looking for vacuum leaks but still want to replace the hoses anyway. Its not a severe surge but noticable. I also noticed while driving when in 4th gear around 25 mph it likes to inceease the engine speed and will cruise along without my foot on the gas. If I push the clutch in and remove the load from the engine it will idle back down after 3 or 4 seconds. I suspect it may be an intake leak on the inside but I can't be sure. I do have some white sludge on the oil fill cap and pcv but it could be from the truck not warming up properly. The thermostat was stuck open and the O2 sensor was busted off when I got it so it never warmed up or went into closed loop. In fact it was so full of condensation the rockers were getting rusty. The condensation is getting better and I have a close eye on the coolant level now that I have fixed all the leaks. I plan to change the oil again and see if that reduces the condensation even further. My drive to work is only 6 miles one way so it doesn't really get hot unless I take the really long way home for fun.

 

[Georgeb]

Well I was up at 4:30 this morning so I decided th put the new rear shocks on. It rides better now but I still need to do the front shocks. It rides like a Caddy with 2000 lbs in the back tho. I noticed a wet brake line so that will get added to the list as well.

 

[Georgeb]

I am starting to think about the body repair that needs to be done and contemplating color scheme. I am leaning towards red like it is with black mirrors and wheels using the stock GMC hub caps. Thoughts anyone?

 

[Georgeb]

So fighting with the idle issues on another thread.
http://www.gmsquarebody.com/forum/showthread.php?t=13089

 

[Georgeb]

I just scored the service manual, unit repair manual, fuel and emissions manual and wiring schematic for this truck with a little bit of searching. Downloaded all four of them in PDF for free!

 

[MadOgre]

I just scored the service manual, unit repair manual, fuel and emissions manual and wiring schematic for this truck with a little bit of searching. Downloaded all four of them in PDF for free!

Do you have a link to where you found all of them ? Pretty please

 

[Georgeb]

I am making progress on the brakes. Changed out the front hoses and got one side of the rear brakes done. Once I get my other parking brake cable I will do the other side and replace the line running to the back. The fuel return line is crunchy and the feed line also needs some attention.

 

[crewcab higgy]

For your idle verify your idle air control motor is working. Pull your air cleaner off and look at the iac plunger you should see it moving. You can take a t25 torq bit and adjust your idle down your iac should move and pick the idle back up.

Mine hunted for idle and was running real rich at idle I replaced every sensor an it still did it then it ended up being the computer. Also tbi can get vacuum leaks around the throttle shaft. Also I can only get a constant idle with a throttle return spring on the spring on the tbi not strong enough to completely close the plates if I come off the Gas softly.

 

[DoubleDingo]

Nice looking trucks

 

[Georgeb]

Nice looking trucks

Thanks! The red 87 is mine but the one on the trailer just caught my eye as a potential parts truck. I could use a different cab but also would have a hard time taking an almost complete truck apart when all it needs is an engine and trans.....

 

[MadOgre]

Thanks! The red 87 is mine but the one on the trailer just caught my eye as a potential parts truck. I could use a different cab but also would have a hard time taking an almost complete truck apart when all it needs is an engine and trans.....

LOL every time I see a square I start day dreaming of a frame off LOL

 

[DoubleDingo]

.......would have a hard time taking an almost complete truck apart when all it needs is an engine and trans.....

I hear that. I would rather drive it and make sure it's reliable. I don't mind a little rust as long as it's not rotting through. It's pretty dry here so rust doesn't develop quickly.

 

[Georgeb]

I figure around $500.00 in body repair panels and floor pans and I will have a solid truck. Not a show truck by any means but solid. It still has to earn its keep too... With a stay home Mom of two on a single income almost everything has to pull its own weight. Oddly that's why I bought another square. I could have spent $4000.00 more and still had a rust bucket up here. Not to mention how could you pass up a one ton with a lift gate for $950.00????