Frustrated 87 GMC owner!

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eric 87

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Location
Kentucky
First Name
Eric
Truck Year
1987
Truck Model
GMC Sierra Shortbed
Engine Size
305 tbi
Hey Ladies and Gents,
Had an 85 GMC Sierra Shortbed back in 2005 and it was rusted through in some of the normal places. Six cylinder 3 on the tree truck. Still there was something about it I liked beside it being black with red interior. It was a TRUCK. Having said that I am now the owner of an 87 GMC truck that is also a shortbed. Sharp looking and gets my wife a lot of men talking to her about it when she drives it.
BUT IT IS DRIVING ME CRAZY TO THE POINT I EITHER Crate engine swap or sell it and regret it. I HOPE THIS FORUM SAVES IT FROM SELL. The decision will be made in the next week.
I am turning 60 in a few weeks and I think I have less patience now. I wanna keep it but I have to have it be dependable!
I know just enough to get me in trouble and know to hire out work when I don't know. But there are some things I can help with and I have opinions but really try not to be an idiot to others either because it is bad enough when you need help for someone to give "nice" answers!
 

eric 87

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Location
Kentucky
First Name
Eric
Truck Year
1987
Truck Model
GMC Sierra Shortbed
Engine Size
305 tbi
Oh no....but it might keep her from being a damsel in distress ! As far as them talking....meh I don't care. lol
 

AyWoSch Motors

The Parts Guy
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Location
New Mexico
First Name
Ayden
Truck Year
1986
Truck Model
K1500 Sierra
Engine Size
350ci V8
What exactly is the main issue?
What's wrong?
Might be something easily fixed.
 

OldBlueDually

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Minnesota
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Justin
Truck Year
1976 GMC
Truck Model
C30
Engine Size
455 Olds
Welcome!

I thought the same thing as @AyWoSch Motors with "whats wrong with it" that you want to do an engine swap? Well, being a typical guy, nothing has to be wrong except you want more power, and a great V8 sound :cool:
 

1973c10

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Oregon
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Don
Truck Year
1973
Truck Model
C10
Engine Size
454
Welcome :boti:
 

WFO

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Location
Texas Panhandle
First Name
Dan
Truck Year
1986
Truck Model
K20
Engine Size
350
Welcome from the Texas Panhandle.
 

animal

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Lee
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1986
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c10 silverado
Engine Size
350ish
:welcome:
 

SirRobyn0

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Location
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First Name
Rob
Truck Year
1984
Truck Model
C20
Engine Size
305
Welcome aboard. I understand what you are saying about having less patience. I daily drive my 1984 C20, about 50 miles a day plus take it on feed runs for the farm which can be as far as 100 miles one direction. Trust me you can get that old truck to be very dependable and reliable. And we'll do the best we can to help you out.
 

Doppleganger

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OH-MI: Just like it sounds
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Chris
Truck Year
1985
Truck Model
K20
Engine Size
5.7
An 87.....my guess is the TBI has issues?

You must be registered for see images attach
 

eric 87

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Location
Kentucky
First Name
Eric
Truck Year
1987
Truck Model
GMC Sierra Shortbed
Engine Size
305 tbi
Sorry Guys. I posted my problem in the engine section as a separate thread. Not sure if that was the thing to do or not. I thought this was just the welcome wagon spot and thought I should put in a little somethin'.
Truck has new problem since me and a local shop fixed the original problem. Okay he fixed it and before that I chased every idea with the parts gun.
It would miss and sound like lady finger firecrackers when I had to accel mid pedal pulling out or kicking down into passing gear. It is 305 TBI.
All sensors have been tested correctly and/ or replaced and retested as some new ones are bad. NEW computer Map IAC Temp TPS Throttle body basically rebuilt and new distributor put in along with plug wires and plugs. The distributor had a pick up coil that lost its magnet/s. Anyway that is what fixed it. All the rest made it run better though lol.
So on the way home from the shop. It coughed or felt like a split second engine shutdown. Backing up a little in time line I have noticed and tested my alt. and battery but amp gauge will often drop from about 12 to now down to 8. If I get home and test them again even with lights blower radio etc on it tests fine.
So on the way home this cough engine feeling like it was shutting down was random but happened more often. I live 20 miles away. Within 2 miles of home it did it for a long enough period that it felt like I ran out of gas because it took a longer minute for it to bounce back. I pulled into the service station and it only held about 7 gallons to top off so that wasn't it.
When I started it up though the idle went HIGH as in 2500. I shut off and restarted and it went back down to LOW idle. Probably about 600rpm.
Next day wife tried to drive it to grocery it died at stop sign. She got it off the road in the country and started it up for the idle to go high again. She brought it back home. I took it for a 10 mile spin and it only coughed once. But I noticed when I hit the brake I lost power to the stereo for a second.
Next day I was going to attempt taking it back to shop since he has the tuning laptop and can see things I can't.
I was not 3 blocks from home on country road engine shut down. I put in neutral and cranked. Nothing. Then I lost all electrical power. Radio went dark.
I coasted to a driveway pulled in put in park cranked and nothing. NOW I know you are not supposed to do this but I pumped the pedal on a throttle body. But hey it actually hit and fired up. It of course ran rough for a minute. Then smoothed out. But I took it home. Figured I had to wait for wife to get off work to follow me IN A FORD FARM TRUCK OF MINE! How embarrassing. He can't get to it so I was spared the embarrassment.
But pulling into drive I noticed when I hit the brake pedal the amp gauge dropped from about 12 to 8 !!! It was running smooth before that getting home the 3 blocks.
I want to figure this out myself because in two weeks it has had 550$ thrown at it. The engine checks out good. I have owned it 10 months. It was a flipper that I bought it from. Compression/ valves and all look good.
I will say the work really made the 305 come to life. And it quit with me going steady at 40mph and steady going through our small rural area coming into town.
If I can't figure this out I have 3 options. Sell as is and tell new owner what is happening. But of course I will struggle to break even. I can pull the throttle body and computer out and carb intake and yet another distributor etc. That will probably cost me about 1200-1500$. I think it will solve it MAYBE unless it is electrical which I think. Mechanic also thinks it isn't fuel since it was all done and double checked.
Last option is to drop in a GM performance totally dressed engine with the accessories in place etc for about 6200$.
She lost her faith in it so we are buying her another car this weekend. Something in the 2018-2020 range. I also have a 69 firebird that I prefer to put my money in. My truck I want to be sweet and run good but not a hotrod. It is a nice shortbed pearl white with rallies. I love the truck but as stated above.....it is wearing thin.
 

eric 87

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Aug 3, 2021
Posts
89
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Location
Kentucky
First Name
Eric
Truck Year
1987
Truck Model
GMC Sierra Shortbed
Engine Size
305 tbi
An 87.....my guess is the TBI has issues?

You must be registered for see images attach
But we checked the entire fuel. Pressure reg was rebuilt with new parts. Pressure is good. When it died it also took out all power to include the stereo. I am not saying though to your idea. I am going back through all the stuff. Not sure if you saw everything I did to it but there is nothing left to replace. Okay there is that big thing under the TBI called an engine but that is the best part. It checks out fine top to bottom end. No oil usage or leaks either.
Nope this thing shut down and all electric went out as well. Like someone pulled the plug!

Love the HEE HAW lol. Dad made us watch that as kids before Mutual of Omaha's wild Kingdom. Wasn't that Sunday evening?
 

eric 87

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Posts
89
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Location
Kentucky
First Name
Eric
Truck Year
1987
Truck Model
GMC Sierra Shortbed
Engine Size
305 tbi
Your ignition switch could be faulty or not adjusted properly.
Wondering if it isn't something under the dash since the gauge dropped to 8 when I hit the brake pedal. I wonder if there is a short in the ignition wire when the brake pedal is depressed. I will have to put heat on out in garage tomorrow as it will be COLD but I intend on going over every wire I can! DO appreciate all of you good folk for giving me things to look at
 

eric 87

Full Access Member
Joined
Aug 3, 2021
Posts
89
Reaction score
26
Location
Kentucky
First Name
Eric
Truck Year
1987
Truck Model
GMC Sierra Shortbed
Engine Size
305 tbi

@ animal

@ Dave M

@ SirRobyn0

@ AyWoSch Motors

@ 1973c10

I hope you all get a chance to read over the novel I wrote with the issue at hand Above. Wanted to be sure to tell you all that has been done in two weeks fixing one problem to now have this one come up. Any thoughts would be appreciated and I will go lookin' at them one by one. Seems electrical to me since I have lost power now when it died even to the radio. But not sure where to look.
WHen I hit the brake pedal the volt gauge goes down to 8. When I let off it rises slowly to about 10. Then it will go up NEAR but not completely to 13 but I have checked it and the battery under load etc. I wonder if there is an ignition wire under the dash the pedal hits or something? When it died at first I had power still to radio but then even that died while it was still in run position. Also when I hit the brake pedal in the drive when I got it home I noticed the stereo lost power briefly. Is there a single wire that will kill the engine under the dash? I am the worst with electrical on a vehicle.

Thanks guys and Thanks for the Welcome!
 

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