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92 c1500 problem
Thread Starter
Staging Lane
Joined: Sep 2008
Posts: 76
Likes: 0
From: Claxton, GA
92 c1500 problem I could use some help guys. My truck is surging in and out like the fuel is cut off or something if i floor it from a dead stop. I have replaced fuel pump, fuel filter and distributor cap and rotor. Im attaching a picture of some rigging the guy before me did. could you tell me what the think is i circled? Could it have anything to do with the surging?[IMG]
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[/IMG] I have a 1990 C1500 so that looks familiar. If I remember correctly, what you've circled is the ESC Module (Electronic Spark Control) and also the MAP sensor with the vacuum line attached. The ESC is connected to the knock sensor and provides input to the computer. You could check your timing and see if it's fluctuating. Did you set the initial timing? I believe it's supposed to be at 0°. Where does the red wire lead to that's spliced into the pink/blk wire? +12v off the battery?
Edit: As stuart4185 mentioned, probably not the ideal forum, but if you want, I can PM you a copy of the wiring diagram I have for a 1990.
Edit: As stuart4185 mentioned, probably not the ideal forum, but if you want, I can PM you a copy of the wiring diagram I have for a 1990.
Thread Starter
Staging Lane
Joined: Sep 2008
Posts: 76
Likes: 0
From: Claxton, GA
no its some rigging the guy did. It has a aligator clip on the other end and if you hook it to ac switch the ac compressor comes on? Some people. lol. So with all that rigging going on it could have something to do with it stalling like that in a hard pull.
Launching!
Joined: Jan 2012
Posts: 211
Likes: 0
From: baltimore maryland
well, i have never seen that before lol, yes that could cause it to run bad, but with all that corrosion, i would suspect a head gasket leaking or it was flooded under water at one point. what color is the oil? antifreeze?
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Verdad Gallardo 4 looks correct... Check out the diagram, middle-left:
http://www.ih8mud.com/tech/tbi/wireTBI-1990b.gif
http://www.ih8mud.com/tech/tbi/wireTBI-1990b.gif
I have an 88 K1500 that I just swapped in a 350 in place of the original 305. Looks like the previous owner tapped into the 12V hot wire going to the ESC module to power the AC compressor clutch. I'd guess that the ESC module is intermittently losing power, which will cause your timing to jump all around, which is probably causing the surge. Repair that wire and see if the problem goes away.
You can check the timing with a regular old timing light. The correct way to do it is to disconnect the set-timing connector, located under the relay cover on the passenger side firewall. You are looking for a tan wire with a black stripe. Start the truck, then unplug this connector, the engine will probably start to run rough and a check engine light will be set. This is normal. Check the timing with the light, it should be at 0 deg. If it's not, loosen the hold-down clamp on the distributor and rotate it slightly until it's 0. Then shut the engine off, disconnect the battery to clear the code, and reconnect the set-timing plug. After all of that, start it back up, and check the timing at idle. It should be anywhere from 16 to 18 deg with everything working properly. The quick and dirty way to do it is to just set the timing at 16 or 18 deg and not worry about the set-timing connector. Either way, it will give you an indication of where your timing is.
It could be the pump or more likely it's the fuel pressure regulator spring. Check out the schematic toward the bottom of this page: http://www.chevythunder.com/gm_throt...ction_pg_1.htm
I rebuilt a TBI throttle body for my new motor that came out of the junk yard. The regulator spring was actually broken in two when I took it apart. If yours is broken, it could be bouncing around causing erratic fuel pressure, which could be the cause of the surge. You can get a rebuild kit from Advance for the TBI, but you'll have to get a spring from either a junk yard or online somewhere. The TBI unit can be rebuilt in less than an hour, there's not much to it.
I rebuilt a TBI throttle body for my new motor that came out of the junk yard. The regulator spring was actually broken in two when I took it apart. If yours is broken, it could be bouncing around causing erratic fuel pressure, which could be the cause of the surge. You can get a rebuild kit from Advance for the TBI, but you'll have to get a spring from either a junk yard or online somewhere. The TBI unit can be rebuilt in less than an hour, there's not much to it.
Try some guys that work on these things every day. http://tahoeyukonforum.com/forum/forumdisplay.php?f=35
They are a little slow but some of these guys really know their stuff.
They are a little slow but some of these guys really know their stuff.