73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Electrical => Topic started by: rcollamore on April 10, 2016, 06:45:05 pm
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Ok so I have no idea what the name of this wire harness is it comes down from the my engine then splits into 3 separate wires looks like 2 of the wires goes to the starter then the 3rd goes to this white rubber tip that is sticking out from the bottom of the engine which this 3rd wire which is a male end connects to the female rubber tip.
I have to replace these wires because they are so corroded and that the 3rd wire I was talking about half of the plastic is gone so it barely says connected to the white tip.
I hope i was able to explain it the best let me know if you guys needs pics not a problem I can get them just been raining all day so I haven't had a chance to get a pic.
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Year/make/model?
Post a couple of pics.
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Ya sorry about that probably help if I gave that info 1987 Chevy Suburban
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That thing sticking out of the cylinder block is the knock sensor. You can buy a pigtail for it. The other wires are fusible links
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Ok thank you! If that is unplug will make it impossible to for the Chevy to turn over?
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No however your burned up fusible links will.
http://forum.73-87chevytrucks.com/smforum/index.php?topic=11972.0
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Gotcha and you can't buy l the fusible links and the wire for knock sensor and just remove the crap and add the new wiring
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Awesome link thank you!! The only reason I am asking about if I could buy the fusible links wire is because I don't own a soldering tool
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I know a soldered joint is more reliable but I don't see why a butt connector wouldn't work. But a soldering iron isn't too expensive $30
http://forum.73-87chevytrucks.com/smforum/index.php?topic=28681.msg239369#msg239369
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Well that's what's trying to go for is use butt connectors on those wire and buy the fusible links I don't mind buying a soldering iron i just wanted to find fusible links premade
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Does any know what size those fusible links are?
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Hard for me to guess. But if I had to it might be 12&14 ga. But might be 14&16
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As a rule of thumb I believe, and BD will probably correct me on this if I'm wrong. Fusible links are generally 2 wires sizes smaller than the size of the wire for the circuit they protect and they are made of different materials (I think). So a 12 gauge wire might be protected by a 16 gauge fusible link.
Or maybe it's 1 size smaller, pretty sure it's 1 or 2 sizes smaller. I'm not an electrical master technician.
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With some notable exceptions on medium duty GM trucks, a fusible link is always 6" long and 4 wire gauges numerically higher than the wire it protects. So, a 10-gauge wire will be protected by a 6" long, 14-gauge fusible link; a 12-gauge wire will be protected by a 6" long, 16-gauge fusible link; a 14-gauge wire will be protected by a 6" long, 18-gauge fusible link; and a 16-gauge wire will be protected by a 6" long, 20-gauge fusible link. Get the idea?
According to the 1987 factory GM wiring manual, the two red wires in the image you posted are 3 mm2 (which is a 12-gauge wire protected by a 16-gauge link) and 1 mm2 (which is a 16-gauge wire protected by a 20-gauge link), respectively. However, carefully inspect the wires to verify the actual gauge, because 16-gauge seems small and maybe a typographic error in the manual.
The pigtail for the knock sensor is an AC Delco PT308 (imaged below). The knock sensor lead is 16-gauge dark blue with SXL insulation. You should shield the wiring from excess exhaust heat and replace the heat shield for the starter if it is missing.
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Told ya lol. I was way off.
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You guys are awesome!!! Well I changed out those wires and knock sensor but no luck with the engine starting.
I do see the issue though no fuel coming from the injectors that could be a problem lol ugh man always something
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Do you hear the fuel pump run for a couple of seconds immediately after switching the ignition on? Check the ECM I and ECM B fuses. Check the ECM ground connections at the thermostat and back of the right cylinder head. Make sure that the distributor connectors are completely plugged in and that no pins are bent over. Check the fuel pressure.
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Ya the fuel pump turns on for a couple minutes when turned on. All the fuses are good.
I did find that there is no fuel in the fuel lines period none at all lol.
So I am guessing it's the Fuel Pressure Regulator am
I right?
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no fuel in the fuel line, sure you got fuel in the tank? made that mistake once lol
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Lol ya I made sure I had a enough before I posted this question lol
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Check for a pinched fuel line and/or totally plugged f/filter. If it has dual tanks the selector valve maybe sticking or plumbed to the wrong tank.
Substitute a pressure gauge for the f/filter, start the engine and take a measurement; pinch off the return line leading back to the tank and take another measurement. What are the pressure readings?
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I have checked the fuel lines for anything pinched nothing there either I have already changed out the fuel filter when I did that there was no fuel even coming out of the lines when I removed the old filter.
I will have to get a fuel pressure reading gauge since I don't have one and to rent one autozone wants a 150$ deposit lol
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It could be a faulty or dislodged pump in the tank, or a plugged pickup. When you replaced the fuel filter, did you notice whether the old filter contained any sediment?
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No I didn't notice anything out of the ordinary. I have tested everything minus the fuel pressure gauge test.
There is no fuel coming through the lines at all pretty much bone dry lol when I pour fuel into the carburetor it will start but of course die when its out of fuel.
I have ran air through the lines to see if there was a clog I wasn't able to find a clog when I did it.
So I assuming that it's the fuel pressure regulator
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theres a little rubber line that attaches the fuel pump to the sending unit it could be busted and all the fuel is pouring out the side back into the tank
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Ok I think I would see that because my gas tank sits in back like this while I try to find someone to build me a custom tank or just mount this tank.
So that's why the gas tank is currently like this.
It helps though because I can see everything on the tank and accessing areas are a lot eas
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Here is the pic I didn't get to attach to my last post
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you wouldnt see it cause its in the tank itself. you have to take the sending unit out to see it
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I misread your post sorry it's a brand new fuel pump and that rubber hose was replaced in the process.
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Well, the picture you've painted suggests either a faulty pump or improper installation. With the pump running, can you hear fuel flowing inside the tank? If you pull the 3/8" fuel line off of the fitting on the fuel tank pickup and cycle the pump for 1 second, will any fuel pump into a can or rag?
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No I don't hear any fuel flowing I hear the fuel pump then on and then after a sec or two it shuts off.
Ya I've done that test too no fuel comes out at all.
And the the fuel in the gas tank is covering half of the fuel pump it's self so I think there's enough fuel.
So it can't be the fuel pressure regulator?
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Look at it from this angle. If fuel is not exiting the pump with the fuel line completely unplugged and open (in other words, the fuel pressure regulator is effectively removed from the system), how could the pressure regulator restrict fuel flow? The problem is inside the tank.
The pressure regulator has no effect and cannot be tested until fuel is actually delivered and the system is pressurized.
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Gotcha well then it has to do with the fuel pump itself prob a faulty pump I got. Since the dang thing turns on and no fuel comes out
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make sure the output line on the sending unit isnt clogged
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Well seemed like everyone was right in some way, the issue was the debris inside of the gas tank which clogged up the new fuel pump. So I had to drain the fuel clean out the tank( upgrading to a custom fuel cell when I find the right person to do and doesn't try to charge me a arm and a leg) replaced the fuel pump added fuel and the suburban started right up! So glad it's finally done and fixed.
Thank you everyone for your help.
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