glow plug harness design?

Greg5OH

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So my starting problems became apparent after i made my glow plug harness from scratch. Basicaly I made a left hand and right hand section, and they are all fed from a 4 awg main cable, goes into a large butt connector, and splits into the two L/R connectors. however, they look like this:
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basicaly cyl 5 and 8 have very long leads, which 1 and 5 have the shortest. When its like 50-60 degrees out it coughs. i know this is a GP and not a pump issue, there is fuel, compression is good. like i said this started happenign after i finished the truck build and went to make the GP harness. I am assuming all the current goes into the first 2 or shortest leads and the rear long lead ones get little juice?
It is 4 awg into the butt connector, split into two 8 awg short leads (4") then the 8 awg into another butt, into which the 4 short ot long leads are fed into which are 10 gauge.


Should I make the harness like this? But my question is, does the last glow plug still end up with an effectively long wire?
Also, should I make a cross over at the back for it?

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Greg5OH

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Thanks. Dont know why I didnt do mine this way.

Thinking 8 gauge runner per side, with 10 or 8 gauge short runner to the connector?

I will make another one this week, im sure it will start up mint after this.
 

79jasper

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Can't remember what gauge mine was. Just some smaller amp wire I had laying around. I kept it all one size.

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Greg5OH

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for each small wire to the connector, did you just strip a part of the insulation off, wrap the wire around, then solder the joint, and E tape?
 

OLDBULL8

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I am assuming all the current goes into the first 2 or shortest leads and the rear long lead ones get little juice?

Electricity travels at 180,000 miles per second. Voltage pushes, current is resistance, at least that's what OHM says. So you could have a wire 180,000 miles long and 4000 points attached to it and in one second each 4000 points would get the same voltage in one second. The Zig Zag strip (Resistor) on the GPC relay controls the inrush current. If nothing was attached to the 4000 points, there would be no current draw. If there was a resistance (Glow Plug) connected to each 4000 points, the current draw would add up (OHM's Law). A #10 AWG copper wire has a resistance of one (1) Ohm in one (1) mile of length. So ineffect, the wire size (your sizes) from the GPC relay to the GP's is way over sufficient, #10 AWG size on each side to four (4) GP's is sufficient.
 

laserjock

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^^This. As long as all the gps have about the same resistance it won't matter. They are wired in parallel. The wire is inconsequential at the proper size.
 
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Somewhat OT, but I always wondered if anyone would be interested in making a little bit of side $$$ by fabbing up GP harnesses and selling them. Seriously, if someone were to fab up a good harness to use with the OEM system(s) with quality materials and good quality connections (solder preferred, but a good crimp would suffice), I'd be willing to pay for it. I believe these are no longer available new from Ford or IH and eBay listings for these are rare (even from U-Haul).


Just sayin'

Mike
 

laserjock

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Somewhat OT, but I always wondered if anyone would be interested in making a little bit of side $$$ by fabbing up GP harnesses and selling them. Seriously, if someone were to fab up a good harness to use with the OEM system(s) with quality materials and good quality connections (solder preferred, but a good crimp would suffice), I'd be willing to pay for it. I believe these are no longer available new from Ford or IH and eBay listings for these are rare (even from U-Haul).


Just sayin'

Mike

I've thought about this as well. The typical problem, though this harness can be a problem, is the main connector for the engine harness. A solid replacement for that connector that is plug and play would be interesting.
 

riotwarrior

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Somewhat OT, but I always wondered if anyone would be interested in making a little bit of side $$$ by fabbing up GP harnesses and selling them. Seriously, if someone were to fab up a good harness to use with the OEM system(s) with quality materials and good quality connections (solder preferred, but a good crimp would suffice), I'd be willing to pay for it. I believe these are no longer available new from Ford or IH and eBay listings for these are rare (even from U-Haul).


Just sayin'

Mike

I am actually considering this for my own rig...crimp solder heat shrink entire harness. If I do uou can be assured I will do a tech 101 on it.

Wont be cheap though for certain...not at all.

E D I T

Going to mod my current one for sake of expiditing the process. Then if works ok maybe revamp the whole thing. It is already modified as the gp controller was moved atop pass valve cover similar to factory turbo.

Once I am done will get pics...
 

franklin2

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The glowplug controller is calibrated with the original glowplug harness in place. Anything you do to make it "better" is going to throw the glowplug controller off, and it's not going to be able to judge the amount of current flowing through the plugs, since now you have changed everything around. So if the controller does not glow the plugs the proper time after your harness upgrade, the harness is going to be at fault. If you think the factory did a crappy job building the harness undersized, you are going to have to live with it if you use the original controller.
 

OLDBULL8

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I think I still have two factory GP harnesses left, check the Market place. Just sold one to IDIoit, hope he likes it.

IH PN is 1807648C94 made in the USA, cheap for only $150, that's IH price,not mine.
 

Wvdirtroad

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When I redid mine my factory glow plug ends were all melted down. I believe mine feeds from 8 gauge off the main strand to the plug. I found some nice butt connectors that have the crimp connector inside it and then a plastic coating over that that extends back up the wire about a half inch and is lined with adhesive. I heat shrank the connectors to the wire and then added extra heat shrink over it. Connections are almost cool to the touch now when running the plugs.
 

Runningaford

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The calibration aspect is interesting regarding the controller. It's been a long time since I used electrical theory, and did voltage drop calculations, but considering the size wire used, there shouldn't be any. 10 awg good for +/- 30 amps, 8 awg good for 40 +/- amps, 6 awg good for 50 +/- amps, and the 4 awg good for at least another 10; all depends on the type of insulation of course.

If you really want to do voltage drop calcs. it's vd= 2*k*i*d/circular mils of conductor.... K, is constant ohms, copper is around 12.9, i is your amps, and d is distance. You'd have to figure the amps needed per glow plug for that calc.

BUT, I don't think that's anywhere near necessary, but if the controller is calibrated for the differing resistances, then to change the length, or gauge of the conductor could cause issues.:D
 
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