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Bypassing the oil pressure switch for fuel pump wiring? by Threedog
Started on: 05-17-2015 04:04 PM
Replies: 9 (517 views)
Last post by: Threedog on 05-19-2015 09:30 PM
Threedog
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Report this Post05-17-2015 04:04 PM Click Here to See the Profile for ThreedogClick Here to Email ThreedogSend a Private Message to ThreedogEdit/Delete MessageReply w/QuoteDirect Link to This Post
This is a 96 3800 swap in an 86 Fiero w/ a manual

I like the idea of just carrying an extra fuel pump relay with me in the car in case mine goes out, how to I set up wiring for a bypass of the oil pressure switch?

Currently I have coming out of my Fuel pump relay:
-PIN A(Dr Grn) going to the ECM PIN 8(blue)
-PIN B(Tan/white) going to C203 PIN L
-PIN C(Black/white) going to a chassis ground(linking up with the ground from C500 and C203)
-PIN D(Oange/black) going to C203 PIN B

Currently that its all I have done, I also have an extra org/black wire, is there anything else I need to do?
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phonedawgz
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Report this Post05-17-2015 05:43 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Nope - Other than wack off the extra Orange'/Black wire.

[This message has been edited by phonedawgz (edited 05-17-2015).]

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Threedog
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Report this Post05-17-2015 06:21 PM Click Here to See the Profile for ThreedogClick Here to Email ThreedogSend a Private Message to ThreedogEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by phonedawgz:

Nope - Other than wack off the extra Orange'/Black wire.



Once again, Phonedawgz to the rescue....

Another quick question: My donor harness was supposed to have black/white wires for PCM grounds, but two of them seem to be tan/white(they are joined together from the factory). Can I just put all four of those ground wires together into a wire of the same size or do I need a thicker gauge to get it to the peg?

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phonedawgz
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Report this Post05-17-2015 06:38 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
GM used Tan and sometimes Tan/White for the grounds that ran to the ECM for the injectors.

If you do splice the 4 wires together the wire that runs from the splice to the ground lug should be a thicker wire.
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Threedog
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Report this Post05-17-2015 07:46 PM Click Here to See the Profile for ThreedogClick Here to Email ThreedogSend a Private Message to ThreedogEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by phonedawgz:

GM used Tan and sometimes Tan/White for the grounds that ran to the ECM for the injectors.

If you do splice the 4 wires together the wire that runs from the splice to the ground lug should be a thicker wire.



Sigh, this is gave me one(hopefully last) question. The wire coming from c203 PIN J and K (injector wires power and all the other sensor power, respectively) is not a larger gauge than the the wires feeding into the splices.

As in:
Wire coming from PIN J is the same AWG as the wires that go to each injector(post splice). Should it be larger?


Could this cause not enough power to get to the injectors? Or am I at a pretty big fire risk there?

[This message has been edited by Threedog (edited 05-17-2015).]

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phonedawgz
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Report this Post05-17-2015 08:54 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
It is hard to gauge the gauge of the wires. (pun intended)

The Fiero wiring uses PVC for insulation. The 3800 wiring is crosslinked TXL. So things end up changing. The same gauge wire in TXL is much smaller overall than the same gauge in PVC. The second is that the insulation can run hotter without damage so thus the wire can also.

Bottom line - If you use the same wire on the 3800 injectors that was used on the 3800 injectors that is fine. Also since the injectors do not fire at the same time, in this case splicing the 3 of each bank or even 6 of both banks together into a same sized wire is OK. If you noticed on your donor harness this is what GM did.

Two things would worry me about fire with a swap harness - 1 Wire the negative battery cable only to the engine block and not to the vehicle frame. This is different than what GM did. If the battery cable would come loose at the block but still be grounded at the frame, the small wires in the harness would then become your 'battery cable'. They could not handle the load and would become red hot.

The second is to make 100% sure you have no leaking injectors. This did happen on one of my harnesses. It was quite clear it was caused by a leaking injector since all the fire was at that portion of the harness. A shorted wire would have scorched the harness along the run of the wire. This was not the case.

[This message has been edited by phonedawgz (edited 05-17-2015).]

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Adjustso3
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Report this Post05-17-2015 10:11 PM Click Here to See the Profile for Adjustso3Click Here to Email Adjustso3Send a Private Message to Adjustso3Edit/Delete MessageReply w/QuoteDirect Link to This Post
Sorry to hijack but I have a question about what Phonedawgz said about the grounding wire from the battery. You have me a little confused. Should the negative wire from the battery go to the engine or the frame ? Where is the best place to run the negative wire from the battery ? Thanks
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phonedawgz
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Report this Post05-18-2015 03:19 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Run the negative battery cable to the engine block only. Do not have the negative battery cable also pigtail to the frame. Also run multiple straps from the engine to the body. The engine to frame straps should be located on different bolts from the negative battery cable.

This advice applies to both rear AND FRONT mounted batteries.

[This message has been edited by phonedawgz (edited 05-18-2015).]

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Threedog
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Report this Post05-18-2015 09:11 AM Click Here to See the Profile for ThreedogClick Here to Email ThreedogSend a Private Message to ThreedogEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by phonedawgz:

Run the negative battery cable to the engine block only. Do not have the negative battery cable also pigtail to the frame. Also run multiple straps from the engine to the body. The engine to frame straps should be located on different bolts from the negative battery cable.

This advice applies to both rear AND FRONT mounted batteries.




What gauge wire for the straps?

I was thinking 4AWG from the batt to the bolt above the starter, along with the CPU/MAF grounds and c500 ground. Then the C203 and fuel pump relay grounds to the decklid bolt, along with one strap from the former coil pack location to the decklid bolt. Anything else you recommend?

Also are the coil packs grounded through the bolts they attach with?

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Threedog
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Report this Post05-19-2015 09:30 PM Click Here to See the Profile for ThreedogClick Here to Email ThreedogSend a Private Message to ThreedogEdit/Delete MessageReply w/QuoteDirect Link to This Post
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