Fuel Pump Wiring GM 350 TPI

For discussing how to choose sensors and create a wiring harness for all Bowling and Grippo versions of the MegaSquirt® EFI controller.
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Mik
MegaSquirt Newbie
Posts: 2
Joined: Tue Mar 08, 2005 1:29 am

Fuel Pump Wiring GM 350 TPI

Post by Mik »

I'm (still :) ) going to swap old original ECM to MS+MS-II daughter card.

I would like to use my original Fuel Pump relay, but I need help for wiring it to MS db-37 connector.
I draw my current wiring here: http://metso.sigmatic.fi/~atjw/tpi/fuel ... elpump.htm

Would it be right if:
- I connect FP Relay term. 'C' to Ignition switch (Hot in Run, Bulb test and Start)
and
- FP Relay term. 'B' to MS db-37 connector pin # 37

... or how ?

And how about fuel pump / oil pressure swicth sender?
What might be its funktion? I don't even know where it is im car - I read only my cars scheme ) ? :?

So, how would I wire it :?:

Mik
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89rssq
MegaSquirt Newbie
Posts: 1
Joined: Sat Oct 23, 2004 8:52 am
Location: MA & CT, USA

Post by 89rssq »

the oil switch/fp cutoff cuts off the fuel pump if the engine for some reason goes below 5psi of oil pressure.

i'm going to be running this in my camaro, and i think i'm just gonna remove the stock underhood relay. but if you're running a thirdgen fbody, check out www.thirdgen.org for info on the wiring. should be able to find everything you need there.


Dan
89 Chevy Camaro RS
400 sbc, edelbrock performer, hei, hedman headers, hooker catback, th350, holley carb

soon to be a MS setup with tbi (or 2) FI
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WopOnTour
MegaSquirt Newbie
Posts: 3
Joined: Fri Aug 06, 2004 10:53 am
Location: Nowhere man

Post by WopOnTour »

89rssq wrote:the oil switch/fp cutoff cuts off the fuel pump if the engine for some reason goes below 5psi of oil pressure.
Dan
Negative Dan
On all older GMs equipped as such, the oil pressure switch closed above 5 psi as a backup for the main fuel pump relay / control circuit only . As long as you are cranking or running (ie ign ref coming from ignition) the GM ECM will send B+ out to the FP relay and the pump will run (whether you have ANY oil pressure or NOT).
Most GMs dont even use this switch anymore.

Mik-
To answer your original question. Since the original GM ECM supplied B+ to a grounded relay, and the MS applies a ground for the "sourced" Fuel Pump relay- you will need to do a "switcheroo" on the FP relay control circuit wiring is all. (ie apply a source of IGN+ from MS MAIN RELAY to terminal #86 of the FP relay and then connect pin 37 of the MS to terminal #85.

HTH
WopOnTour
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Mik
MegaSquirt Newbie
Posts: 2
Joined: Tue Mar 08, 2005 1:29 am

Post by Mik »

Thanks both of you!

Dan - yes I have thirdgen fbody. I found more information about my 'oil switch/fp cutoff' from thirdgen website. It seems to be only backup for the main fuel pump relay (as WopOnTour told too) - so, I don't need it in MegaSquirt. If I need 'safety system', I'll have to install some safety switch (e.g. Holley - 12-810).

It looks like that it would be better if I don't use my stock underhood fp-relay at all and wiring my fuel pump and relay just like in http://www.megasquirt.info/manual/extwir.gif picture. - that is just what WopOnTour told ... I think so.
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