fuel pump safety switch wiring
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Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0).
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
The full forum rules are here: Forum Rules, be sure to read them all regularly.
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tunnel ram efi
- MegaSquirt Newbie
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- Joined: Thu Sep 25, 2008 5:29 pm
fuel pump safety switch wiring
I am using MSII with the relay board and cannot find a wiring diagram for the fuel pump relay and a oil pressure safety switch. I am using a 3 prong switch from a early GM, not the specified Holley switch. Is this not just a limp home feature if the relay fails? Thanks Rich
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Matt Cramer
- Super Squirter
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- Joined: Sat Jul 03, 2004 11:35 am
Re: fuel pump safety switch wiring
Usually you would use the MS to cut power if RPM drops to zero instead of an oil pressure safety switch.
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tunnel ram efi
- MegaSquirt Newbie
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Re: fuel pump safety switch wiring
Why do GM tpi motors use this set up and what happens if the fuel pump relay quits? Rich
Re: fuel pump safety switch wiring
"Why do GM tpi motors use this set up and what happens if the fuel pump relay quits?"
First off, I don't know how GM used the switch. If the fuel pump relay quits, the fuel pump quits, and your engine quits. Replace the relay. There is no 'double safety' or 'limp' mode for the fuel pump.
With that said, if you wire the oil pressure switch inline with the impact switch, Your car will not start until there is oil pressure, and in the event of an oil system failure where you lose oil pressure, it will also kill the pump, possibly limiting damage to the engine.
First off, I don't know how GM used the switch. If the fuel pump relay quits, the fuel pump quits, and your engine quits. Replace the relay. There is no 'double safety' or 'limp' mode for the fuel pump.
With that said, if you wire the oil pressure switch inline with the impact switch, Your car will not start until there is oil pressure, and in the event of an oil system failure where you lose oil pressure, it will also kill the pump, possibly limiting damage to the engine.
Daryl
'66 Datsun Sport Convertible, R series 1800cc Pushrod
MS II, Ver. 3.0, LS2 coils-waste spark, Homebuilt Intake. LC-1 WB
'66 Datsun Sport Convertible, R series 1800cc Pushrod
MS II, Ver. 3.0, LS2 coils-waste spark, Homebuilt Intake. LC-1 WB
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tunnel ram efi
- MegaSquirt Newbie
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- Joined: Thu Sep 25, 2008 5:29 pm
Re: fuel pump safety switch wiring
I am pretty sure that the oil pressure switch by passes the fuel pump relay to provide voltage to the pump in case of relay failure. I found out that GM no longer installs this feature, so nor will I. I was just trying to follow Megasquirts wiring instructions and get all the necessary wires in my harness before shrinking the tubing. I appreciate everyones help. I am sure I will need much more. Thanks Rich