I need a little help wireing the 88 Fiero oil sending unit, Engine is a 3800 SC II. I found a pic,showing the the 88 Oil sending unit wireing (I cant seem to get PIP working right now).The pic shows the wireing as fallows (88 oil sender). Orange/Black 12 V Switch. Tan wire from oil pressure gauge. Tan--White wire, to fuel pump. I cant seem to locate any wireing, for the oil sending unit in the engine compartment. I have the 3 wire plug,but Im not sure what to patch into,maybe the fuel pump relay (???).Any help is appriciated....Thanks.

[This message has been edited by James Bond 007 (edited 05-29-2013).]

You don't need to run the fuel pump power circuit thru the oil pressure sending unit. GM used to do it that way because they thought their fuel pump relays were unreliable (and in some cases, they were).

In all the 3800 swaps I do, I replace the stock Fiero fuel pump relay with a newer GM unit that is weather-sealed (which are much more reliable than the OE Fiero fuel pump relay). I delete the fuel pump backup power wiring thru the oil pressure sending unit/switch and only wire the sending unit up to the gauge. To do it this way, all you need to do is run the tan wire from the center pin on your 3-pin oil pressure sending unit to pin E of the Fiero's C203 connector. That's it.

-ryan

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[This message has been edited by Darth Fiero (edited 05-29-2013).]

Thanks for the Tips Ryan.What are you useing for the Newer fuel pump relay (what Vehicle)? As for the oil sending unit,you say " all you need to do is run the tan wire from the center pin on your 3-pin oil pressure sending unit to pin E of the Fiero's C203 connector." What, no ground wire? Only a one wire hookup?
found this wireing link for anyone who interested.
http://www.dohcfiero.com/Factory%20ECU.htm

N/M

[This message has been edited by TK (edited 05-29-2013).]

Bump....

quote Originally posted by James Bond 007: Thanks for the Tips Ryan.What are you useing for the Newer fuel pump relay (what Vehicle)? As for the oil sending unit,you say " all you need to do is run the tan wire from the center pin on your 3-pin oil pressure sending unit to pin E of the Fiero's C203 connector." What, no ground wire? Only a one wire hookup?

Yes, 1 wire hookup. The Fiero 3-wire oil pressure sending unit's gauge output grounds thru the threads on the sending unit itself - so make sure you use a liquid or paste thread sealer and NOT teflon tape on the threads of the sending unit.

Relays - Late 80's thru late 90's GM cars and trucks used weather pak connector relays. You will NOT find these relays inside of under-hood fuse and relay centers (there are typically NOT weather sealed). The weather sealed ones will be mounted individually to a bracket on their own or with a bank of relays exposed in the engine compartment somewhere. Most early to mid 90's GM FWD cars that had ABS had their own stand-alone weather sealed relays that had some nice fat wires going to them (usually grey in color and say ABS right on them).

You'll know the relay is the weather sealed (weather-pak connector) type if it has silicone seals on the connector for it and NOT packed with that sticky grease like GM put on the stock Fiero relays.

[This message has been edited by Darth Fiero (edited 05-30-2013).]

I run the wires to the back up fuel pump switch on the oil pressure sender. If the relay were to fail, or the driver for the relay circuit, you would be damn happy to have the back up.

The '88 Fiero oil pressure sender grounds the oil pressure gauge internally.

I however wire as follows

A - Tan - Oil Pressure Gauge sender

B - Black - Ground (for sender)

C - Orange/Black - +12v from fuse box

D - Tan/White - to Fuel pump

This allows you to use either the 88 Fiero sender or the 98 Bonneville sender. The Fiero is a 0 - 90 ohm (0 - 80 PSI) sender along with the back up fuel pump switch. The Bonneville sender is also 0 - 90 ohm, but the pressure range is 0 - 120 PSI, and it has the back up fuel pump switch. Many 3800s run more than 80 PSI of oil pressure. If you use the Bonneville sender your oil pressure gauge will not sit pegged. Note the final number on the gauge should be relabled to 120. Also note - The oil pressure gauge on the Bonneville reads 0 - 40 - 120!!

88 Fiero sender - Delco 1808A or 12555492
98 Bonneville sender - Delco 10206847 or STANDARD MOTOR PRODUCTS Part # PS246