Hey everyone! I have a question that was brought up before on this thread, but i am not sure how correct the info was. Well i have just swapped in a TPI motor intp my 1995 YJ and need to get my oil pressure gauge to read right. I have a Painless harness and they said that i had to use the Chevy switch. I know have it wired to my Jeep gauge and it's just pegged out when the Jeep is running.

Someone stated that he used 1 1/8 VDO gauges for the smaller ones on thee dash. They look bigger than that to me. Granted i have not torn the dash apart to measure them.

Does anyone have any input that would help me out?

Thanks.


"May your Jeep one day be finished" HA!

That might've been me. I used 1-1/8" small and 3-1/8 inch big gauges in the existing dash when I put in the Ramjet. However, I re-did all the gauges at the same time and replaced the entire cluster with a panel of plexiglass (painted the back side black, left the shiny side out) and installed the separate gauges in that.

Because all the center gauges are in one cluster, I don't know if you could just replace one very easily. When you get the dash apart, you'll see what I mean. You might be able to remove the guts from the new gauge and transplant them into the cluster, but it'd take some careful work to get it to come out looking right...

Good luck,
Jake

There's a picture of my gauges on this thread:

http://www.pirate4x4.com/forum/showthread.php?threadid=44334

Hey Jake, thanks for the help. I guess i will have to replace all the gauges. Where did you get them ?

Summit. The 5-pack was on sale for $230 or so when I bought them. Then I purchased the tach and ammeter as singles for another $85 or so...

Damn. At the time I bought 'em, I'd become so accustomed to pissing away scads of money on all the other aspects of the engine swap, it seemed like a drop in the bucket. Seems like a lotta money now though... :eek:

Jake

I know what you mean, i have to hide my receipts from my wife. I just finished a $12K swap.
Thanks again, i will try Summit. Hope there price has come down

Why not just find a way to adapt the YJ sender to the 350 block? With my 302, it was just a matter of one or two off-the-shelf brass fittings, and that's gotta be cheaper than a new guage.

With the YJ sender, your guage will read accurately, and the operating pressure of a 350 has gotta be in the same ballpark as the factory engine was...

Chris (you can do the same trick with the temp. sender)

Hey Chris, the jeep runs down the road at about 190 degrees. That is with the Chevy temp switch and Jeep gauge. I have 3 friends that have gone with the 302 and did what you did, and it works fine. But I went with the Chevy TPI because no one in my area has. I also went with a Painless harness and they said that with their harness i have to use the Chevy oil switch (for ECU reasons). So that leaves me with swapping gauges.

Thanks for the input though.

I don't understand the painless kit requiring the Chevy oil pressure sensor unless it has a low oil pressure shut down.

If it is required there is no reason you couldn' plumb in 2 oil pressure sending units. Seems like a lot more work to swap out all the gauges.

I'm running a '95 LT1 in an '89 YJ using the stock Jeep sending unit and the stock Jeep gauge. I also used a Howell harness that does not pick up oil pressure. I didn't even change the fitting on the engine. Both the Chevy and the Jeep had the same thread. I also used the stock Jeep coolant temp sensor.

My 88 TBI relies on oil pressure to turn the fuel pump on/off. On startup, there is a primer circuit that turns on the fuel pump for 3-5 secs (don't quote me), then when you start the engine, if oil pressure is adequate, the ECM turns on the fuel pump for non-stop operation. If oil pressure drops (don't know what value its looking for), the ECM shuts off the fuel pump. Thus the engine won't run and cause damage because of low oil pressure. Pretty slick idea from GM if you ask me.

Chris

The oil pressure switch (used by ECM for fuel pump shutoff) and the gauge sender are two seperate things.

by chance do you know where the oil pressure switch and fuel pump relay are located? i'm trying to find them so I can remove and reinstall in my CJ. Are they under the dash or in the engine compartment.

I am most familiar with TBIs, but I believe the TPIs are similar, if not the same.

The oil pressure switch is on the top rear rail of the block (just below the rear of the intake) towards the driver's side. The fuel pump relay (in GM trucks ) is mounted on the passenger side firewall, up high....it's usually next to two fuses.

Charly

According to the schematics, there are three wires going to the "fuel pump oil pressure switch" - Tan, Orange & Grey. Tan being the wire that feeds the gauge cluster, Orange being +12v all times, and Grey being the wire that goes to the fuel pump/sending unit.

Can you confirm?

Chris

Hey Charyl, my oil pressure switch is exactly as tys discribed above. The single tan wire goes to the gauge. The only other sensors or what not on the block are the knock and temp.

What do you think of It1yj's idea of putting the facrory Jeep sending unit on the block also. My Chevy oil switch is mounted above the oil filter. I guess the only other place for the Jeep unit would be below the intake manifold. And with the motor already in the Jeep I am not sure if it is accessible enough to install it there. So I might have no other choice than to replace the gauges.

Like I said, my experience is with the TBIs. But I'd say the idea about putting the jeep sender in sounds plausible. Is there room at the oil pressure switch to put a tee and add the jeep sender?

Originally posted by 1tonyj
...My Chevy oil switch is mounted above the oil filter...

1tonyj-

I have something hanging off my block in this location as well. I don't have the harness on the engine right now, so I don't know what color wires go to it, but my guess is that it's the oil switch. What year is your engine/harness from? Mine is out of an 88 Chevy G30 Van (2wd). It had a TH400 attached as well, but I sold that in favor of the SM465/NP205 package I picked up in PA.

Thanks,
Chris

Um.....an 88 van will have a TBI engine, and that 'thing' above the filter is the oil pressure gauge sender. My engine is from an 89 G20 van, BTW.

Tys,

Charly is right, that is your oil pressure switch. Do you have the factory service manual for the donor van? It is an invaluable reference. I went with a TPI system from a 87 camaro, a SM465, and a Dana 300. I also went with an after market Painless Wiring harness. It took all the guess work out of the wiring. It was all plug and go. Dummy proof.

Chad

No, that wil be the pressure gauge sender, the oil pressure switch on my TBI was behind the intake,on the rail.

1tonyj- No I don't have the FSM, just the Haynes manual. It is good, but not like the FSM's. Matter of fact, I was wondering if someone watching this thread could scan in the page that shows the 2 connectors going into the ECM, which identifies each wire to a connector position. The Haynes identifies each wire, and color, but I don't know what position and in what connector they goto. It would be GREATLY appreciated!

Charly- So let me get this straight, there is an oil pressure sender (for gauges?) and an oil pressure switch (for fuel pump)? Let me look through my schematic here...:smokin:

hrm...my schematics show a block and call it "oil pressure switch & sender". It feeds the oil pressure gauge in the cluster, but does not show where it originates (well, it only shows on a previous page as coming from the "fuel pump oil pressure switch. I guess you could argue that the "&" means two devices, but it is not detailed enough to be explicit. I am now away from home and cannot look at my setup to provide more details. I am only working from memory, and from the Haynes schematics I photocopied and brought with me.

Again, any more info/pics/scans are appreciated.

Thanks guys!

Chris

I think I just figured out and understand the sender/switch issue.

The sender is on the block and provides signal to two places, the guages and the switch (probably a relay right?). Whatever the oil pressure is, the sender reflects it by signal strength or pulse(s) or something, and it is converted into the analog gauge in my cluster. Second, if the pressure is adequate, the relay is energized by the signal to allow the fuel pump to run. Can you confirm it is a relay?

BTW, the nice thing for me is that I own a 94 Z71 w/350TBI. Unfortunately it is not with me to look at. :(

Still need the FSM copy of the ECM connector for my swap.

Thanks.

Chris