I'm working on a swap project ('88 TPI into 1986 Chev truck) and I've run into a problem.

I used the SDPC Vortec TPI base, and I can't use the oil pressure tap next to the distributor. Only two spots left, and the one at the front of the motor isn't really useful with the other stuff I have.

I'd like to use a later ('91?) combination fuel pump switch/gauge sender, but I'm not sure if the sender output is different than my truck gauge. Not enough room with headers and the fuel pump switch and large bell sending unit above the oil filter.

Truck gauge is a 60PSI unit, and if the '91 Camaro is the same PSI, I wouldn't be surprised if it were the same PSI/Ohm rating.

I checked, and the '91 Camaro uses a different switch/sender than a 1991 truck, but I can't figure out what is different.

Any help would be much appreciated!

 

im not sure this would even work since ive never tried it..... but could you use compressed air on the gauge sender and see what it gives, then compare that to what the stock one does?

 

I'm sure I could, the problem is, I don't have a switch/sender combo yet, and I'd hate to buy one and find it doesn't work.

The trucks used a 60PSI unit, but I don't understand why, if the '91 Camaro gauges are also 60PSI, the car and truck 60PSI senders don't cross. If the Camaro senders were 80PSI (for example) however, the difference would be obvious.

 

With exception to the temp gauge, most every GM oil and gas gauge through all years works using 0-90ohm resistance for their min-max readings.

 

Gauge/sending unit "swappability"?
Still, question lingers, if the ratings are all the same (0-90ohm for 60PSI units, the 80PSI diesel truck units had a different rating) why are there at least 3 different setups?

('91 TBI V8 truck, '91 TPI V8 Camaro, and V6's all use different part #'s to do the same thing as far as I can tell, although one is TBI others are TPI or the like)

Not *trying* to be **** here, just trying to figure out what the differences are, and whether or not I could just use a 1991 truck switch/sender with the '88 Camaro harness and '86 truck gauge. (obviously I have to cut and splice wires, but that is inevitable anyways) Believe the answer is yes, but with there being at least 3 different part numbers, some doubt still exists for me.

 

Best thing I could tell you is go to your parts store and ask to look at the different units. If they are different physically, that would be the reason for the different numbers.
I used the old 'bell' style sender from my 'bird (since I put all new everything on it) on my ex-suburban and it worked fine and the units looked extremely similar aside from a small size variance.
If I had the brains to explain how they are calibrated (60-80 psi units) I would but, I'm not that smart
I just know by specs (and very mild exp) what they do. The fuel sender from my bud's 72 truck works (0-90ohm) with the 86 camaro cluster I put in it.
Stick a 45 ohm resistor inlne to ground on the sender wire and the gauge should read 30psi. The camaro unit works 0-90 so if 45ohm make the truck gauge show 30, you should be alright.
That's how I checked my gauge anyways since running a high vol oil pump and the gauge is pegged 100% of the time I wanted to be shure the gauge wasn't messed up when I popped off the needle and painted the backside.
Just my exp.. take it as you wish. It may not be 100% accurate or the right way.

 

I appreciate the comments.

I guess you are right, I can compare the two if the store has them in stock. I looked at some pictures at an online car parts site, and they look slightly different externally, but not enough to warrant a different part # based on looks. Of ocurse, you can't always believe online pictures, so who knows.

However, if the threads are different or the connector is different, that is likely the reason for the difference.

Of course, on the truck bulletin board, they mentioned that '87 trucks used a similar 3 wire sender/switch, PLUS the big bell shaped sender! Then in '91, they were only using the combination piece.

More to discover I guess!