Problem Solved:: Gauge issues

[19kflo80]

The gauge pegs out to the far right wether connected or disconnected. I haven't tried grounding the plug.  I have tried two other factory gauges that i have at my disposal and both do the exact same thing.  I have tried testing the SU but i don't know what i should be looking for. Ive looked at the trouble shooting gauges thread and its just a bit over my head.

[LTZ C20]

I'm not sure like irish said about mixing different year senders and gauges. I asked our shop foreman what sender I could use in place of the stock type, his suggestion was the 90s style I'm using now, he never said anything about it may not working, don't think it should be an issue as oil pressure should be bout the same for most 350s of any year I'm guessing. My oil pressure gauge seems to work as normal with the newer type sender. The gauges has always been a bit jumpy and sticky, being the original I'm sure it wouldn't hurt to get a new one. But when the pressure drops I know about it so not to worried at the time.

My guess would be check the tech section, look under your appropriate year for the sender and find the section about diagnosing low oil pressure or no oil pressure, something has to lead to the technique to checking the sender itself.

[Dr_Snooz]

The gauge pegs out to the far right wether connected or disconnected. I haven't tried grounding the plug.  I have tried two other factory gauges that i have at my disposal and both do the exact same thing.  I have tried testing the SU but i don't know what i should be looking for. Ive looked at the trouble shooting gauges thread and its just a bit over my head.

It's a single wire connection, so most likely the circuit grounds through the sending unit to the head. If the resistance across the sender is the same with the engine off as it is with the engine running, the sender is bad.

Again, I don't have the wiring diagrams. I'm inferring based on the design of the sender. It's a good inference, but someone who knows is welcome to chime in.

[19kflo80]

Bought a new OPSU and compared resistance measurements from connector on OPSU to the base of OPSU.  The results, OLD: 50 mohm; NEW: 0.15 ohm.  I installed the new unit and my gauge no longer pegs out.  However, i started the engine to check operation and the gauge started moving like the seconds hand on a clock all the way up to about 50psi and stopped. I changed the gauge out with a different one and same thing. Now........ The darn thing wont even stay running. I know the two aren't related but i don't know whats going on now.   

[Dr_Snooz]

50 sounds like a normal reading. We might need more details for the other issue.

[19kflo80]

At this point i dont have any testing details other than a visual check, at the time i was too frustrated to do anything else.  But, heres what i got:  motor has been rebuilt, new plugs, wires, distributor, o2, and new fuel pump and sending unit.  The timing has been set using the proper method. The truck ran perfectly normal up until last night.  I replaced the OPSU, cranked and checked gauge for proper operation, the engine ran for a minute or so and then started to stumble and die out. The fuel level was low so I thought i may be running out, added 5 gal and tried restarting. Engine backfired thru the TB, tried again and started but running like scat and stumbling for about 10 seconds and dies. You can rev engine, but it skips and stumbles and eventually chokes itself out.  The more i experimented the worse it got. By the end of the night, engine would not start at all.

[NCali]

I just found an open trace on the circuit panel on the back of the dash . It is not real easy to see , I found it with a meter and it fixed all of my gauge trouble

[LTZ C20]

Good. What about the engine trouble now?

[Irish_Alley]

might want to start a new post about the engine

[roundhouse]

Depending on how you did the conversion
Some TBI setups use a oil pressure switch to activate the fuel pump


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[Irish_Alley]

if you give the little red wire on the fuel pump relay 12v it will bypass everything and should power the pump

[NCali]

There is another oil pressure switch up by the distributor. You may have pulled the wires off of that switch  inadvertently

[19kflo80]

The fuel pump is coming on, i think its just too much fuel for whatever reason. Thanks everyone for your responses, but i will be starting a new thread for im sure that anyone else having the same problem will not look under "gauge issues" for help with a poorly running engine.  Thanks again!