Does anyone know what the little black box on the back side of the oil metering pump does? it has a 3 wire harness on it.

I just bought this 91 rx7 that someone replaced the small black box with a metal plunger out one side. It goes to the omp. it is plugged into the harness that the old one was plugged into.(the harness plug is on top near the tps). The problem is the old one (black box) is still connected to the oil metering pump. this new one has tape over the plunger to keep it down and is siting to one side under the hood.

What problem is this having on the car?
with tape over the plunger, (keeping it down all the time) the ECU is telling the omp to do What?

Also Should I be putting 2cycle oil in the gas and how much until I get this fixed?

any help is much appreciated.

Rich

 

You have a S5 RX-7. The series 5 RX-7 uses an electric oil metering pump instead of a mechanical pump like the S4.

It sounds to me like they tried to "wire open" the OMP so that it would just run all the time. Might be a band-aid for a failing OMP.

As for the 2-cycle in the gas... I forget what the ratios are, so you'll have to wait for someone else to tell you that

 

Premix = 100:1

The black box you are talking about is the omp position sensor... but I'm not sure what effect holding it down has... but its definately something that should be fixed ASAP. Run premix until you can get one. I have an OMP laying around you could buy if you want. PM me if interested.

 

that little box is the OMP positioning sensor I believe, and it seems like maybe that plunger dealie might be some rigged up way to stop the OMP while still sending signal to the ECU (basically deleting the pump without causing limp mode.) That is a possibility.

The 2 cycle to gas ratio for a non-working/removed/disabled OMP is about one ounce to a gallon, 100:1

 

lol, beat me to it

 

As others have said, it's the position sensor. The three wires are 5v, gnd, ecu signal.

 

Thanks guys ,big help.
Rich

 

Is there an easy way to fool the ECU so it won't go into limp mode? I'm new to the site so I haven't figured out how to navigate it properly so if there is old data on this I haven't figured out how to retrieve it. I would like to go to pre-mix but .....

 

Keeping the S5 OMP plugged in is the only option other than getting an RTek ECU upgrade or going standalone (both are expensive). What most people do is remove the S5 OMP from the front cover of the engine and leave it plugged in.. they just move it somewhere else. Then you just plug up the injector holes, removef the lines, etc. That way the ECU sees the signal from the OMP, but you can still run premix.

Personally the best option is to fix the S5 OMP and get it working properly. Once again, I have an S5 OMP I'll sell ya.

 

I thought that might be the case. How much?

 

I'd like to offer it to the OP of this thread first if thats okay.. if he doesn't want it, its yours..
60 bucks shipped?

 

let me know. rconnolly2@woh.rr.com
Bob

 

I am interested in the omp from you. I am in the process of making sure mine is bad first. I will let you know Monday .Thanks for offering it to me first.
Rich