I was thinking of going with Patman's DIY 2 Stroke Oil Pump, but before that, I would like to get an idea of how often the OMP fails!

If the reason people are premixing is because the pump usually fails, then having a separate reservoir injecting nice, premium 2 stroke isn't going to do much to save a motor.

Thanks.

 

it depends on the series man, the designs have changed over the years, and have only been electronically controlled since series 5. Series 5 seems to fail the most at least in terms of going into limp mode due to a stepper motor failure.

So what kind of failure are you talking about? physical failure of pumping capability (while electrically it's still fine), a blockage or leak in the oil lines, an oil injector failure, or an electrical problem causing limp mode? A lot of FD owners have ditched the stock ECU and the Power FC doesn't even have limp mode to my knowledge, so people aren't going to be as likely to report a confirmed failure.

 

i have a good pump if anyone needs them.. Think i have two actually. dont need it so any reasonable offer accepted.

 

i have been playing with Rx7's since 1993, and after owning 20ish, and working on tons more, i have only seen 2 non electrical metering pumps stop pumping oil.

99.9% of the time they work fine, and leak externally.

.1% of the time it stops pumping.

car 1, is an 82

car 2 is a 79. this one does not pump if you put thin oil in it, if you use a thick oil like 20-50 it works fine.

considering the failure rate on the metering pump (except for external oil leakage) is lower than just about any other part of the car, i dont think there is anything to worry about.

or if you're worried, buy a NEW pump, we used to stock it at the dealership (they leak externally...)

 

the s5's fail all the time. the stepper motor that actually controls how much oil is delievered will have an electrical short that will fry the ECU.

 

Thanks for the responses. I have an FD, so I suppose that is an electric pump. I am also running the PowerFC, so it is potentially disastrous if the pump should ever fail since there is no limp mode!

And to clarify, I did not mean blockages in the lines. I meant the pump physically stops pumping.

What is an easy way to determine the condition of the OMP? Is there some electrical resistance that can be measured somewhere, or something simple like that?

 

When I got my '80 (89,000mi), I drove it for 2,000 miles before I noticed that it was not using any oil. Checked the OMP output: zero.

No clue how long the previous owner drove it like that.

I started premixing, drove it until 119k, pulled it out to put a streetport in the car. Several years later, I took the engine apart to turn it into a P-port - looked fine inside. A bit of chrome flaking, but a lot better than most 3mm seal engines I have pulled apart.

The OMP in my '85 quit not long after I got the car. I premixed every now and then, when I felt bad.

The one in my '84 was all borked from a goofed-up Holley carb installation. When I put the car on the road it was with a Nikki carb setup, and the OMP was mainly there for looks. Didn't do much of anything except leak everywhere.

When I have an engine apart, I usually just remove it and block it off, eliminating a source of an oil leak, as well as the associated hoses and linkage. Premixing is no big deal, really.

 

if you have the power fc, it gives you the position sensor voltage in one of the screens. it'll be highlit if its out of range.

 

Thank you for your replies.

I've been weighing the pros and cons of premixing vs 2 stroke oil injection, and I think injection is good as long as the pump is reliable and easily checked for reliability (using PFC, described above). Of course, now that my engine's apart, it is easy to run a flow test.

I'm pumped for some 2 stroke oil injection!

 

actually in like a low speed parking lot sitch, you can hear it if theres no metering pump oil, it sounds scratchy.

 

What did you use to check it?

 

The service manual details removing a OMP hose, running the engine at a certain RPM, with the OMP rod at "max", and measuring flow. Or something like that.

Carbureted cars don't have banjo fittings, so you can just slide the lines off of the nipples on the carb. Or, you can just remove the air cleaner lid and look down the venturies with the engine running, and see how much oil is drooling out of the business end of the OMP nipples. Or not, in my case.

Additionally, the lines are kinda translucent, they will be white to yellow if they are empty, and dark with oil if the OMP is actually doing something.

 

^Got it. Thanks man!

 

Has anyone seen there pump open up and start dumping oil in the motor like crazy? I have a buddy that his FD smokes like a bastard? It has done that with his stock motor and his brand new motor as well so we know its know the engine itself.

 

i have pulled down many engines,, and i am yet to see a failed OMP
-- apart from leaks at the end caps and broken delivery lines,, and the lever shaft O ring failing
the only time i have seen them NOT work,
, is when some gumby has siliconed over the supply port in the timing cover gasket

however,, of the EOMP,, i have helped develop a stand alone controller
,, and it involved handling a fitting a few along the way
-- NONE had displayed a fault in the armature winding
,, though i am sure it does occur,, and there is an FSM test expressly for it

but TWO ,, ( representing a significant fail ratio ) had faults in the feedback sender for the OMP motor
-- one off scale,, the other dead ranged in the middle
-- i believe one of these was responsible for the original ECU introducing a timed out limp
and the other caused the EOMP to hunt in some conditions
( which may be what contributes to the transistor dying , along with a total pole out of one of the step windings )

i believe that many EOMP faults are related to oil and dirt effecting the feedback sender,, rather than the pump itself being faulty

and BTW,, a failed drive circuit,, or and unplugged EOMP still pumps oil
-- it will stay at the last determined position where it failed
-- and this only effects the rate,, and does not stop oil flow all together