'89-'91 OMP Question
 

As some know, original owner '89 TII and finally got bitten with the OMP failure. First time the car has been out since last August, and on the way home while on 295 tried to accelerate to put the cc on, but the car stumbled, so got off at next exit ramp, did a visual and drove home gingerly. Once home checked the CEL, 27 and a couple others, O2 and boost solenoid.

On to my question. I have a couple used OMP in the garage, and will purchased a new "O" ring (N350-14-604) as they call it, but how many crush washers are needed at the banjo fittings on the pump, and second, is this the correct part number:

9956-20-800-Oil Metering Line Crush Washer
ID .325
OD .512
Thickness .054

TIA

Four washers are required, one per bolt. You might want to check your electrical connections at the OMP before suspecting the pump itself. Sometimes these connections become corroded causing the resistance to increase and the pump doesn't get the required voltage.

Thanks, just wasn't sure as with crush washers thought that there would be one over, one under each banjo bolt, but 4 it is.
Did look at the FSM and saw some of the voltage/resistance tests that I will try when I decide to do the job, but anymore can't stand working on cars, let alone this one as it isn't driven very often. Actually if Dave was closer, the car would go there. Yup, lazy in my old age!

there is a single copper gasket on the OMP side of the lines, N350-14-602.

Well, you might be right on that. The parts microfiche showed one crush washer with the bolt, but listed number of bolts as four. The parts microfiche never listed the total number of crush washers. So, it becomes sort of a guessing game. Since they're only $2-3 each, I would recommend buying 8 of them just in case. You could always return the unused washers.

For the plain copper crush washers on each of the banjo bolts, yes you'll need 2 washers per - one on each banjo surface, so 8 total at the OMP - BTW, these are much cheaper to get from McMaster-Carr, Fastenal or any other decent hardware supplier than from Mazda; $15 for a 50x bag vs. ~$2 each. Then there's that one oddball copper gasket (with the 4 holes in it) that goes between the OMP & the engine's front cover - no choice but Mazda for that one.

Hot Dog and Pete 89T2, thanks for the replies. I did look at the used unit in the garage again, and the 5 hole crush washer looks to be on the OMP side where the banjo bolt would be sandwiched between the 5 hole washer and an individual crush washer, with the "O" ring on the engine side.

Thanks for the Fastenal tip as there is one not very far from my location. I did mic the OD and it was .531, but will take other measurements tomorrow and see what they have, then all I'll need to do is get up enough energy to do the job. Certainly not like years ago when I'd pull or rebuild an engine at any time.

Once again, thanks for the replies and as usual it's greatly appreciated.