G63B | oil sensor and electric fuel pump

[jdmckay]

Hello,

I'm just finishing up converting my '89 MM to an AirTex electric fuel pump & Redline Weber after motor rebuild.

I want to wire a cutoff to fuel pump if oil pressure drops. I want a 3 prong oil pressure sensor: terminals P,S & I for this purpose, but have been unable to find one. I ordered one from RockAuto, but thread size did not match. According to technician atAirTex's sensor site (http://www.airtexve.com/custom_searches/ds_oil.php?showall=yes), this sensor's thread is: 1/8-28 ISO Tapered Thread. Can anyone confirm this?

AirTex lists a ton of oil sensors, but none with P,S & I terminals with this thread size. I have emails out (no response yet) to several Carter vendors, asking if they have one.

If anyone has a part. # and/or supplier, greatly appreciated.

[noahwins]

Maybe this will help?

http://www.wellsve.com/parts/

[jdmckay]

> Maybe this will help?

Thanks... same as AirTech site: no "safety" (3 prong) switches for this thread size. I have confirmed stock part's thread size is: 1/8-28 ISO Tapered.

I did find this (http://www.autozone.com/fuel-system/oil-pressure-safety-switch/airtex-products-oil-pressure-safety-switch/185103_0_0/) AirTex switch on AutoZone. Thread size is not listed, but their site says it fits my G63B (crossing fingers). I called nearest AutoZone, there's one in stock on other side of town and they'll have it here early tomorrow. Can check thread size then.

[jdmckay]

Switch I linked to from AUTOZONE (http://www.autozone.com/fuel-system/oil-pressure-safety-switch/airtex-products-oil-pressure-safety-switch/185103_0_0/) in last post is incorrect thread. I'm surprised nobody has come up with solution, given the many discussions here on WEBER/electric fuel pump conversion.

At this point, I'm inclined to plug my existing sensor hole and tap/thread to match one of the many safety switch thread sizes w/PSI (low) ratings appropriate for this motor. I've put a lot of time/$$ into rebuilding this old truck for long term reliable use, and really don't want to 1/2 ass anything this close to reaching that goal.

[pennyman1]

There is a thread on here where I give the part number for a 3 prong sensor like you are looking for, it is a wells ps128. You have to get an adaptor fitting to adapt the switch to the metric port on the block. I got an adaptor kit with various adaptor fitting in it to match up the port on the block to the switch. Best way is to go to a real auto parts store like napa that has fittings in a drawer with the oil light switch from the block and the switch and get an adaptor that matches up. I have run this switch this way on Geronimo for 31 years, and the only problem I ever had was the switch failing, not the fitting leaking.

[jdmckay]

Thanks PennyMan... read/searched everything here I could find on electric fuel pump/weber conversion but did not see that.

I went to NAPA and several Performance specialty stores here (Albuquerque), could not find adaptor. You said the block's thread was metric (right?): from all I determined, it is a little used thread anywhere: 1/8-28 ISO Tapered.

Anyway, I pulled the mounting plate for fuel pressure switch/oil filter off the block yesterday, took it to a machine shop and had it re-threaded for 1/4 NPT thread... whole bunch of switches from Wells/AirTex/BorgWarner with that thread. Bought a BorgWarner @ O'Reilley's. Machining was just $20.

One thing I am curious about (haven't looked at my Chilton's manual for this yet): my engine rebuilder mounted that adaptor plate w/out a gasket (he screwed a bunch of things up). Several cutouts on the mounting face w/block had gasket residue, he just used some type of "form a gasket". Thinking best to put a gasket in there, I have plenty of gasket material. If anyone's sure about this I'd appreciate knowing.

Thanks.

[pennyman1]

My adaptor plate for the pump blockoff on Geronimo is sealed with silicone form a gasket - 30+ years and counting - no leaks.

[BradMph]

The only reason gaskets are used anyway is to compensate for uneven surfaces. If manufactures got surfaces absolutely perfect, the gasket making companies would go out of business.

I made my own gasket and used a very thin layer of gasket making permatex RTV, temp safe. I'll be dead in less then 30 years, so Pennyman's record will still stand, lol.

[jdmckay]

Thanks guys.