AP700

Hi people!
I have a 502 MPI cool fuel engine. The shrader valve is broken, I dont know what happened to it at the PO.
The boat where the engine will run in has a permanent fuel pressure gauge on the dash so i would like to set a sender to the engine. I would like to get rid of the broken shrader and set the sender there but i have no clue what kind of thread it is. Senders are all 1/8 NPT i think. What do i need to get it installed to the port where the shrader sits normally?
Dealing with imperial system in europe is the real PITA.

Thank you guys!

SB

3 is the valve, 4 is the cap

AP700

Does anybody know the thread size of the valve? i want to delete ist and set a fuel press gauge sender there.

BadDog

You could retain the Sharder valve and adapt a fitting to the Sharder valve for your sender. I see that the part is NLA but there is one on Ebay, shipping could be a problem.
https://www.ebay.com/sch/i.html?_fro...05408&_sacat=0
https://public-mercurymarine.sysonli...eng&langDB=eng
A close look at the pic shows the thread sealant applied. This would typically be found with an NPT fitting. Is removing that going to introduce contamination into the fuel system, not sure what the flow path is and filtering, etc., and how you could flush it out.

BadDog

It could be 1/4 NPT, you can verify if you unscrew the fitting and verify that it is tapered, again be aware of the contamination concern. You can likely source NPT parts from a specialty shop or simply mail order. I am thinking a simple NPT plug and you can drill and tap to suit your sender.

Here is some info on NPT threads and measurements
https://www.machiningdoctor.com/thre...-npt/?tid=4002

and BSP
https://www.valvesonline.com.au/references/threads/

AP700

Thank you guys, I will unscrew the fitting and check what thread it could be and how to adapt my Sender to it. Maybe if it is 1/4 NPT and my sender is 1/8 NPT, i can get a adapter fitting and just screw this all together.

Thank you!

BadDog

That would be a best case scenario, I suspect if your sender is sourced locally it could be BSP and not NPT. It would be hard to tell so read the specs. The NPT plug would be easy to get ahold of as well as a BSP tap if it comes to that. All you need is a vice, drill bit and the tap.

snapmorgan

I think I remember them being 1/8" pipe thread, but it has been a long time since I had one out.

Griff

Its a standard NPT, but I don't remember the size. I was going to do the same thing as you want to do on 502mpi's since I have fuel psi gauges in my dash too. The problem is the fuel psi senders are too large to fit where the shrader valve is. You will need the exact right combo of fittings to get the sender to fit between the shrader valve and Tstat housing. I never ended up doing it.

AP700

Okay, I will try and tell you what i did!