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-   -   502 Mag plug reading (https://www.offshoreonly.com/forums/general-q/375195-502-mag-plug-reading.html)

getrdunn 03-27-2022 09:51 AM

I wonder how the plug wire resistance is on the boogered up ones. Would be something to check also that doesn’t take much time.

DrFeelgood 03-27-2022 10:12 AM

Plenums and fuel rails off, injectors out. They look pretty crusty. Several visibly distorted or damaged o-rings, and many of the spacers (?) at the top of the injectors are badly distorted or compressed. This pic is after a brief soak / rinse in gasoline. They were significantly worse beforehand.

Think it's worth sending these out or should I plan on finding new?


https://cimg6.ibsrv.net/gimg/www.off...1d7196727a.jpg
https://cimg0.ibsrv.net/gimg/www.off...584b099f68.jpg


F-2 Speedy 03-27-2022 10:23 AM

Send them to Smitty ( Articfriends ) on here he's rebuilt and flowed several sets for me and others.

getrdunn 03-27-2022 10:32 AM


Originally Posted by F-2 Speedy (Post 4826638)
Send them to Smitty ( Articfriends ) on here he's rebuilt and flowed several sets for me and others.

X2 that’s the route I’d go so when you reinstall once you get them back you know first hand their gonna be right. Heck even ordering new ones you still don’t know what your getting or if your gonna have failures.

DrFeelgood 03-27-2022 12:40 PM

Plug wires all checked out OK. 14K-20K ohms, proportionate to length.
Caps and rotors weren't terrible but weren't new either. Port was worse than Stbd, fuzzy terminals inside, Stbd rotor wasn't seated fully on the dist shaft so the rotor plastic was rubbing the cap plastic.
Both distributors a little crusty inside.
Stbd distributor cap mounting screw holes were drilled out at some point (maybe secondary to cross threading?), so there's locknuts on the screws holding the Stbd cap down, and that was fun.



articfriends 03-27-2022 01:11 PM

Sent you a message on injector service. The "32" psi you seen, was that at wot when it wouldnt pull at 4000 ish? Bad regulators usually allow fuel pressure to drop to about 26/28 psi at wot, with your cool fuel pumps, with no vacuum, you should be around 38/39 psi , 35 MININUMUM, Smitty

DrFeelgood 03-27-2022 01:23 PM

Well, I wasn't able to monitor FP at WOT because my gauges are in the engine room on the end of the fuel rail. But at idle with vacuum line removed they are at 32 psi or so. With vacuum line connected they are more like 26 psi at idle.

SB 03-27-2022 01:34 PM


Originally Posted by DrFeelgood (Post 4826656)
Well, I wasn't able to monitor FP at WOT because my gauges are in the engine room on the end of the fuel rail..

Next time : Cell phone on record. :)

DrFeelgood 03-27-2022 03:58 PM

I decided to see if my fuel pressure gauges are actually even accurate at all... just to see if I'm chasing a red herring there. With my air compressor regulator set to 40 psi, one fuel pressure gauge reads 38-39 psi (close enough). The other reads 30 psi! Not close at all.

I'm sending both gauges back to the manufacturer tomorrow, so they can address the issue. Not going to touch the regulators at this point.


TomZ 03-27-2022 05:14 PM

I'll bet the injector service and ignition tune up will restore the lost oomph. A cooler plug might help a little too as mentioned but I'd try to look at it again after a few hours of running with the injectors done.


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