93 S/N erratic gauges

I have a new-to-me 93 SN with the standard 351 motor (not GT, not EFI) and upgraded to protec.

I have three gauges on the dash that have issues:
- RPM reads significantly low. at WOT it displays 3500. At idle it'll show 400 rpm. It seems to stay consistently low, and doesn't fluctuate or bounce around

- temp gauge will often display 220 or higher. tapping on it drops it down to 170

- fuel gauge shows full when it's full, then within approximately a gallon or maybe two of usage it'll show 2/3, and drop fast to 0 from there. I've run it so it won't bounce off 0, then filled it up, and it took 22 gallons, so I still had 5 gallons in it


I've read that 93's had common issues with these gauges, but I'm not finding via search any standard fixes for each. Any suggestions?

Your idle needs to be adjusted on your carb to idle at about 750 rpms. These engines have govoners on them. My 351 wide open is in 3800 range. Fuel gauge may be ground or the sender and same with temp. Temp should run in the 155 range. Lots of things to eleminTe. These gauges are pretty good. I'd trace issues back to gauges- versus going from gauges back. Good luck!

These engines have govoners to protect engine. My 351 runs at 48mph at 3800 rpms. It had a 6k tach and you'll never reach that. My bit runs and performs great. Prop could play a role as well- but my boat is 100% original factory. Has 51 original hours on it.

I was wondering the same too!

I emailed PCM rep and he said the max RPM on a 351 is 4400. I miss spoke. He said prop

Prop on my 1991 excel is a 14 x18. Running original pro-tech -and it is carboarated.

The prop would be the variable is what he is saying. The engine maxes out at 4400 rpms.

That's how it was set up from the factory. Best of luck solving your issues. Enjoy the water

To underturn rpm vs Mph takes cubes, or an efficient hull. All 285+ hp (HO) fords want to spin 4800 or so, 5k is fine.

Above numbers are garbage. Tach or speedo is wrong (48mph @3800).