51 Hatteras 8v92T fuel issues

[Waterdog]

So today I had a rookie mishap, I think. I started the boat, and she ran fine for about 3-5 minutes, then the port engine shut down. I went below and found the fuel manifold we switched off. I then checked and found the Racors were still full, but the secondary filter was dry. I refilled the secondary filter, and the engine will not start. A) not sure if I'm missing something but how can the Racors be full and the secondary go dry, B) is this just a repriming issue? Thank you in advance for your time and input.

[Captain Ralph]

The Racor bowls show fuel but the tops are empty. Charge all filters including the Racors with fresh fuel and try again.
Be patient, Detroit star gear pumps don't pump air well.
Would you have a priming pump?

[Waterdog]

Thank you, Captain Ralph, I am hoping to get borrow a pump tomorrow morning. I will try you advise. I truly appreciate your time

[Boattrash]

I recently did the same on a set of 12v92’s. Pain in the butt.

[Pascal]

A priming pump is a must have in my opinion, cheap and easy to add. In a bind you can use pretty much any electric fuel pump even an automotive pump. Remove the hose at the racor inlet and temporarily insert the fuel pump between the hose and the racor. Doesn’t have to be fancy, you can even clamp the hoses over the threads or over the fittings. Run the pump for a couple of minutes. Crank the engine and after it starts turn it off after a few seconds. Remove the pump and reconnect the hose.

[Fanfare]

Fanfare did not come with dual Racors which I added later after a few fuel issues. As these were among my first modifications I mounted them fairly high on the aft ER bulkheads (but leave room to change the filters). I find that just topping the Racors off with diesel seems to fill the downhill lines and the pump. The fuel pump is just a little metal star wheel turning in an offset chamber, squeezing the fuel to the injectors. It doesn't suck well in air. I added manual priming pumps on the engines when I repowered but I can't remember the last time I used them. Worked for Detroit 8V-71NA and 6V-92TA engines.

[Bob Quinn]

Just turning a priming pump on might not be the whole story. If there is air in the line above the filter and in the fuel pump the air will likely prevent the fuel from filling the lines.
When I had this issue I had to crack loose a fitting on the outboard side of the fuel pump.

Air would bubble out of the fitting for about a minute or two while having an electric fuel pump pushing fuel into one of the filters. I have another post on here with pictures showing where I hooked up the pump and where I cracked the fitting loose on the fuel pump.
Hope this helps.

I got the pump at an auto parts store. They all seem to have them. Fortunately I also have a 12v battery in one of the engine rooms for a close connection for power to the pump.

Feel free to call if you are having trouble, I might be able to help.

[rsmith]

Never heard of a 51 before.

[Waterdog]

So, I followed Captain Ralphs advise, I installed a temporary fuel pump between the tank and Racors, turned it on for about five minutes to until I could hear fuel going back to the tank and she's back to purring like a kitten. I get a lot of great advice from this group, and I can't thank you enough.

[Bob Quinn]

Also, basically that is what mine was doing. It would run for about 7 minutes then run out of fuel.
After finding a couple of leaks the problem went away but it still did it one more time after sitting for about a week and a half. It would always start, then runs for a little while and then would stop.

I know your issue is different but interesting how the symptoms are similar indicating a similar air block.