Injection pump intake pressure

[Jefff27]

One of my 7.3 idi is the marinized version done by star Pwer (correct spelling). I put in a new electric fuel pump in preparation of this years boating season. In my truck I run the same electric fuel pump set up with no problems. It will give me about 8psi. In the boat the pump is much closer to the engine and it does not have to push the fuel up hill so I am getting around 12 psi. I am considering a fuel pump regulator to bring this down, but besides my fear could I be doing the pump harm with that much fuel pressure. She started better than ever before with my pre season shake down starts, but this concern me. Been a fan of this forum for a few years now, but the first time asking the question.

Am I hurting the injection pump by putting around 12 psi to it?

 

[Clb]

Hit the stickies, mel(agnem) has a primer on this

 

[snicklas]

@Thewespaul

What is your thoughts? A marine pump should have similar requirements as the truck ones. I just wonder if it has an Ag style pump, timing wise.

@Jefff27

Can you give us the spec and calibration numbers off the tag on the pump.

 

[Thewespaul]

If it is a marine turbo IDI it will be a db2-831-5090 pump. They are calibrated same as the on road pumps, 5-6.5psi is spec. You won’t harm the pump with that much inlet pressure, but it will throw the calibration off so it’s best to set the pressure lower with a regulator.

 

[icanfixall]

Agree with the above posting. Get the pressure reduced for the best injection pump use....

 

[Jefff27]

I have to say, this site is amazing. The engine does not have a turbo, but I would assume the same answer applies. Thank you for the quick response. I will put a fuel pressure regulator on it, but it is nice to know while it is being delivered I can continue to check everything else without fear of harming the pump. I will add a few things here for the fun of it. I had a heat soak issues when I first bought the boat, I pulled the pump and brought it to a reputable rebuild shop. Keep in mind the engine had 400 hours on it at the time. They said it was tuned to a 6.9, not a 7.3, but otherwise no problem with the pump. I thought that was interesting. I also continued to have the no hot start issue. My only fix was to install a bilge fan to blow cool air on it to help it cool properly. I had come to the conclusion it was a design flaw in the boat. The boat is a custom built commercial lobster boat and the dog house sits about 13" above the floor trapping the heat. I have thought about rebuilding or replacing the pump, but I think the same problem would be there. The fan does the trick. I have since put another 1000 or so hours on it with no change, still runs great for 8-10 hours at a time. I figured I would through that out there to see if anyone else would agree.

 

[nelstomlinson]

Usually hot start problems are a worn pump, everyone says. I deal with it by pouring a quart of water over the injection pump before I try to start it.

 

[Thewespaul]

Most shops are not familiar with these pumps at all, they predate most fuel techs now days. If your engine has only 400 hours on it I highly doubt the pump had been pulled rebuilt and recalibrated to a 6.9 (lower house spec) more than likely, the original pump failed and a used pump was installed. The hot start issue is due to your head and rotor assembly not making enough pressure at cranking speed to open your injectors. That could be because the pump is worn out, or that you’re just not cranking quickly enough. You should have at least 150 rpms when cranking, better around 250.