Community Forums

len6629 · 09-18-2018, 08:14 PM

I have a 1994 Dynasty that I just realized has a defective fuel gauge. I ran it out of fuel. So because of the age I decided to replace the fuel supply hose. At the tank the hose is 3/8 but its 1/2 at the lift pump. So I ran a 3/8 fuel line under the coach and and adapted it to the hose on the lift pump. Bled the system and it fired up and ran fine. But now i am getting fuel returning back from the old hose and its under pressure. What gives???

Skip426 · 09-18-2018, 09:19 PM

Cummins engines of your vintage ,I believe used a P 7100 injector pump and should have a line that returns fuel to the tank and someone may have tie it to the inlet side , perhaps where the line changed from 3/8 to 1/2 "

I'll see if I can find a fuel flow diagram.

EDIT : Found a diagram , the small hose shown in red , is the return line from the injector pump should run to the tank ,.

len6629 · 09-19-2018, 08:59 AM

I found the return line on the pump at the front of the engine on passenger side. What’s blowing my mind is the tank connections It has pickup and return for gen set. It has a vent hose and one other 3/8 in hook up. I assumed this is the fuel supply but where is the fuel return hook up. Certainly they didn’t use the same connections for the feed and return. I’m gonna need a stiff drink before this is over.

Skip426 · 09-19-2018, 09:56 AM

Quote:

Originally Posted by len6629

I’m gonna need a stiff drink before this is over.

Only one ???

Over 8 years, owning current coach , and still finding things that have me scratching my head , but sometimes I can't tell if the issues are factory , or mods done by previous owners.

dix39 · 09-19-2018, 11:05 AM

We just got one of the things too ('94 30' Dynasty) and I'm searching for every bit of information I can find about it for future reference. Thanks for starting this thread, and also thanks for posting the fuel diagram.

Steve

Skip426 · 09-19-2018, 11:20 AM

Len and Steve , it's important when asking questions about your engines to include that it's a 12 valve , mechanical fuel injection engine , as over the years Cummins has used 3 different fuel systems on the 8.3 and 4 on the 5.9 that I'm aware of .
So if a member with a newer coach and engine gives you hints on repairing a problem , be aware that their fuel systems could be entirely different that yours.

Setting up a signature line , with this info in it , will save you typing it in every time you have a question.