1996 Monaco dynasty

[Tarezzi]

I’m new to this forum so go easy on me.

My problem is I have a 8.3 Cummins mechanical lose of power I was a member of another forum who were all more then helpful. But after doing everything that was suggested still the same problem. I am new to diesel but I was a owner of a automotive repair shop some 20 years ago.

My problem is we were out on a trip short one 600 miles going up ran perfect lots of power boost 21 psi, when coming home was running fine 70 plus the last 10 miles had lots of traffic right  before my house there is a steep hill that I barely got up. Was just happy to be home now here’s where my adventure starts the next day I try to see if anything I could see obviously. I joined a pay as you go question site wow 3 questions later 90 dollars poorer nothing. Here’s what I’ve done so far had cac hole welded no difference then changed all rubber hoses no change removed waste gate unfroze pac brake replaced exhaust manifold new turbo. The last thing I did this morning was put in a new lift pump well no surprise nothing. I read some interesting stuff here and am hoping someone has something that maybe I missed. My tach is 2500 rpm and boost is 5 psi also I knew I missed something a new rebuilt king controls unit sorry this is so long but didn’t want to waste anyone’s time by stating something I already did  thank you all in advance for any help 

[jleamont]

Tarezzi, Welcome to the FMCA Forums! Sure sounds like you have been through a lot with this unit so far. Have you tried replacing the fuel filters (I didn't see that mentioned above)? Can you measure fuel pressure after the lift pump (T a gauge into the line)? 

[hermanmullins]

Tarezzi,

Welcome to the Forum or should I say the free Forum.

If you just started to low power on take off but were able to get up to speed and the engine is just sluggest I would change your fuel filters. Dirty filters will cause the power to decrease and finally stop. When you remove the filters look closely to the top of the filter for foreign matter like gumand sludge. 

It is a cheap fix even if it doesn't help. It's like giving chicken soup to a dead man, "It may not help but it could't hurt."

Herman

(Joe got there while I was typing)

[Tarezzi]

Sorry guys hanged both filters this has a Wynn fuel filter I put a racor filter on the back yea I thought I listed everything 

[rls7201]

Are you blowing more black smoke than normal? More smoke = boost issue. If no excess smoke then you're not getting fuel.

 

[jleamont]

3 hours ago, Tarezzi said:

Sorry guys hanged both filters this has a Wynn fuel filter I put a racor filter on the back yea I thought I listed everything 

When you are pulling a hill, what color smoke (if any) do you see? 

Another check, rev the engine sitting still, does it break up and smoke, if so what color? 

You have the most simplistic engine given its a mechanical injected engine, so some basic checks could point this in the right direction, with your mechanical aptitude you'll pick it up quickly. Its such a simple system you might over think it.

• Low fuel volume to the lift pump, could be a failed fuel line between the pump and tank sucking air. You could try a new hose into a 5 gallon jug and see if power is restored.
• Blocked/clogged fuel system, algae and other crud is not uncommon. Older Monaco's utilized rubber fuel hoses that would breakdown over time and collapse and clog the main feed line between the tank and lift pump.
• Fuel injection pump needs rebuilt. This is fairly common as the new fuels eat up the old style components within these pumps. Since this is the most expensive lets table this for the time being. We don't want to open this door unless we have exhausted all other checks. 

[Tarezzi]

There is no smoke and I have read a lot about fuel lines just replace the lift pump this morning. Maybe someone can tell me or correct me if I’m wrong but one line goes from tank to lift pump ? Where does return line come from that goes back to tank I can see where the lines are going into the tank

[jleamont]

Correct, one line from the tank to the lift pump. The return line should come off of the cylinder head and go to the tank. There is usually a check valve on the back of the cylinder head between the line and Head. You could also pull that, make sure it clear and not stuck open.