New owner questions

[kwiksilver]

I did a bunch of searching but couldn't get all the answers I was looking for. I have been having the "low rpw" problem since I've had it but today it threw me a curve ball. I was going to get filters but I was getting plenty of return fuel to the tank so I was hesitant to change them just yet. Now the curve ball... I was free revving it today to check the governer when I noticed it would get to 2k at full throttle then jump up to 2600. I let it sit for a little while and when I went back it would rev to 2600 with no hesitation so I took off to drive it and back to 2k rpm's. When I came back from the drive It would rev to 2k and hesitate for 1/2 a second then 2600 pretty regular. There is some resistance for the last inch of pedal throw in the cab but I chalked that up to sticky mechanism in the pedal... or maybe not? What do you guys think? Thanks

 

[Barrman]

Change your fuel filters. All 3 of them. Return fuel flow just means not all that is being sent to the IP is being used at idle. It doesn't mean the IP is getting enough for full throttle. By the way, full throttle should give you a governor stopped top rpm of 2830.

There is a great manual in the resource section called "Trouble shooting manual LDS-465-1 Multi fuel engine." It is for the 5 ton version of the motor, but 99.99% of the manual applies to the Duece version. Download it, print it and follow it.

Air and Fuel are what make the engine run. Making sure you are getting enough of both is where you will find your problem. New fuel filters always make a M35 feel a little more frisky. Even if the old ones weren't really bad. Changing out bad ones makes you think like you have another truck pushing you down the road.

 

[rlwm211]

Although this may not have any bearing on your problem, I would offer the following thoughts:

1) What are you using to lubricate your fuel system?

The reason I am asking is that with the ULSD (Ultra Low Sulfur Diesel) your mechanical pump is not getting the lubrication it did with Sulfur in the fuel as it was 10 years ago. While there are a lot of differing opinions on this topic, I believe our pumps are operating at a disadvantage because of the ULSD and this is problematic for the entire fuel system. I have read studies that compared original diesel to the current product and then proceeded to compare the old fuel against the new with additives in the fuel. To make a long story short, here is what i do to "feed" my deuce.
I add 1.5 ounces of 2 cycle oil to each gallon of fuel. Originally, I was adding roughly one quart to a tankful, but have upped the addition of the oil as it seemed to make a big difference and I felt I needed a little more. So far all is well. The Multifuel will burn the oil happily anyways if for some reason it is too much.

2) I also add "POWER SERVICE" diesel fuel conditioner which has a cetane booster and also other additives that improve the flow of the fuel and prevents gellling. Not sure how much this does, but I have done this since I got my truck at the advice of "JATONKA" who is one of the "Deuce Sages" on this site and if he says do it, I do it, simply because I know he has probably forgotten more than I will ever know about my deuce.

It is possible your injector pump is suffereing from the low sulfur fuel and a shot of oil in the fuel may help. I also know that in the injector pump some other issues can crop up that are not specifically fuel related.

My suggestion in summary is to get as much support from all of the folks here and then you may want to try some, or not, but at least you will be working with more ideas than you have now.

Best of luck and I hope things work out easily for you!

RL

 

[DeuceNewb]

change the fuel filters.

 

[kwiksilver]

Will do. Also, the resistance at the end of the throttle is the spring stop on the IP. clever engineers!

 

[gunboy1656]

rlwm211, said it as good as I would.

Also change the filters anyway, so you know they were changed recently.

 

[Ord22]

change the fuel filters.

 

[bratpackdad]

And while your down there switch to spin on filters.

 

[kwiksilver]

Saweet! All filters were jammed up with this thick chewy goopy residue. What a mess. The pump screen was almost completely blocked. I don't know what Warner robbins used for fuel but it sucked! Thanks for the info guys.