More power from M11

J

jeffl1107

Member
Hello new to the forum.
So I have a 1994 Ford L9000 Mobile Home Toter Truck that I pull mobile homes, offices and modulars with. Its a single rear axle truck with an M11 mechanical in it. My question is, is there a way to get more power out of the engine without major mods. Dont want to put major money into it cause I really dont have it. But I am going to keep the truck as it only has 340,000 original on it and is a good running truck, and no payments. LOL. Anyway, I do haul in PA and NY where it can get a little hilly and would like to have more power. My truck is leased with a big company and I regularly run with other drivers on hauls. But all of those guys can simply pull right away from me anytime they want. And I would like to be able to have the option to keep up when needed. I had a mechanic drill out and turn up the fuel screw. He went 2 turns up but then the truck started smoking alot so I backed it back down. Just had 2 injectors replaced and the valves adjusted and seems to be running good. So just thought I would ask others thoughts on the question.
Thanks
 
J

jeffl1107

Member
Well now I am a little confused. I never even really looked at the motor plate because it was pretty gummed up, but as soon as I saw your message I went out there to clean it to see if I could read it. A lot of it was hard to read until I find something better to clean it up but the plate said clear as day, "L10 260". I was told it was an M11, even by the dealership. Its a 94 truck but it has an 11/93 on the plate.
 
Truck Shop

Truck Shop

Well-known member
jeffl1107 said:
Well now I am a little confused. I never even really looked at the motor plate because it was pretty gummed up, but as soon as I saw your message I went out there to clean it to see if I could read it. A lot of it was hard to read until I find something better to clean it up but the plate said clear as day, "L10 260". I was told it was an M11, even by the dealership. Its a 94 truck but it has an 11/93 on the plate.
Click to expand...
I was wondering when you said it was a M11 those are electronic engines and could be rated for 375 to 400 HP. Were you watching when this mechanic turned the smoke screw?
Check the engine serial number against the vin number/cpl and look for a date of manufacture. The L10 is no power house but it is a good engine.

Truck Shop
 
J

jeffl1107

Member
Ok tomorrow I will look and see what I can find for dates on the engine and truck. It is definitely not an electronic engine. No electronics on it at all.
As far as the mechanic, no I did not see him do this. All I know is I brought it in to him for what sounded like a miss. It was hard for me to tell unless at higher rpm with pulling a mobile home. He said it was a bad injector and swapped out 2 injectors and adjusted the valves. While it was there I asked him if he could turn it up. He turned it up 1 full turn. He said the ball was hard as crap to drill out. Never had that much of a problem except with mine, but got it out. I brought it back to him the following weekend because he had to put king pins in and asked him if he could up it a little more. He went up 1 more turn and said he really didnt want to go up much more than that. He said he knows guys that have gone 3 and over but doesnt like to do that. He is a young guy but I knew his dad that just recently died and he knew his stuff. The son seems like he knows what he is doing. But the only thing I did not like is that the truck was blowing out some decent smoke when it was turned up, especially when I got on it. So I decided on my own after speaking with him that I would back it back down. He went 2 turns and then just today I backed it down 1 1/2. So at this point it is only turned up 1/2 turn. But after backing it down it still seemed like it was smoking. Now on occasion before he messed with it, it would sometimes smoke some, white smoke, but then after a while would dissappear. But seems like since he has had it, it is blowing a little darker and pretty much all the time. I have only driven it 2 times for less that about 8 hours since he did this about 2 weeks ago. I dont run the truck every day, especially this time of year. But will be running it Wed and will watch the smoke
 
B

BoxCarKidd

Active member
You can get some fuel from the throttle shaft screw most times but I thank that was more for fine tuning. First make sure the AFC, air fuel control, diaphram and the connections to it are good. Throttle lever brakes over a least a 1/4 inch at full throttle. Air filter and anything else that can cause low power and black smoke are good first. At the back of the pump is a cover held on with 4 -1/4 inch bolts. If the seal is still on it you can assume it is set to factory specs. If the cover is removed there is a tube with a snap ring inside. If the snap ring is removed some springs, plunger, and a fuel button are in there. The button will have a number on it like 15, 17, 21, etc. the lower the number the more the fuel do not recommend dropping more than two sizes. The shims control RPM. The more the shims the higher the RPM. The thick ones are 50 RPM each and I normally added four. The screw in the end of the plunger is the idle adjustment. It requires a lot of trial and error or a special tool, screwdriver, that screws in the plug hole in the end of the cover. Then it is adjusted while the engine is running. If you get to really cranking and or standing on them you need an exhaust temperature gauge to help prevent a melt down.
There are 61 cubic inches in a liter so that is only about a 610 CID engine. If you are trying to run with the big dogs don't. You can get unbelievable fuel mileage if driven properly and let your little dog store up in the bank while the big dogs laugh at you. Just my opinion, smile at them.
 
Steve Frazier

Steve Frazier

Founder
Staff member
According to Wikipedia the L10 was available with up to 400hp. I drove L10 trucks that were rated at 300hp and they got around pretty good considering. You might run into some expense but I would imagine you could upgrade yours to higher power.
 
Truck Shop

Truck Shop

Well-known member
Like BoxCar said to increase fuel you have to change the button. But if you want more beans out of it I would do a re-rate to another CPL and have injectors and
fuel pump done together. Turning the screw in the throttle shaft won't get that done, turn it back to stock setting. Plus there is the question of the turbo on some
engines when doing a re-rate. You need more air to go with more fuel. But you can set it up 10% over on fuel and still run fairly clean with little smoke.

Truck Shop
 
J

jeffl1107

Member
Thanks guys I appreciate it. Yeah I wouldnt mind a little more power but frankly if I had to choose I would rather put a Jake on it. That is something it does not have that I really need running in the hills. I was told I need a 404B for that one and have been looking for one.
But my other question is this mechanic said he put in 2 injectors and adjusted the valves. He also said that he had to replace somekind of diaphram that had a small tear in it when he had the front cover off the engine. So when I got it back from him it has been smoking alot more. Like I mentioned previously it would sometimes put out some white smoke but would then clear up after time. But since getting it back from the mechanic, it seems to be constantly smoking and is not black, but definitely darker and really throws it when I throttle up. I did turn that screw back 2 turns so should be back at stock. I dont know what he could have done to make it smoke like this but when I asked him if the screw would do that he said, no it should not. That when I turn it back the smoke should have cleared up relatively fast if thats what it was. So when I asked him what else it could be, he answered, "Hmmmm, have to think about it". You guys have any ideas what it could be??
 
B

BoxCarKidd

Active member
If you don't find one maybe check out TecBrake. I cannot relate anything about a diaphram to the front cover? Incorrect injector adjustment can cause smoke, can't say that's your problem. Why was the front cover off? Something out of time? Sometimes disregard everything and start with a manufacturers trouble shooting flow chart.
 
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J

jeffl1107

Member
Ok will check the TecBrake out. Never heard of that. Heard of Pacbrake, but not Tecbrake.
Anyway, yes, he said it was out of time and he had hard time getting it back in time. I dont know if the diaphragm had anything to do with that or not but I am guessing so. External parts I am good working on but any internals I try and stay away from or do a lot of research before I would even attempt it.
 
B

BoxCarKidd

Active member
jeffl1107 said:
Tried to get on Tecbrake website but keep getting an error
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I looked after I posted. TechBrake only does Cummings in 855 or 14 liters. Have to get Jacobs, they made them. Some older engines smoked a bit when they were right. I have an M11 mechanical in a truck. If it is not baby footed she rolls some smoke.
 
J

jeffl1107

Member
Ok thanks BoxCar. Definitely need an engine brake. I think I will check out the button to see what is in it and hopefully get a little more out of that.
 
J

jeffl1107

Member
ONe other question. The fuel screw that he turned up, that is the one that is inside the fuel linkage shaft that he had to drill the ball bearing. When he told me he turned it up 2 turns, does that mean he turned it 2 turns "clockwise". I see some posts, not sure if they are referencing that screw but the say to "turn it out" a couple turns. Out to me means counter clockwise. I want to make sure because I backed it off 2 turns which means I turned it counter clockwise.
 
Truck Shop

Truck Shop

Well-known member
Here is a full animated video of the operation of the Cummins PT pump. It explains about the screw in the throttle shaft and its calibration, plus the problems
that can occur when out of calibration. Plus this video gives the full explanation of what the governor and fuel button do. You will have to ask your mechanic
which way he turned it { in or out }.

https://www.youtube.com/watch?v=KzuwdxEJfQA

Truck Shop
 
J

jeffl1107

Member
Cool video. Learned alot I didnt know, but still have a question. Maybe I am just missing it but when they start talking about the fuel adjusting screw around minute 13, I do see where they say it is used to calibrate rail pressure. But it also seems as though that adjustment is on the inside of the shaft. Am I wrong. The video shows the linkage arm on the other side of the shaft and they never mention any adjustment behind the ball bearing.
I will ask him which what he turned it. Maybe you can figure it out but this is what he wrote me when I mentioned I wanted to turn it back to stock setting.
"If you look dead center of where the linkage hooks to the pump, almost level with the top of the frame. You will see a hole with a screw in it. You can turn that to the right 1-8 to a 1-4 turn."
 
Truck Shop

Truck Shop

Well-known member
The rail pressure setting at the throttle shaft is calibrated on the test stand and is not meant to be adjusted later. That is why they seal it with the ball.
Changing the button how ever will increase the rail pressure by not letting as much fuel bypass the governor plunger. If the stock button let's say is a
#25 and you install a #20 you have increased the fuel and psi by 10%.

Truck Shop
 
J

jeffl1107

Member
Ok I would like to change the button. I think it was mentioned earlier to go down no more than 2 sizes. But first I want to see what that mechanic did with my fuel adjustment screw. Like I said I turned it counter clockwise 2 full turns thinking I was putting it back to stock setting from him turning it up. But from what I have seen on the internet, "turning it up" actually means turning it counter clockwise to let more fuel threw. I will have to see what he did but I would he assume that it turned it counter clockwise 2 turns which would mean it is now 4 turns which I have heard is to much and can possibly damage the cam over a period of time. But before I jump to any conclusions I have to get in touch with him. I have been trying for about a week now. I appreciate all the help.
 
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