Odd power problem

[armadillofz1]

i've only owned my deuce for a few weeks now, but have over 500 miles on it. i've noticed that it's fairly down on power and won't rev passed 1800 in the first 4 gears, oddly 5th is fine and pulls harder than 4th. bizzare. now on the last few days it's been running great and pulling like it should, very strong in all gears. then today back to it's problem. not sure what to make of it. does this sound familliar or common among m35a2s? just trying to get an idea if so before i go replacing all the fuel filters, air filter etc... i know the in tank fuel pump is working, turbo sounds like its spooling up. first though was to check the air filter but the problem wouldnt've cleared up and then returned if it was the air filter.

 

[tm america]

check those fuel filters thats ussually the problem

 

[m-35tom]

replace all 3 fuel filters, make sure copper fuel line under front engine mounting crossmember is not smashed flat.

 

[rideni]

fuel filters

 

[Castle Bravo]

Since no one has said it yet, check the fuel filters.

A while after I got my Deuce, it was doing this same thing. Changing the filters solved the issue.

 

[actionfigurebob]

Did'nt we have this discussion on the phone the other day?

 

[armadillofz1]

Did'nt we have this discussion on the phone the other day?

i know. i'm swapping out my fuel filters out this weekend, i just figured i'd poll the masses here, seems unanimous. still befuddled why 5th gear would be any different.

 

[bgekky3]

Check to make sure the throttle return spring is the correct one. On my last truck it was way too stiff and I couldn't go over 2,000 rpm. After turning up the fuel, and looking into the governor settings. We changed it out and it solved the problem.

 

[armadillofz1]

ok update. fuel filters changed, in tank fuel pump screen cleaned (yes it was clogged pretty well), and one small kink in the fuel line un-kinked. air filter looks fine. in tank fuel pump pumps strong (like a garden hose) truck revs fine now but still wont pull as strong as it should.

my litmus test has been the hill leading away from my driveway. when i first noticed my problem i'd have to down shift to 3rd to make it up, when the problem mysteriously cleared up for a few days it would pull it in 4th and even accelerate a bit. now back to 3rd.

i did blead the system after my filter changes. wouldn't any small missed air bubbles blead them selves out after the truck started?

i did originally have diesel in the truck when i bought it and drove it 200 miles home from New Joisey, then noticed the problem while still on diesel. then i aquired a few hundred gallons of heating oil (#2 Diesel). I filtered it and filled up on that. i ran it for a few days and thats when the problem cleared up. then it came back and that's when i started changing filters and such. i chalked up the performance improvement to the heating oil not being ultra low sulphur, and having beter lubricating properties. but that appears to not have been the case.

i'm guessing my next check should be the injectors. anything i need to know about cleaning them? thought about taking them to my old job and cleaning them in the ultrasonic cleaner for half an hour or so. would that do the trick or should i just replace them?

 

[gimpyrobb]

Alot depends on how long you have run it. I notice that my LDS and LDT trucks don't have the power at start up as they do after I have been driving for a while. Have you taken it out for a good hour long drive since you changed the filters? A deuce that isn't driven much, needs to be DRIVEN. I have heard that in most motors, the injectors need cleaning, so that might be a good start for further trouble shooting. Have you installed a pyro?

 

[armadillofz1]

yeah it takes me about 10 minutes just to get down my driveway and to the base of the hill. the truck is up to temp by then. i drive this thing pretty much daily now (untill the novelty wears off, not likely, i know)

 

[Keith_J]

Injectors don't fail by clogging, they fail by wear and start leaking or poor pattern. Poor pattern is most noted at low power levels like idle speed stability.

Since these nozzles are 2-hole, they are most probably good unless this is a very high mileage engine.

This could be injection timing, not the base timing but rather the automatic timing adjustment which is handled by the front end of the pump, near the front of the engine. It is a simple centrifugal unit but repair requires removal of the IP from the engine.

Here, a pyro will show this as an increase in EGT. Since the heat energy of the combustion would happen later with retarded timing, less energy goes to the crankshaft. Conservation of energy dictates it will go out the exhaust valve, heating the head and the exhaust system.

 

[armadillofz1]

does this seem indicative of my problem? clearing up then back to lower power?

 

[Keith_J]

Certainly could be the injection centrifugal advance unit. The key sign that timing is retarded would be EGTs higher than normal. Have you noticed any additional smoke/heat? Like paint on the exhaust burning/smoking.

Now root cause? The mechanical internals of the pump are lubricated with engine oil. The oil enters under main gallery pressure but drains by gravity. If the drains are crimped/clogged, oil level could increase, causing issues with the advance flyweights. This is easy to check, just a bit messy.

 

[armadillofz1]

no effected paint from heat. exhaust pipe doesn't seem any warmer than usual, i can usually touch it after a few minutes of turning it off. i'll check for any pinched lines. looks like i have a date with the service manual. thanks