low rpm quiver

[jheath]

I have a 94 2500,at 1000 to1250 rpm's especially in higher gears the engine shakes,as if it were missing butI don't think it is a miss. It feels as if it were lugging,but it does it even with just slight acceleration. It has done this ever since I've had the truck. I thought the injectors needed to be set. Did help some I believe. Next I set the valve clearence. did'nt help. I removed the pump and had it checked. It was O. K. They put a new overflow valve in. When I reinstalled it ,the problem was gone for one quick trip,but next trip it was back. power is fine. Has anyone heard of this?

 

[Jeff H]

Same problem here. Mine truck will shake from 1000 to 1200 rpms on light throttle. I had injectors tested they were fine. Timing made no difference.

I'm leaning towards possible airiated fuel. I think I might be pulling tiny amout of air into the fuel. The reason I think this is becauese after I had injectors tested It ran smooth for about 500 miles then started too get noticeabley rough again.

Some people say that the return line admits air even though the rubber line looks in vary good condition. I think my problem my be in the fuel tank. When its full it seams to run smoother. When it starts to drop down it seams to get rough again. But usually when air is being introduced into the fuel. The engine usually starts harder. Mine starts fine.

 

[Missouri Mule]

There is a possibilty that the quick disconnects on supply line at fuel tank(fuel module) mite be pulling air in.

Except that our fuel system is supposed to get rid of the air.



A ford man checked then changed connectors , he put rubber hose and screw clamps at tank and re- worked the rest of fuel system (new lines/regulator) because the quick disconnects were pulling in air( supply line only).

Also the ford fuel system did not have return fuel line on injector pump.



When I find some time I 'm going to get a rubber hose and a couple screw clamps and re-do the supply line connection at the fuel module.

 

[snake]

Originally posted by Jeff H

Same problem here. Mine truck will shake from 1000 to 1200 rpms on light throttle. I had injectors tested they were fine. Timing made no difference.

I'm leaning towards possible airiated fuel. I think I might be pulling tiny amout of air into the fuel. The reason I think this is becauese after I had injectors tested It ran smooth for about 500 miles then started too get noticeabley rough again.

Some people say that the return line admits air even though the rubber line looks in vary good condition. I think my problem my be in the fuel tank. When its full it seams to run smoother. When it starts to drop down it seams to get rough again. But usually when air is being introduced into the fuel. The engine usually starts harder. Mine starts fine.

Did you find the problem with your truck ranning rough at 1000 to 1200 rpms?

Thanks, David

 

[bighammer]

My 94 does that too. I notice it most coasting thru town when 3rd seems too low and 4 th is too hi. I'm trying to stick to 3rd and keep the rpms up even though there is not much load on the engine.

 

[illflem]

bighammer has the solution. It sounds to me like you other guys are lugging your engines. Even my Toyota will shake if I give it gas at 25 mph in 5th gear.

 

[Dennis Garrett]

My problem is at hot idle. It idled fine, then I added 215 injectors, and the 3k GSK at the same time. Now after it warms up, the whole truck shakes. I checked the valves, & found a few that needed slight adjustment, but it didn't help. Under load, it smooths out, & runs smooth as butter on the road. I've tried higher & lower idle speed, but it doesn't help. Starts good, and sounds fine until it gets good & hot, then it shakes the truck, reminds me of the big cam chevy's back in the 60's!

 

[MDW]

I believe your problems are the govener.

Post your signatures (year and injectors).

When you change injectors on the 160 and 175 pumps it freaks out the govener, especially the 160.

 

[bighammer]

I've still got the stock injectors. ('94 w/109k)

 

[BCFAST]

You chaps have done a FABULOUS job of describing my truck!! After chasing this for 8-9 months(!!!) I am no farther ahead; I have changed injectors, overflow valve, rebuilt the pump and governor, changed the clutch assembly and flywheel balance, valve adjustment, timing changes, and gobs of hours of fooling with it! I shakes from 20rpm over idle, right thru redline... any load, any speed, any throttle position. My mileage has dropped about 2mpg. Just yesterday I had the idea of aeriated fuel... even though my lines look good. I will be changing the lines and clamps. Best of luck to you all... . I know it's frustrating~!

 

[Jeff H]

Snake your mailbox is full.

Get that junk mail out of there.

 

[bighammer]

BCFAST, mine is only at about 1000 to 1200 rpm. Not sure what you have, but it sounds different.



I wonder if your compression is un-equal, or something like that. Might be something to check. Good luck

 

[snake]

Originally posted by Jeff H

Snake your mailbox is full.

Get that junk mail out of there.

Jeff H, mail box is clean

 

[SReeves]

my truck did the low rpm shudder and i had diesel dynamics figure it out. turns out a bushing was worn out,part of governer asssembly. that shudder drove me crazy,I'm much happier now

 

[Reddog1]

throttle cable related?

About three weeks ago, I had my throttle cable replaced as per recall (’96 Ram). After having this done, I am experiencing the same thing as you guys, including the loss of two MPG.



Is this a coincidence, or could there be something related to the throttle cable that I can not see?





Wayne

 

[Hummin Cummins]

I have the same problem Dennis does. It will idle smooth as silk at start up. If I sit waiting for turbo cool down thats when it will shake, just like a big cam gasser. Give a little throttle and it smooths right out.