Wierd Idling & Reving

[dieselgiant]

My Rebuilt pump has 9000 miles on it and its not acting right. What it does while its idling and I put it into gear the revs drop from 800 to 500 and come back up. Same thing when I rev it and it settles back down it will drop to 500 or 600, depending on how High you rev it, and it comes back up to 800. It's never done this, ya'll know how automatics are when you put them in gear they just put a load on it and the rpm's drop slightly. I've also noticed that there is not near as much smoke as it used to have at WOT still has the power but just a haze This all seems to have started after I let it set for a month. The fuel blend that it had at the time was about 40/60 wmo/diesel. I changed the fuel filter yesterday, been running diesel for 500 some odd miles since it sat, no return line leaks, fuel pressure is 5psi at the filter head, did the volume test(past), the timing mark have not moved, and I've run a healthy dose of ATF through it. I'm thinking the governor how ever it works is getting weaker or sticking??? WMO side effects or 4200rpm gov setting.

Oh and the fuel mileage is extremely bad, and it starts very easy at 40F Going on a long trip Monday towing some ones car to S. Carolina and i don't want to have any serious break downs. Should I be concerned.

 

[94turboidi]

I tried running some waste motor oil after using waste vegetable oil with good luck. I started having trouble running even diesel after awhile. When I finally changed my fuel filter after running alot of diesel through there it still had black oil trapped in the filter. I had filtered the oil down to 5 micron before it went in the truck also. The truck ran great after I switched filters. I was having some weird idling problems at the time also when running the oil.

 

[dieselgiant]

interesting I never had any issues when running 90% oil, and yeah that black stuff stays in there a long time but I'm shur that its thin enough now to not cause problems maybe.

 

[94turboidi]

I was running it 100 percent

 

[m67tang]

My truck was idling all over the place two weeks ago, maybe like yours??? I replaced the lift pump- problem solved!

 

[icanfixall]

Get some fuel treatment called Howes or Stanadyne ... Run that at a double dosage amount... I run 4 ozs of stanadyne performance in every tank full of staright diesel... Never have run the junk fuel... I invey those of you that have and gotten away with it safely....

 

[opusd2]

I run a concoction of Isospropyl and Power Service with every tank, and have for the last couple of tanks have added to that some Howes and biocide, just to get ready for winter. I will admit to running ATF before all of this for the lubricity, but right now the Howes and Isopropyl, while it may be overkill, is a great combination. I just ran my tanks down to see what I would get, and other than a fuel filter I know needs replacing, with my 4.10 gears and occasional 65 mph in order to not get killed on the highway, I got 17 mpg. I will NOT complain about that.

 

[paulb3]

I've had the similar problem and seems to be an indicator that the govenor in the injection pump is having issues either from something making it sticky that can be sometimes be cleaned out with various diesel additives. I used Diesel Purge and started running B100 biodiesel again and it seems much less severe than before but I am still going ahead and replacing the IP pump because the truck has over 200K miles and the pump was replaced once already so I think it might be time to change it out again.