Ultraliner 2 Posted January 9, 2013 Share Posted January 9, 2013 Hi i have a 400 v8 in a 85 superliner that has been sitting for a couple of years before i bought it when you start it idles fine but as soon as you accelerate at about half revs it takes off and revs to full revs and wont deaccelerate have to stop it on stopper then it starts idles ok then if you rev it at half revs it takes off to full revs again thoughts please Quote Link to comment https://www.bigmacktrucks.com/topic/29269-v8-400/ Share on other sites More sharing options...
farmer52 Posted January 9, 2013 Share Posted January 9, 2013 Sounds like a fuel pump governor issue (rust from sitting). Likely you need to have it rebuilt. 1 Quote Ken PRR Country and Charter member of the "Mack Pack" Link to comment https://www.bigmacktrucks.com/topic/29269-v8-400/#findComment-156120 Share on other sites More sharing options...
slpwlker Posted January 9, 2013 Share Posted January 9, 2013 Welcome to the jungle. Lets see some pics. Oh and I have no clue Quote Link to comment https://www.bigmacktrucks.com/topic/29269-v8-400/#findComment-156146 Share on other sites More sharing options...
Brian Blaylock Posted January 9, 2013 Share Posted January 9, 2013 More than likely the governor needs rebuilt I had a endt 865 with the same symptoms and a governor rebuild fixed it Quote Link to comment https://www.bigmacktrucks.com/topic/29269-v8-400/#findComment-156199 Share on other sites More sharing options...
theakerstwo Posted January 9, 2013 Share Posted January 9, 2013 What i would do before you lose the engine get some to open the governor and check and see if the rack is stuck or sticking Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/29269-v8-400/#findComment-156200 Share on other sites More sharing options...
rsb502 Posted January 9, 2013 Share Posted January 9, 2013 if its an 85 E9 400 its probably an AMBAC pump, remove the 6 bolts on top of the cover at the back of the pump (cut the lock wire) then you can look down into the governor housing, move the rack by hand to make sure it moves freely and returns to idle the stop arm is on the right side you can actuate it and the throttle arm on the left side and watch to see if the rack sticks, also check to make sure its not the throttle arm return spring broken or missing if so as the rack is advanced by the puff limiter as the rpm increases it can push it past your input on the pedal, then when you grab the shut down knob you pull the rack back the other way. just my two cents, oh and if you back off the nut on top towards the back of the engine and tighten the one towards the front of the engine you are adjusting the rack stop for more fuel. Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment https://www.bigmacktrucks.com/topic/29269-v8-400/#findComment-156222 Share on other sites More sharing options...
fjh Posted January 12, 2013 Share Posted January 12, 2013 Also the older pumps have a slip clutch on the pump cam ,if the clutch gets worn the engine can over speed if your simply going to governed rpm your golden, if its going over the governed speed be carful not to be stomping on the throtle as it reaches top rpm It may not come back down! Its possible its a sticky rack or simply a throtle cable / lever issue operate it at the pump and see what it does ! Quote Link to comment https://www.bigmacktrucks.com/topic/29269-v8-400/#findComment-156805 Share on other sites More sharing options...
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