Missing on the freeway, blue smoke.
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Missing on the freeway, blue smoke.
hi all, i am new on here, looking for a little help, i own a 1987 f-350 with a 6.9. when driving down the freeway at 60-70, if i dont have a load on the truck(just lightly pushing the gas pedal) it will begin to miss and seem like it is running out of fuel, and a blue/white soke comes out of the exhaust, i have replaced the injectors because they were in bad shape, i am afraid it is the injector pump, but i dont know. when this problem starts, if i pull over and push in on the bleeder valve that is located on the injector pump, there is alot of air coming out with the fuel, could this be a bad fuel line? i hope someone can help me that might have had past experience with this issue, i am a diesel mechanic, but know nothing about the old 6.9 except they are a work horse and seem to never die. once this happens, it will idle fine, but if i take the rpms up aboue 1400 not in gear, it sounds like it is running out of fuel and will push out alot of blue/white smoke, it will slowly clear up until i have another long drive. i am really stumped here and honestly cant afford an injector pump anytime soon. thank you -Shane-
oh and ps, i did a puel pressure test going from the fuel pump to injector pump. between 2 and 4 psi
oh and ps, i did a puel pressure test going from the fuel pump to injector pump. between 2 and 4 psi
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Joined: Jan 2005
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It does sound like a fuel delivery problem. How long since you changed the fuel filter? Have you checked the water seperator, these have a problem where air can leak in? It is a canister that should be on the drivers side firewall close to the fender. It will have a ring pull on top and a length of pipe from the bottom. Use the ring pull to empty any water out of it and then block the end of the hose, incase the valve is leaking. Did you check the fuel pressure at the bleed valve on the filter head? It seems a bit low, check it again after blocking water seperator drain and if necessary changing the filter. Finally post this on the excellent pre-powerstroke diesel page, just down a bit from here. You will get plenty of replies and you can use the search on that page for information on testing your lift pump for flow as well as pressure.Good luck.
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ok, i will post results there, and yes, i did take the fuel pressure reading from the head of fuel filter, and the filter was just changed, and it still has same problem, today i was driving down the cajon pass and i let off the gas for a little bit and it instantly started running bad when i lightly applied the gas pedal, but if i floor it, it clears up, but i know it is running lean because it is not covering the lane next to me with soot.. as it will when running right. it just puffs a little blue/white smoke and when i have the pedal on the floor, it has no smoke at all.. but i will test the water seperator, i am planning on running a new steelfuel line all the way and replacing all the fuel lines as i am planning on putting in a new larger tank. i was also told by a master mechanic at work that there is a check valve on the back of the injector pump that might cause this problem also?? he was not positive though
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TAZ01
Pre-Power Stroke Diesel (7.3L IDI & 6.9L)
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Feb 16, 2013 09:19 AM
