1990 problem
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1990 problem
I have a 1990 F350 with a 7.3 and a banks turbo. It ran great until recently I think it ran some old biodiesel and it stalled a couple of times. I've changed the filter (wix) and installed a new mechanical lift pump and now it starts only with the pedal floored, before it would start without touching the pedal. It runs well in the higher rpm range but lacks power in the lower but idles fine. It will also stall if you let off the gas quickly. Does this sound like the injectors got dirty or clogged from bad fuel? Any possible ideas/remedies would be greatly appreciated. Thanks!
Post Fiend
Joined: Jan 2005
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Here is what I would do, if it was mine. Get another new fuel filter and a can of Diesel Kleen (or other good diesel injector cleaner). Fill the new filter with Diesel Kleen, add any left in the can to the fuel tank. Fit filter. Start engine and let it idle for 30secs and shut it off. Allow it to sit for a few hours, preferably over night, then start and take it for a drive. See if that helps.
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Thanks! That restored all the low end power that was missing but it still stalls when you let off the pedal too quickly and still needs the pedal floored to start. Do diesels have IACs? Should have mentioned I've worked on too many gassers but this is my first diesel.
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Fleet Mechanic
Joined: Jan 2011
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From: 8600 ft in Colo
No, there's no Idle Air Control. Diesels have the intake wide open all the time. There's no throttle butterfly. Throttle is handled entirely by the injection pump.
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Update
The low end power is restored, it will just about start without flooring the accelerator now, and it will idle all day long but as soon as I get it on the road it will surge a couple times and stall. Takes it a couple of turns to fire back up and it will run another minute or so and same thing. A friend told me to put a good dose of diesel kleen in the tank and get it out on the highway so it can clean everything out, I don't see any fuel leaks around the lines anywhere.
Logistics Pro
Joined: Sep 2007
Posts: 3,737
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From: Western Mass
Sounds like a fuel issue. Either the filter is clogged, or something is blocking the fuel pickup in the tank. Biodiesel is a really good solvent and will clean all sorts of crap out of a fuel system which will then block up the filter. From what I've read, it may take a few filters to clean all the debris out of the system.
Idling doesn't take much fuel, driving around takes more. A blocked (or partially blocked) filter might let enough fuel get through to start the truck and idle, but not enough to drive around. Try the fuel pump test, there is a valve that looks like a tire valve on the filter, depress it and collect the fuel, I think its something like 1/3 of a pint in 10 seconds of cranking?? I would search first because I don't remember if that is the correct info, but it should give you an idea of fuel flow.
Idling doesn't take much fuel, driving around takes more. A blocked (or partially blocked) filter might let enough fuel get through to start the truck and idle, but not enough to drive around. Try the fuel pump test, there is a valve that looks like a tire valve on the filter, depress it and collect the fuel, I think its something like 1/3 of a pint in 10 seconds of cranking?? I would search first because I don't remember if that is the correct info, but it should give you an idea of fuel flow.
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Thanks for all the replies! I finally figured it out. The forward tank fuel gauge is incorrectly reading empty which led me to leave it on the rear tank. I am thinking the pump went out or is weak on the rear tank, it hardly sustains idle but the gauge reads correctly. I suppose at this point I need to determine if the pump is indeed bad and figure out wht the gauge isn't reading the forward tank. At least now it runs and drive very well once again I just have to keep the tank full for now. I checked Advance auto's website for a pump but there is not one listed, anyone by chance know if they are available aftermarket? Or is this a whole new thread? Thanks again everyone!
Logistics Pro
Joined: Sep 2007
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From: Western Mass
There is no pump in the tank.
The feed pump is on engine block, it sucks the fuel from either tank (depending on the switch) and pushes it through the filter to the injection pump.
Sounds like the fuel pickup, or the lines, are clogged on the rear tank.
The feed pump is on engine block, it sucks the fuel from either tank (depending on the switch) and pushes it through the filter to the injection pump.
Sounds like the fuel pickup, or the lines, are clogged on the rear tank.
Lead Driver
Joined: Dec 2006
Posts: 6,496
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From: So. Jersey
X2 and/or the selector switch is faulty and is not fully switching over to the rear tank which results in sucking air from the empty front tank. Also there could be an air leak somewhere between the selector valve and tank pick-up.