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fuel system?

cybane's Avatar
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03-13-04, 08:07 AM   #1  
fuel system?

97 ford f150 4.6 triton v8. 104k last tune up, september, autolite non platinum sparkplugs, set of federal mogul wires, and fleetguard air filter and fleetguard fuel filter, frame rail mounted driverside. About a week ago I borrowed my truck to family members, with a full tank of gas from phillips66 88 octane, medium grade as owners manual suggests. While family had truck, it started missing and running real ruff. Check engine light came on, took truck over to local AutoZone and their diagnostic tool said misfire on cyl's 4 and 5. suggested I replace both the spark plug coils. they are the same left and right, so I bought one and tried on both sides and no change, better or worse either side. When I shut truck off after I returned to home from AutoZone, there is a Very strong smell of fuel, both in cab and under hood. seems like after truck warms up, it doesn't idle as ruff but stilll misses. Any ideas? My next idea is to check fuel pressure on fuel rail with port on passenger side rail, but I dont have tester. Any suggestion welcome as to what to check next.

Thank you

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davo's Avatar

Join Date: Apr 2002
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03-13-04, 09:20 AM   #2  
If you smell fuel you need to find the leak now before driving it again.I would look for a leak at the fuel rail or injectors first since you can smell it in the cab.Maybe #4 and #5 injectors are leaking externally.Look closely so you don't get a fire going under the hood.After that check from the engine back to the tank or tanks.

mike from nj's Avatar
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03-13-04, 09:33 AM   #3  
mike from nj
well, at the least you have a spare ignition coil now, in case one ever does go bad.

what you, (or i regularly ) do is switch coils or wires around and see if the misfire moves while watching the cylinders on an 'active misfire' screen, provided that scan tool has that capability. it might take some time to reset a misfire 'code' to see if it moved. also, erasing codes sometimes erases important 'learned' information that is used by the computer to sense a misfire.

don't be surprised if one or two of those new wires are bad, especially if one is too close to the exhaust manifold.

i would have a fire extinguisher in one hand, and a strong flashlight in the other and find that fuel smell first. it might be the cause of both your problems. i wouldn't leave it running either, i would cycle the key to build up pressure or jump the fuel pump relay and find the leak that way. ( a guy in my shop needed an extinguisher yesterday, because he got too anxious with spraying parts cleaner and got near the distributor cap)

let us know

cybane's Avatar
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03-14-04, 06:24 PM   #4  
hi guys, thanks for your posts.
this morning I was able to locate the problem.
I have antifreeze leaking into cyl 5 from the intake manifold.
I pulled the wire form cyl 5, smelled coolant, checked, and about a third of the hole had coolant around the plug, so I took my air nozzle and sprayed the coolant out, checked the plug and it was dry. But i could see where the manifold had been leaking. replaced the plug and wire and the truck runs great. I guess the smell of fuel was from what was unburned in that cylinder? I looked and looked but never could find a leak.
Looks like quite a project to replace the manifold gasket, anyone ever done that, or know how hard it is or what the labor rate is?

Desi501's Avatar

Join Date: Oct 2003
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03-15-04, 03:46 AM   #5  
Do you have a plastic manifold? They are not that hard to change but there is a known problem with those plastic manifolds cracking. Pressure test it be be absolutely sure of the leak's location before taking it apart.

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