Hit a deer, now engine is running lean

zach1990 · January 23, 2014

I'll have to get my hands on a pressure gauge but ill definitely give it a look. The fuel filter is about a year old but as far as I know the truck still has the original pump in it.

bossier62guy · January 23, 2014

319K miles on an original pump....definitely check the pressure.

txab · January 23, 2014

319K miles on an original pump....definitely check the pressure.

+1

Also your codes have nothing to do with your downstream or post cat sensors

zach1990 · January 23, 2014

What exactly are they related to then? My scanner just listed them as "general - engine to lean (bank 1/2)"

bossier62guy · January 23, 2014

Basically your fuel mixture is too lean...meaning either you aren't getting enough fuel or you're getting too much air.

zach1990 · January 23, 2014

Ok thanks. Ill get a pressure test done asap

Doug_Scott · January 23, 2014

When you say the engine runs rough when cold, but runs smooth when warmed up, is this idle quality you are talking about? And once you pull away engine smooths out and runs fine? Next set of lights, rough idle is back, and by 5th set of lights, it is running good.

I can't see it being a fuel pump and only giving codes for lean bank. If pump is causing this, it should be spawning other codes. I think there is a code for injector duty-cycle. A bad pump should cause a long duty cycle for the injector. The two codes you posted are very generic basic codes. You will need to do a lot more testing and checking. Anyone ever check for ODBII for Dummies? I have found that series to be quite helpful for learning the basics first. Nothing worse than getting a manual that is written for experts.

zach1990 · January 23, 2014

The rough idle is during cold starts. I've got straight pipes and you can notice it kinda going in and out sort of like its loping. Does it till it warms up to running temp than goes away.

zach1990 · January 23, 2014

I've watched the rpms while its doing it and it fluctuates only 200-300 each time

Dnt · January 25, 2014

99% chance here that you are dealing with a vacuum leak. Those are the most common codes for vacuum leaks. Have a smoke test done on your intake. You will probably find a split line somewhere or a bad gasket.... Might be a bad gasket since you mentioned that it actually runs better as it warms up, the surfaces tend to expand with heat and form a better seal sometimes. Good Luck

zach1990 · January 29, 2014

Well decided to start at the fuel filter even though it's not very old and low and behold its all clogged up. Replaced it, changed the oil, and put in a new battery (unrelated issue) and now the old thing is purring fine. Hopefully it's fixed. Sure feels like it

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Doug_Scott · January 30, 2014

Well decided to start at the fuel filter even though it's not very old and low and behold its all clogged up. Replaced it, changed the oil, and put in a new battery (unrelated issue) and now the old thing is purring fine. Hopefully it's fixed. Sure feels like it Sent from my LG-D800 using Tapatalk

If you want to take a stretch at tying the rough running with the deer incident, maybe the jarring the truck took on impact, disturbed a layer of crap in the bottom the fuel tank, that got sucked up in the 15 to 20 seconds the truck ran after crap got stired up and fuel filter did its job.

bossier62guy · January 30, 2014

What would concern me is, "why is a relatively new fuel filter clogged?"....hopefully it was a fluke and not an indicator of problems to come.

BTW, I don't buy the logic from the above post....lol.

Doug_Scott · January 30, 2014

What would concern me is, "why is a relatively new fuel filter clogged?"....hopefully it was a fluke and not an indicator of problems to come.

BTW, I don't buy the logic from the above post....lol.

Really? Think about it, you drive your truck for x number of years, and x number of miles. Over that time if you get your fuel from mostly the same station and they have a dirty underground tank, you may get dirt in the fuel. It sinks to the bottom of the tank where it gets to sit for the vast majority of the day. You vehicle is parked more than driven, so the fuel has lots of static time for contaminents to sink to bottom of tank. After a while it ends up like one of those instant hot chocolate. A layer of sludge on the bottom. One day you are driving along, not a care in the world, then bambi decides she really misses her mother so she ends it all by stepping into traffic. A vehicle something as large as a deer will feel it (not as much as bambi, but it still jars the truck) and the sudden shock to the vehicle will cause a violent movement of fuel in the tank(unless it is full) and that mini tidal wave stirs up the fuel in the tank, and the crap in the bottom. Truck is still running, so fuel pump pulls in the now cloudy fuel, and off the fuel filter it goes.

Not sure why you don't understand the logic of it. Before you offer that the sock on the fuel pickup will catch the stuff, if it did, why would you need a fuel filter? And if the gas station does not pump dirty fuel, why do we have fuel filters? Obviously dirt gets into the fuel tank.

For some reason this reminds me of when I worked in a Firestone Auto Garage. We used Kralinator filters. A week did not go by without someone complaining that they just changed the air filter x number of miles ago, they must be crap filters if they plug up so soon.

zach1990 · January 30, 2014

I don't understand it either but I've got 320k miles and know my truck pretty well. She's running like she's supposed to. Let it idle for half an hour and took a 12 mile drive and no codes. I'll report back if it changes. Thanks for all the help guys!

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