99 F150 Hesitation...

Hi - Have a '99 F150 Lariat, smaller Triton engine (4.8L) with 100K (just turned last week), owned since new and never really had any issues and love the truck. However, about 3 weeks ago a minor hesitation developed when you give it gas (under load). Idols fine but hesitates when going up a hill, accelerating, or step on it at highway speeds. (You can cruise at 65 without the hesitation, but if you give it gas it'll start). No SES light, and wires, plugs and fuel filter are only about 15K old.

Now I did have a problem similar to this once before early last year, (15k ago) that started with a SES light which was traced to a O2 sensor. I replaced that but no effect, so I changed plugs - again nothing until I changed the wires and that fixed it. The wires can't have gone bad again. (In fact, on my Brother-in-laws's suggestion, I replaced them with original Ford wires at $100 for the set, so they aren't some cheap after market brand) Any other suggestions on where to look? Could it be coil/electircal related again? Anyone know if it's a common problem for the coil packs to go? Little short on cash so I can't afford to throw too much money at it, so any help is appriciated!

Thanks,

Scott

Reply to
IYM
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First thing you want to do is get rid of that 4.8L engine, mostly because Ford never made one. Lets go with a 4.6L. There, it's probably running better all ready. If not check the fuel pressure. There's a service port on the fuel rail. Looks just like the end of a valve stem on your tire. Now all you need to do is get a gauge with a hose long enough and the proper end on it to screw on the service port. And then drive the truck with a friend and see what the pressure does when it hesitates. normal pressure is 30-45 psi and it should not drop more than 5psi after engine is off.

Reply to
monkeyboy

I gave it an extra .2L as 100K birthday present last week.. (heh) ;) Sorry - a little typo with that...

Thanks for the response - I'll give it a shot or have it checked....Thanks.

Scott

Reply to
IYM

I would start with a freebie and clean the MAF. There are instructions with pics several places on the web. Just run a google search for clean Ford MAF.

This may be a good place to start:

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Lugnut

Reply to
lugnut

Thanks!

I'll give that a shot first this weekend before I start checking the fuel pressure. Reading the info in that link you provided seems, it seems to make a lot of sense (plus it's cheap if that's the problem) If it is the prob, with the money I save I can afford to buy you an adult beverage of your choice!! ;)

Scott

Reply to
IYM

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