Hi All, I need a bit of help. I have a 1999 F-250 SD V-10 6.8. 146,000 Miles.

While pulling a small horse trailer I noticed that I would seem to lose power (truck would buck lightly) when going up hill. A week or so later I noticed it again when I was empty going up a hill. A week or so later I was camping with my family and anytime I would head uphill, or accelerate it would buck pretty bad, I kicked out of overdrive and the bucks became less intense, but the frequency continued.

I finally stopped at a small town and picked up a fuel filter, sure enough, it was full of sand, I could barely blow through it. I replaced it and went on my way, it seemed to have a bit of a problem still so I assumed it was sucking air out of the filter. But it's been 3 weeks now...

I just got back in from pulling off the filter again and the fuel came out clean as can be.

My next guess would be fuel pump, but most people I talk to say that the pump would only last a few days then would die entirely, sounds like it just goes when it's time...

What else would I be looking at that would cause me to loose power, almost like a misfire, when I'm under a load? It's not as bad now, but I can pick the hill on the way home from work and have it buck 4 out of 5 times... Something electrical?

Any help appreciated... Thanks!

 

Misses under load are very common in these trucks from weak COP's (coil over plug) or bad/contaminated boots, also wore out plugs. Often with no check engine light or codes. If you're lucky you can pull codes or possibly pending codes to find the problem cylinder but when my '03 COP's started going weak it was no help for me. I did the buy one and swap it around thing two or three times over a fairly short period of time until I just bought all the rest to be done with it.

Super common problem, coming up two, three times a day it seems.

 

Squisher, Thanks for the input. I look on Amazon for the plugs and sadly, they all come in packs of 8... I assume that if I buy the cheapest, I'll still have this problem. Is there a brand known for quality without breaking the bank?

Thanks

 

Some here say only use oem. I won't argue with them.

Are you talking about spark plugs? The boots? Or the COP's?

I'm no good with links Google 'v10 spark plug replacement'. You'll find the threads here that way that you need.

 

My first thought is, where did the sand in the filter come from? The logical answer is that it was pumped into it from the gas tank through the fuel pump unless someone intentionally placed sand into your filter and reinstalled it. That would mean the pre-pump filter (sock) has failed and should be replaced.
If this was my truck that had a fuel filter full of sand and I wanted to plan to not have it die on me on the side of the road, I would drop the tank, clean the tank, replace fuel pump assembly with all new parts, & clean out all the fuel lines from the injectors to the tank. Also fix or replace whatever is leaking that allowed sand to get in there. You might also want to consider a locking gas cap.
Checking the fuel pressure at the fuel rail would tell you if that is the problem or not, if you can replicate the problem with the fuel pressure gauge hooked up.

If you don't know when the spark plugs were replaced last, you should go ahead and change them. If you do know, you should have included that info in your original post.

Use Motorcraft platinum plugs. Anything fancier and you are wasting your money, anything cheaper and you will be changing them again sooner than you want.

Look on Rock Auto dot com site. You can buy the coils & spark plugs individually. Get Denso coils, they are half price of Motorcraft and are literally the exact same part. If you aren't sure if you have a bad coil or not, you don't really need to replace all of them just get a couple to have as spares.
But what should be replaced at every spark plug change is the coil boots, the rubber part between the coil and the spark plug. The rubber gets bell shaped at the plug end and it can crack and leak or short to ground as it ages. New boots include the springs inside them.

 

I will add when my coil over plugs started weakening(possibly bad boots) I chased fuel supply at first too. I was convinced it was fuel until I tapped in a mechanical fuel pressure gauge and drove around a bit watching it. Not hard to do with a relatively inexpensive 'kit' I got through Canadian tire up here.

 

Your symptoms are of a very common low grade misfire.

Use your scan tool in Mode $06 to look at individual cylinder misfire data when it's misbehaving.

 

I appreciate all of the input. I live remotely in Oregon, so I order most everything on-line. I hope to have everything Monday to swap out.

If this issue is solved by such a cheap tune-up, I'll be ecstatic... I'll report back next week.

Thanks

 

What all did you order? Good luck with it! Search around for some of the plug change threads if you haven't already so you'll know what you're in for.

 

I ordered a boot/coil/spring set-up, all 10. And 10 spark plugs. I have heard huge issues with this motor throwing spark-plugs, so I'm looking up torque specs. 168 in/lb.

I found a good plug change thread, I sometimes miss my old 68 ford... I could sit on the inner fender while I worked...

How serious is the concern of throwing plugs? Does it really happen all that much? Or does somebody have to really screw up for it to happen?

 

The spark plugs eject because they aren't tight enough. You should up the torque to 25-30 lbs. ft.

 

From 14 lbs. ft to 25-30? In these aluminum heads, what is the danger of stripping them?

 

If I remember correctly in my '03 and it has the thin threads I went 25lbs, might have been 22?. None of my plugs stripped and nearly two years later none of them have spit out. I remember someone on here saying that the stripping of the threads isn't likely, that the plug would break first. I don't know about that, and I never tried it obviously.

Pay close attention to the cleaning out of the plug holes. I blew mine out and then taped a small line onto my shop vac and sucked them out. I also used a inspection mirror to look into the holes as best I could before removing the plugs. Also, and I feel it's an important step. After getting the plug holes as cleaned out as possible I 'cracked' each plug loose but didn't fully remove them, then I blew and sucked each hole out again to ensure nothing would drop down into the cylinder. Clean, clean, clean is the name of the game. I found that no matter how well I cleaned the hole ahead of time after breaking the plug loose there was a bunch of dirt and even small rocks in one cylinder that loosened up from being seated down in tight against the base of the plug. Hope that helps a bit.

 

Also I compression tested my motor at this point as all the plugs were out and it's easy to do. Last thing I wanted to do was all of this maintenance and if it didn't run right be wondering about the health of the motor.

 

[QUOTE=Squisher;16346392]If I remember correctly in my '03 and it has the thin threads I went 25lbs, might have been 22?. None of my plugs stripped and nearly two years later none of them have spit out. I remember someone on here saying that the stripping of the threads isn't likely, that the plug would break first. I don't know about that, and I never tried it obviously.
QUOTE]

I torqued mine at 25lb-ft and have had no problem. There is a video somewhere that shows plugs torqued until the break with no damage to the threads.