So I've searched through the forum before posting and I can't seem to find the exact issue that I'm having. I have a 1990 2.9l 5 speed manual Ranger and just today I started getting a vibration that reverberates through my cab at roughly 40+ MPH. I know it's not an out of balance wheel or something like that since the vibration goes away as soon as I let off of the gas but comes back immediately when I push back on the has pedal. Seeing as this is so, I thought to myself maybe one of my fuel injectors isn't working properly under load. I pulled out my spark plugs and noticed that too of them appeared that they were running hotter than the rest, like maybe fuel supply to those two cylinders was being limited. I'm trying to upload a video of the spark plugs to this thread. If that doesn't work I will upload to YouTube and post the video below.

 

Here is the video of the spark plugs:

 

How often do you perform preventative maintenance? Such as, oil changes, filter changes etc.?

 

Oil and filter twice a year (I dont put many miles on it) and other maintenance as things pop up. I've had it for about 7 years now and do pretty well at keeping on top of things with it. Have changed out quite a few parts over the years. It has 163k miles on it currently.

 

This may not have anything to do with it but my 4 cyl 2.5 had a similar issue. It ended up being a blown head gasket that leaked coolant into the cylinder. It took about 2 months of diagnosing and then it finally got worse and I could see it leaking with a borescope. So it started like yours but progressively got worse. My wifes 3.0 had head gasket issues but it was from over heating after a ruptured hose and different issues. No vibration form engine. Just something to think about and hopefully not your issue.

 

Have you used a fuel injector cleaner you add to the fuel tank? I use it at every oil change. Brought quite a few family vehicles back to life with it as well. I use Chevron Techron and Seafoam . I go a whole bottle to about a half tank of fuel for dirty injectors. You may consider new plug wires and plugs as well. Not expensive at Rockauto.com.

 

Yikes! I hope it's not a blown head gasket. I will keep an eye out for signs of that though. There hasn't been any indications in my oil that coolant has been mixing in but thanks for letting g me know something else to look out for.

I did a bottle of Seafoam in the gas tank about a month and a half ago and also did a bottle of the Seafoam spray that you spray directly into the throttle body. As far as gas goes I only use Chevron.

I did just replace my fuel pump and fuel filter just a month ago as the fuel pump quit working. With this latest vibration situation I was worried that maybe some old gunk got knocked loose somewhere in my fuel system and that was maybe causing the truck to misfire under load. So yesterday,, I checked fuel pressure at idle, while driving, and when the vibration occurs. Everything is fine there. So then I took out all of my fuel injectors and tested them with a voltometer, all of them are within spec. I tested them for spray pattern and they all appear fine as well.

I am now thinking, based on other internet research, that it may be a bad motor mount or a U Joint. I will be doinng some more digging around in the truck today.

Any other ideas from anyone?

 

Open hood
Start engine and look at the engine through the gap under the hood
Set Parking brake or have foot on the brake
Put in 1st(manual trans)
Slowly let clutch pedal up and watch engine lift a little on one side, should only move a little, then push down pedal fast, should be no "clunk" noise
Repeat but in Reverse
This tests both motor mounts

u-joint vibration should be strictly speed related, like out of balance tire
Find a downhill location and get up to speed then coast with trans in neutral and engine at idle to see if you still have the vibration, if so its drive shaft or tire related

Most places do not "load balance" tires, not really needed unless there is a problem, if a band separates inside a tire it will "spin balance" just fine, but it WILL cause a vibration when weight of vehicle is on it at certain speeds
"Load balance" is when they spin balance a tire with load applied by the machine
So don't discount a bad tire as the issue because they were "balanced"
Long shot but not a no shot, lol

 

Alright I found the source of the issue and have repaired it. So my Ranger is an extended cab and it has the two piece drive shaft with carrier bearing. Well I did I little more inspecting underneath and noticed that the rubber portion of the carrier bearing was all tore up. I took the drive shafts off to replace it and decided to do the u-joints while I was down there. Turns out that one of them was missing its needle bearings, so obviously an issue as well but you could not tell by jostling the drive shaft while it was attached that the u-joint was bad. I got all of that replaced and my truck drives smoother than it ever has. Thanks for everyone that took the time to reply and put their input in!

 

Good work

Thanks for the update and THE FIX

 

Ya I figured it was best to post what my actual issue was in case anyone comes on here later with the same issue. The more info we have the better. Thats why forums like this are such a valuable resource.

 

I have a 2007 FX4 Level 2, automatic. about 154,000 miles. I have a vibration problem at 50+mph that gets worse when I take my foot off the gas or just decelerate. Do you think my vehicle could have the same problem as the OP? I've read a bunch of threads and no one seems to have a vibration that is worse when you take your foot off the gas. It's still there if I shift to neutral, so there's that.

 

Sounds like U-Joints to me!

 

Thanks for sharing.