Nuttymopar

I have noticed that my truck is becoming more and more like an 18- wheeler. When I slow down to a stop, the truck will start to shake or bounce. It is usually like the last 5 - 10 feet before stopping. Then it idles just fine. I go to leave and sure enough, the first 5 - 15 feet, it starts bouncing and shaking again. Now, if I place tranny in Neutral and slow down to a stop, either by coasting or braking, no shake or bounce. But once I go to take off, shake and bounce. I'm thinking it is more Fuel related and not tranny or shocks since being in neutral doesn't shake it and if I give it a good amount of throttle, it doesn't happen and truck zooms right off. Only at very low rpm when stopping or starting off. I do not have a Fuel Pressure Gauge so not sure what that is. I changed fuel filter and it looked clean. Pump is turned up but not fully and Timing is advanced. It has been happening for awhile (just getting tired of it now) so I don't think it is because it is starting to get cold out. Any thoughts and Ideas on what to look for. I can also hear the exhaust and it sounds like it is cutting in and out like it isn't getting fuel. I have NOT checked my fuel sending unit, fuel lines to see if blocked (truck runs great except stopping or taking off). Does the Fuel Pre Heater ever get clogged or have problems (heater above fuel filter). Easy to take off and service if so? Boy, truck bounces upon take off where it looks like it is up and down about 1 - 2 inches like on a pogo stick. Then it smooths right out if I start giving it throttle. I chould get a picture with sound from this with my Vid Cam if need be if that would help. Thanks.

Alec

I don't fully understand why you think it is fuel related. Seems more like bad motor mounts or slop in the drive-line (u-joints, slip yoke, or back-lash in the rear axle). When these things are under no load (neutral), no problem, and when they are under full load (harder acceleration) no problem -- so it seems like there is only a problem when play in the drivetrain can have an effect.

But -- I don't know . . . just making some guesses.

DJ

Only thing I can think of is that you have a manual trans and are forgetting to put the clutch in . Do you have a torque converter clutch and if so does it work ok. I'm voting on a trans problem here.

Nuttymopar

I haven't checked my motor mounts though when I replaced my motor this past Feburary, they were fine. I do have some rear end slop (clunks when putting in forward or reverse) but that has been like that for a couple of years now. I just can't kill it to replace it.LOL. Only when I give it slight throttle as I take off that it stops bouncing. If I just take off while in traffic like normal, it bounces. If I wait a couple of seconds till the traffic is in front of me by 20 feet or so, then I give it more throttle but not half a throttle or so, it won't do it. I will check to see when I replaced my rear driveshaft u-joints. Usually a yearly thing and I replace all 3 when I do. I don't think it was long ago but will check my books. Thanks.

Nuttymopar

is that what that 3rd pedal on the left is for....

I have a DTT 91 % tranny and they serviced it about 20,000 miles ago. Even then, scott (MassDiesel) noticed that bounce (not as bad then) and check the tranny and said it wasn't that. It is almost like it just wants to keep going and at that last moment before I stop, it stops bouncing. I think I will call Scott again and see what he may think.

Redleg

Sounds like the bearings are wore. They wobble when the breaks are applied, then wobble until they balance again when you accelerate. Mine is doing the same, and I'm sure it's the bearings, checking Sunday. I had the hubs apart for brakes last year and they were worn, but smooth. I had to re-use them, but expected to replace them.

Nuttymopar

My brother watch from outside the truck with a spot light and noticed that when the whole truck bounces, the axles and frame don't move at all but the body is what looks like it is bouncing off the frame, so I was looked underneath the truck and noticed that the 2 front Cab corner body mounts had some good rusty holes in them. I think I am going to get some steel and weld them in place to hold them together. The body mounts to the frame seem tight though dry cracked and worn in some spots but I didn't see them loose at all. I tried going in Reverse slowly and it doesn't bounce at all so maybe it isn't the motor fuel but body related or suspension somehow. I plan on changing out pass. lower king pin this weekend to tighten up front up but since complete truck shakes and not just steering wheel, must be either springs or body mounts.

Thanks.

jughead

you say 3 u-joints this means 2 piece drive shaft. really sounds like the joints on the 2 shafts are not lined up

Nuttymopar

Well, did a couple of things this weekend and have different thoughts. I replaced the Pass. Lower King Pin bearing and upper King Pin bushing. Upper didn't need it but had one so why not since there. That helped a little in my steering department. Still bounces but did notice that since we got dumped on for snow (19" in my front yard, more in higher elevations,,, ;D) this past weekend, that when I have the plow on, it doesn't bounce nearly as much, like maybe once or twice during the day. So makes me think it is more suspension related as springs are orignals but do have some newer Poly Shackle bushings in. With 1000 lbs weight in the rear (granite blocks and cap) and my 810 1000 lbs plow, it would make sense that they are loaded up good so no bounce. But without the plow, it might bounce due to the weight off the front springs. I don't see me replacing soon as I would wait until spring time to see if replace springs $$$?? or buy complete new 4 " lift kit that might include new springs?

Helicopter Dan

Nuttymopar, I have a boss Vee blade on my 92 cc 4x4, I changed the front springs out with new factory ones, trying to imporve the ride hight and suspension, but the new springs never made a difference. I checked into alot of different things and the two I have come up with are timbrens for the front or kelderman air ride. I'm going to try the timbermans first just because of cost, but I have spent alot of time talking to the kelderman guy. I like what the kelderman has to offer and eventually when I can afford it I will go that way.

Redleg

I had intended to use poly bushings. The suspension place I took it to said they would do it if I want, but it would make the ride really harsh, and would void any warranty on the extra leafs I wanted to put on. Maybe with the stiffer bushings, it only takes a little bounce for the springs to hit the stoppers. Even after adding a leaf, I think I only have about 2" between mine.