bigbobr

Own a 2007 F-150 5.4 ltr with 75, 000 miles. Truck runs great when not towing. When towing my small 18 ft. boat the truck runs ok til I give it gas then it starts to jerk like having the hic-cups.I don't know were to begin. Is it the tranny, engine, electrical or fuel system. Any suggestion would be appreciated.

tomb1269

Does it buck from a stand still or only while moving down the road? Is the bucking worse when the road surface is rougher, like particularly when your on a concrete hiway and you hit the expansion joints? It bucks when you apply the brakes light to modrate and then step back on the gas (like when your in slow traffic or stop and go type traffic)? If so what you are most likely feeling is the aplication of the trailers tongue brake. If not, check you rear suspension, as the shackles on the leaf springs are know to rust out and fail. And trust me you may not even notice if one has had a partial failure untill you look.

bigbobr

The jerking is not from expansion joints in road or rough roadways, nor is it from a trailor tounge brake as my trailer isn't brake equiped and the leaf springs are perfect. The problem is while cruising and I step on the gas to accelerate or begin to go up a grade the truck would shutter and shake til I ease off the gas. Been told tranny, electrical, fuel could be the problem. I don't know which to check out first.

tomb1269

Our trucks drive by wire also controls a fuel demand module that controls fuel flow/pressure based on truck speed. The module is above the spare tire and the backside auminum case corrodes and it causes all sorts of issues. Check to see how much corrosion is on your.............

SkiSmuggs

Spark plugs? Mine were shot at 40k.

KingRancher05

My 05 5.4 did this but only when I accelerated using cruise control changed plugs and now it's golden

stufarmer

I interpret the OP's question as the Loose/Play being felt between the Hitch and the Receiver when the trailer is locked onto the Hitches Ball. I use a Brophy Anti-Rattle stabilizer bracket available on Etrailer. It's under Brophy Hitch Accessories #BHSB. It secures the Receiver and Hitch assembly together therefor eliminating feeling and sounds I believe the OP is describing.

papa tiger

First inspect the fuel pump control module like above then spark plugs etc. Also if fuel psi is low U can have damage inside the tank at the fuel pump. This happens a lot.

bigbobr

Well, first I want to thank everyone for their imput. Problem solved, it was bad plugs. Changed them all and cleaned the throttle body and now my truck runs like new. Towed my boat from Miami to Marathon in the florida keys and back without one bit of bucking. Thanks again

bigbobr

Yes, the plugs turned out to be the problem. Truck tows smoothly. No more bucking and jerking. Thanks again.