The 2011 F-150 I acquired in June (5.0l V8) has done well for me on several trips to Canada, but I was sadly disappointed when I towed a camper this past weekend. This cannot be right.

The camper is 24' and weighs about 4800 lbs. Weak take off pulling the camper on level ground, and nearly incapable of maintaining 45mph on simple grades. (I'm talking about long little interstate inclines, like 1%-2% grade max.)

I've never owned an F-150, but my 2000 Expedition with a 4.6 could run circles around this truck.

That leads me to the question - what in the world could be wrong?? The truck seems to run fine without a load. In fact, if I stomp it at highway speeds it'll downshift and lunge forward like a Mustang! So this problem is clearly only when it's under load.

I did try to pull in both Tow/Haul configuration as well as a short distance in normal configuration. Tow/Haul seems to be working as expected with engine braking and no overdrive, but no material difference in the overall struggle.

Is it possible for the transmission to 'slip' horribly under load but seem to do just fine otherwise?

I monitored the trans fluid temp for the duration of the 30 minute tow and it never went past the halfway mark on the gauge.

Just looking for guidance how to troubleshoot, or generally where to begin looking to figure this out.

Truck has 114k and records show a transmission fluid drain and fill at 70k.

Thanks!

 

I pull an open car trailer that weighs approx 5000 lbs fully loaded with gear and stuff for racing. My 13 5.0 tows this and down the worst hills in New York without slowing down at all. I've heard guys at the track complain about enclosed trailers or campers struggling bad because of wind drag. I wonder if your truck has partially clogged cats or some other issue?

 

It sounds like you have a 3.31 rear axle, which doesn't help anything, does the pickup run well without a trailer?

 

3.31 axle here. Towed a loaded 16' enclosed tandem axle (approx 5500 lbs) a couple weekends ago 450 miles and while you could tell the trailer was there, I had no problems achieving and maintaining 70 mph. This is also with a 5.0 crew cab and tow/haul activated. Fuel mileage though, thats another story.....

 

Thanks for the comments please keep any ideas of what I can check coming.

I do have the 3.55 gears, and I *thought* the truck was fine without a load, but now I'm starting to wonder. It's running the same as the day I bought it in June, but it's possibly been a pig since day one. I guess I need to shop around and find another 5.0 to test drive as a reference.

Aside from the cats potentially causing a loss of power, anything else I should research?

 

Do you know how recently your plugs, and fuel filter have been changed? Changing those may makes a difference.

 

Fuel filter is a "lifetime" unit on these trucks. I put that in quotes as I'm sure there are some rare cases where and issue warrants replacement.

Per manual - plugs should be changed at 100k miles. Is there any record of that in the service records?

 

I wouldn't condemn the cats just yet. Plugs and boots would be my first thought.

 

If you want to check your cat function..drive the truck until it is up to operating temp. Park and immediately use a temp gun to measure the inlet pipe at the cat. Then measure the outlet pipe just after the cat. There should be a 50-100 degree temp increase on the back of the cat. This is the chemical reaction doing it's job. If its clogged, it's not doing its job.

 

Does the camper have it's own brakes that could be dragging?

On E85, these trucks are rated 375 HP/390 lbs/ft and shouldn't have any trouble at all with a 5,000 lb. load. Although, they do like to rev hard to make that power. These engines like to be on the top end of the RPM band where they can breathe like a race horse.

 

what gear and what rpm where you pulling to go up these hills?


how deep were you in the throttle?


did you try towing with the cruise on? may don't because the cruise will do what it can to keep speed causing downshifts ect, but it might give you a clue if the cruise can keep speed, but you can't with your foot.


I'm towing more than that with my 5.4 in the expedition and I can always maintain speed at 65mph. I might have to make it downshift to 2nd to do it, but it will pull the 4-5% hills around here at 65 if I want. you shouldn't have problem keeping speed with more horsepower and more gears than I have.


to answer your question about the transmission slipping under load -- no, that's not possible. if it were to slip like that it would only last a matter of seconds before the clutches are toast and you'd be done. a bad torque converter is a possibility, but not something internal.

 

EXCELLENT COMMENT about the trailer brakes. It's an old camper and I checked the brakes and found them "not working" but didn't consider they may be partially locked up. Easy enough to test.

I should be more clear than I have in the original post about the performance however - it's not something I'd expect to be plugs or filters. I'm talking about SEVERE underperformance. I had to run third gear at 4500rpms in tow/haul mode just to get up a small hill. So, I can't overemphasize how significant the issue is.

Thanks for the great idea - I've kinda got blinders on at the moment and would've never thought to check the trailer for significant resistance on the brakes. If I'm so lucky, the truck is fine and all I need to do is refurb the trailer brakes which they need anyway.

Will advise, thanks!

 

Well if that's all it is, that would be fantastic. Definitely look into it. I've also seen the parking brakes on the truck (which are drums inside a small hat in the rear rotor) get out of adjustment and drag. But since your truck runs great UNTIL you hook up the camper, my guess is the camper brakes could be the issue here.

 

Being that the trailer is older, also check the bearings. Great catch by WXboy, I wouldn't have immediately thought of there being a problem with the trailer either.

 

Of course none of us have seen the offending trailer or hill, but it almost sounds to me like you have unrealistic expectations.

What RPM would your 4.6L truck pull this same trailer and hill at?