Ben W

I've had my '91 W250 for a few weeks, and now I'm preparing to go on my first trip with it. I will be hauling a 9' slide in camper and towing a 7000# trailer. After loading up and taking a test drive, it looks like this is going to be a slow trip if I don't do something. Full throttle on a flat road the truck will only do about 50 mph. I'm heading into the mountains, so I think the lack of power is going to be a problem.

I was planning on waiting until I had guages to do any pump tweaking, but now I'm wondering if I can do anything without the EGT becoming a concern.

wannadiesel

That sounds slower than normal. First thing to check is if pushing the accelerator to the floor actually gives full travel at the pump. Many trucks have worn linkage or a stretched throttle cable and will only give about 2/3 throttle travel. Adjust the linkage or bend the accelerator pedal arm to get full travel. It's also safe to pop the tamper cap off the high idle screw (the screw the throttle arm hits at full travel) and back the screw off more. Just make sure that the screw stops the linkage, not the insides of the pump. This gives you about 300 more RPM and a touch more power.

jiMMyCTD

my friends w350 91 as well, with teh 3spd auto, does this. and always has since day one of purchase back in 91 when his dad bought it.

floord will 55-60mph empty flat or up hill. throw 11,000 lbs at her and it goes 55 up grades. its just the way the motor works i guess.

but yes lil tweaks will help.

jiMMy

Ben W

Empty I can do 70 no problem. I have the 4spd auto. I'll check the linkage and adjust the high idle screw. Can I do anything else without worrying about the EGT, or should I wait until I have gauges?

wannadiesel

Other than making sure the air filter is clean and the tailpipe isn't crunched above the rear axle, there's nothing else safe without gauges. Anything you can do to add air is fine, adding fuel blindly is a big no-no.

apache

Might wanna replace the fuel filter. My 93 350 I put the fuel pin to full rich and had the star wheel bottomed out then later installed a pyro. Empty I could get 1100 up a 5% grade that was 3 or 4 miles long. Id be hesitant to do that with no pyro pullin the load your talkin about. I also have a 93 250 that I pull a 1500 lb camper towin a 3500 stock trailer and 2 horses. I have a trans guage in it and if its hot you might wanna be easy on the trans, we ran in O/D on flat ground , but when we hit grades we put o/d out. I think your 91 is non intercooled which might be a heat factor on EGTs. It seems your lackin power for some reason. My 93 had the pump done with a 15% HP increase and will do 100MPH and pull the mentioned load pretty easy and get 13mpg or so. You might want to consider making a under bed trans cooler set up like the factory unit that was once avaliable if you dont have one already.

Alec

Check the air filter, fuel filter and tailpipe first. Then check to make sure that flooring the pedal pulls the pump lever all the way.

If you don't find any problems there, undo the banjo on the AFC cover and take out the four screws that hold it on. If it pops up more than about 3/16", you need to adjust your star wheel -- the AFC is not letting your truck get full fuel. There was a service bulletin about the AFC being too stingy .

If it only pops up about that much, then mark the diaphram position and pull the afc eccentric out. Look into the bore and pull the accelerator lever open all the way. A little pin should pop out of the front of the bore. If it doesn't, try spraying some WD-40 or other gentle penetrating lube on it and cycling the accelerator until it does pop out. Lubricate the pin and the eccentric pin lightly with high-quality grease and put it all back together.

Turning the eccentric so that the pin rides on the deepest part will give you more power -- possibly enough to do damage without gauges. The further out this pin comes, the more fuel the pump will deliver . . .

Good luck!

Ben W

I replaced the air filter and fuel filter yesterday, I'll check the tailpipe, I've looked at it before and I don't remember seeing anything out of the ordinary. The truck is intercooled, so I guess it is a 91.5? I'll check the AFC out too.

TexasHardcore

With about 600lbs in the bed, and pulling a U-Haul car transport trailer with a 2,600lb car for 350 miles, my truck had NO problem doing 70-80mph, even up hill. Yes, it's not a serious load, but it's the most I've towed with this truck. Of course, the "hills" on I-35 between South Texas and Waco aren't all that steep. It was mainly sluggish in the lower gears, but on the highway my truck pulls like a freight train, with room to go. I never saw over 900-degrees even at full throttle and 26psi boost.

Get those gauges, tweak that pump, run a 4" exhaust and a BHAF...you shouldn't have any problem towing much of anything.

Rammer64

I'm getting the BOMB BUG. Went out tonight to try a few things.
I'm not rich so I had to try the cheap fixes. I turned the throttle stop back three turns. That little fix made one hell of a difference.
Truck would hardly max out @ 80mph. Now @ 82mph, I still have pedal and it pulls hard up to 89mph and then I had to back 'er down cuz my exit came up.
I also adjusted to take out the play in the heim joints on the throttle linkage. Another bit of difference.
I was gonna try playing around with the timing and advancing it a few degrees, but didn't have the tools here @ home to lossen the pump. I got them at work.
That will be another project for another night.

Starting to go STIR CRAZY at what the next bombing mission will be.

Ben W

I adjusted the linkage, gained about 1/8" of travel, hopefully that will help a bit. I didn't have time to check the pin in the AFC, I will look at that tomorrw.