surging, hesitation

[ulmapache]

Ok, '84 F250, 2WD, 6.9idi, T19... New front tank, sending unit, switch valve blown out with air... Everything copasetic during normal driving around town, or hiway...however, if I put my foot to the floor after getting into 4th (around 25mph or so)...after a bit, I will get some hesitation and surging...happens on either tank...goes away after a bit of normal driving at hiway speeds. Usually do not go all the way to the floor when accelerating... So...what's the consensus here...fuel lift pump, or IP...or both. Thinking on doing the lift pump first and see it the issue goes away. Less $$ too...IP is a spendy proposition...'specially on a fifteen hundred dollar "go to the dump" truck. Do not want to get stuck with a load of crap on the way to the dump however... Thx for the replies!!!

 

[Chief]

Have you run ATF through your system yet? Could be as simple as crud in your IP, lines, and/or injectors.

 

[ulmapache]

Oh yes...ATF, and Power-serve, and Lucas...fuel system is clean...even had my mechanic do an injector clean-out with some commercial grade cleaner..

 

[Greg85]

Oh yes...ATF, and Power-serve, and Lucas...fuel system is clean...even had my mechanic do an injector clean-out with some commercial grade cleaner..

I'm assuming the filter has been changed also, just asking.

 

[Robm45497]

4th gear at 25mph, your lugging it to much.

 

[Scotty4]

Toss some hotshots extreme in there and drive it like you stole it. Many had recommended that to me and it worked well. Now every so often I try to run each gear out getting on the highway.

 

[Greg85]

Toss some hotshots extreme in there and drive it like you stole it. Many had recommended that to me and it worked well. Now every so often I try to run each gear out getting on the highway.

 

[Greg85]

I just went thru a similar situation with my 92 SD. Occasional surging, sometimes low on power. Put a pressure guage on the filter head- no pressure. Changed the lift pump, back to 5 lbs. Starts better, runs smoother.

 

[ulmapache]

Doing a pump today...will post on results...