i have a 1986 f250 6.9 idi.i recently replaced the injectors,return lines,the injector pump.the truck was runing fine untill it started surging when u were not even laying into the throttle.my speed would increase 6 mph without laying into the throttle harder it harder.it will also act like its missing at idle. i replaced the lift pump and the issues getting worse

 

My guess would be your noting getting enough fuel. Is the new lift pump from napa?

 

if it was fuel delivery it would nearly die when you stepped on it, sounds like sucking air between lift pump and tank,

 

the lift pump is from advanced auto parts. the truck also does rappidly loose power when u are cruising down the high way.i believe the injector pump is bad.the truck died at work today,i have fuel to the filter but no fuel to the injectors

 

Cracking the injectors lines might help. You may still have some air intrusion on the return lines

 

rare but you might have some debris in fuel line to the ip verify that you have no obstruction's the iDi consumes about 9oz's of fuel per minute when cruising min fuel pressure is 1lb if the sprinkler head in tank has collapsed the lift pump could draw air some where before the lift pump,or tank selector. my van had a tiny leak a worn thru spot and it would suck air, I installed a air tex low pressure flow thru style fuel pump, 3-5lbs, just after the tank selector valve, when activated it leaked, I found the worn thru spot, and fixed it, now if needed I can prime fuel system with the flick of a switch

 

well the truck let me sit friday leaving work,and i finally got it home tonight.i was. getting fuel to my pump but no fuel at the injectors.i had to crack the injector lines and crank the truck till i got fuel then it started,but ran like crap.it would serge and die the whole way home.

 

You want my advice? Dont drive your truck to work tomorrow.....just a joke man

I would verify taht the Ip is getting fuel as was said before. Theres better people here than me that can verify if your IP is toast though. I just wanted to tell you that if you do decide you need an IP that i would recomend you go to a local Inj Pump and get yours rebuilt by someone with a good rep. I bought mine from pensacola with a year warranty....and i needed it. Sure they replaced it easy and quickly but it was still a PITA...luckily my truck is mostly off road so had no Tow bill and i wasnt away from home. Now i have a working pump and its been a year but i sure would feel better had i got the old one looked at by a shop i trusted. Afterward ive seen some bad stories in here about Pensecola IP. I dunno, but if a person has to get stranded and get a tow etc it sure would pay to spend that money on the IP...if it would be more and im not sure of that but if so it would be worth it.

 

Have you figured it out yet? My truck is doing the same thing! I just picked her up from the shop today. they replaced the lift pump and thought that was the issue. Took her back to the shop and took the mechanic for a ride. He says he is "pretty sure" it is the IP.

"Pretty Sure" is not the answer I am looking for after what I spent at the shop today. So, The Gear head at the parts store recommended a local Diesel shop, and when I spoke with that shop today, the "classics" specialist said he thought it might have something to do with my timing? I'm gonna read up on the pumps and timing for a diesel ( this is my first diesel) But if you found out what it is, I would love to know BEFORE I go to the shop. I really hope this place is good. It's hard to find a trustworthy shop out here, and I will be driving about 50 miles for the diagnosis next week.

 

Surging is usually caused by air intrusion. Don't throw money at the pump. I have the same issue except that I have an electric pump and a rebuilt IP so it keeps running because the pump is forcing fuel to the IP. I know I'm drawing air but I can live with it till spring until it gets warm enough for me to crawl around looking for it. Is idoing it with both tanks or only on one particular tank?

 

Okay, this is just a thought, and one I won't be able to prove/disprove until I can get her in the shop. BUT, I replaced the water pump back in May. I was very unhappy at the time because I could not find an OEM water pump and had to go with an aftermarket. It was built a bit different and had a warning about the bolt length and damage to the IP occurring. I made sure that the bolt was the length specified, but will have it checked when it is in for diagnosis. I HATE not having OEM parts available for this very reason. When something goes wrong later, you sit and wonder.

 

Okay, never mind. I went through my records, and the truck was surging before I put the water pump on. So, they shouldn't be connected. I will have it checked anyway.

 

If you had put the longer bolt where it shouldn't go you would have known about it as soon as you turned it over!

 

My truck used to surge and I fixed it by replacing the check valve on the fuel filter mount (I think this was the problem) and the fuel selector valve (was drawing fuel from the front tank but returning to the rear and my fuel gauges didn't work so I didn't know I wasn't getting fuel).

If your having trouble with air intrusion or suspect you are parking with the front of your truck downhill should help.

 

That is good to know Scratcher. Thank you. I am eating lunch right now, and then I am going out to work on the truck. I went out to start her earlier, and she wouldn't start. I am so disgusted. I paid $300 to that shop because I needed the problem diagnosed and fixed. If all they were going to do was throw parts at her- I coulda done that. I thought I would save time and inconvience ( considering I don't have a shop and it is below freezing out here) by having a shop diagnose and repair the issue. the mechanic had said something about her stalling on him and when he pulled the fuel filter- it had air in it. He said the lift pump was leaking and that was what caused the air intrusion. But, the truck surged when I picked her up. I took him out, and his next reply was that he was "pretty sure" it was my IP! WTH! Diagnose the damn thing, Don't guess. I could do that.