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Truck sputters at higher speeds

surewhynot

Rep whores make me sick
13,843
821
Florida
My work truck.
97 F250 (old body style) 5.8, 5 speed.

Coming back from a 140 mile trek earlier today, I started having a problem with my truck. I was running along about 80 and it started sputtering like it was shutting off, or running out of gas. I backed down to 70 and it straightened up for about a mile, then did it again. I slowed down even further, finally getting to between 55 and 60 before it would run without sputtering out.

I continued on at that speed to get it home. Other than the higher speed sputtering, I did notice that when accelerating, it doesn't really have any response past half throttle.

I pulled codes (weird, this truck has the old style connector, OBD I?)

KOEO test gave me a 33. (EGR valve not opening or not seated)

Engine running gave me a 538 (insufficient RPM change during dynamic response test)


Before I pulled the codes, I was thinking that maybe the fuel filter needed changed, so I was going to try that. Now that I see it has thrown codes, where do you think I should start? Any input?
 

smokey

Hitech hillbilly
Staff member
538 could be user error if you did not rev engine at the proper time.
egr could be sticking, apply a little vaccum and see if it is moving freely.
sounds like a fuel issue plugged filter or low fuel pump volume.
 

surewhynot

Rep whores make me sick
13,843
821
Florida
I was leaning towards a fuel issue. When I bought the truck, neither fuel pump was working, due to the truck being parked for too long, and the gas going bad. I only fixed the rear tank, I've been running on it. I can't remember if I ever changed the filter when I changed the pump. I know I should have, but I can't recall doing so.
 

blacksnapon

Moderator
Staff member
My work truck.
97 F250 (old body style) 5.8, 5 speed.

Coming back from a 140 mile trek earlier today, I started having a problem with my truck. I was running along about 80 and it started sputtering like it was shutting off, or running out of gas. I backed down to 70 and it straightened up for about a mile, then did it again. I slowed down even further, finally getting to between 55 and 60 before it would run without sputtering out.

I continued on at that speed to get it home. Other than the higher speed sputtering, I did notice that when accelerating, it doesn't really have any response past half throttle.

I pulled codes (weird, this truck has the old style connector, OBD I?)

KOEO test gave me a 33. (EGR valve not opening or not seated)

Engine running gave me a 538 (insufficient RPM change during dynamic response test)


Before I pulled the codes, I was thinking that maybe the fuel filter needed changed, so I was going to try that. Now that I see it has thrown codes, where do you think I should start? Any input?
They are right with the 538 (not revving the engine when requested) The older OBD systems can set strange codes, such as the 33. It may not have had the vacuum signal during the test, which would point you to a vacuum leak, pcm problem, egr valve, etc. It may have even been a problem unrelated to your current problem. I think I'd begin with the old standby, ignition problem. Once that is eliminated as a possibility, then look at map, egr, vacuum (power brake booster comes to mind), and vacuum lines. I'll look at some manuals just in case.
 

surewhynot

Rep whores make me sick
13,843
821
Florida
I guess now YOU should be the one calling ME for proper cleaning of an EGR :rofl:

I almost called you to find out why the test port isn't under the dash where it should be. I figured the truck being an early 97 would be OBD II. Guess not.
 

surewhynot

Rep whores make me sick
13,843
821
Florida
The 33 may have been a cheap beer induced mistake on my part. I'll do it again in the morning and check out all the suggestions. With the amount of varnish that was in the fuel tank when I changed the pump, if my dumb azz didn't change the filter, I could see it being plugged and it being a fuel problem. I just did a complete ignition tune up about 2000 miles ago, but that doesn't mean something didn't go bad. I'll rule that out in the morning too.
 

A_G

wuh?
3,188
74
Tulsa, Ok
Got the same issue as you do, If you end up changing the filter before i do let me know.

Mines so bad now, that below a half tank it run alright but not he best, a quarter or lower and its a damn dog
 

surewhynot

Rep whores make me sick
13,843
821
Florida
That's what mine shows, but I think it's unrelated to this problem. It's something I'm definitely gonna look into though.
 

surewhynot

Rep whores make me sick
13,843
821
Florida
The fuel filter was definitely in need of some attention. At idle, I'm supposed to have 30-45 psi at the rail. I was getting 30. I changed the filter and it jumped up to 40. I drove it around a bit and it seems to have solved the problem. Only time will tell, lol.

I cleaned the egr and cleared the codes. I'll pull codes again in a few days and see if any come back. Thanks for the help guys.
 

surewhynot

Rep whores make me sick
13,843
821
Florida
Same problems again today. Took it to a mechanic and his scanner showed the tps to be out of range. replaced it and still no luck. List of what I've dome so far-

Tune up- plugs , wires, cap, rotor
fuel filter
tps
cleaned egr
checked for vacuum leaks


Still no luck. Anymore ideas guys?
 

john112deere

caffeine junkie
Staff member
10,807
405
central Vermont
What was the old fuel filter plugged with?

You said it seemed to run better immediately after replacing the filter, but then it was bad again.

I'm wondering if maybe you got a bunch of crap in your tank and it's plugged the new filter, too... [confused]
 

surewhynot

Rep whores make me sick
13,843
821
Florida
Yes I did Chris. No change.


Ian, I checked the fuel pressure at the rail again tonight and it's still reading fine, so I'm assuming the filter isn't plugged. Also, I forgot to mention-

There is a new development. The truck is having this problem most of the time now. But, I can shut it off, re start it immediately and it will run fine for a few miles. This is why I believe it's electrical.
 

surewhynot

Rep whores make me sick
13,843
821
Florida
Wrong truck Aaron. This one is stock, efi. My work truck. 97 F250, 5.8, 5 speed.

If it was a carb and standard ignition, it would be fixed right now. :D
Everybody says efi is superior, you can just pull codes and it will tell you what is wrong. BS. There are no codes. Give me a carb any day.
 

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