Hey guys, sweet board here, I have been lurking for a while.
My truck, 88 F150, C6, 351, I have been having a problem with the truck surging up and down, mostly at lower rpms, near idle, and normally after it is up to operating temperature. I have cleaned the IAC with no luck, could this be completely shot? and is there a way to check it?
I have replaced fuel filter, plugs, wires, cap, rotor in search for a solution. I am also getting 7 mpg, combination highway/city driving, I thought whatever is wrong may also cause bad mpg, I am expecting to get maybe 10 mpg, am I far off? It kind of sounds like the fuel pump is actually surging as well, I am planning on doing both tanks (they both leak a little) and pumps.

Thanks alot, sweet board!
John

 

is this carbed or efi? if it is efi . get a code reader and check the codes .could be several issues . we have gone over a few of them in other posts here and in ENGINES sections .

 

It is efi, I will have to get one of those readers soon.
Thanks Macgyver

 

once ya do take a look at these threads .

https://www.f150online.com/forums/sh...threadid=66132
https://www.f150online.com/forums/sh...threadid=65581
https://www.f150online.com/forums/sh...threadid=64972

 

mouse Trap,
Welcome to the boards. This section is the best.

 

Thanks guys for all the help, I just rented a scanner and I got the following:

KOEO Code 34
EVP sensor voltage above closed limit
KOEO Code 10

KOER Code 41
Heated oxygen sensor, signal lean, right side
KOER Code 34
EVP Sensor voltage above closed limit

thanks for any input, I'll be doing some research on it tomorrow.

 

You need to unplug the vacuum line from the EGR valve and attach a hand vacuum pump to the valve. Apply and release vacuum to the valve several times. Reconnect and retest. If the code doesn't come back, the EGR valve is sticking, and can be cleaned, but should be replaced. If the code does come back, the next step is to substitute a known good EVP sensor on the original EGR valve, and retest. If the code does not return, replace the EVP sensor. If it does return, replace the EGR valve.

Me personally? I'd just replace the EVP/EGR and be done with it.

No such thing as a code 10, and the code 41 could be the result of a faulty EGR.

Sure has been alot of these lately!

Take care,
-Chris

 

Correct me if I am wrong, but I should feel some vacum from that little hose going into the egr, right? It doesn't feel like any vaccum is there. I'm going to have to pick up a vacum gauge to test it out.
I don't particularly think that is what is wrong because the previous owner replaced the egr and the sensor (it looks new) on a hunt for the reason a ses light was on, which I figured out to be an exhaust tube being broken off that went into between the cats.

Thanks for all the input!

 

no there is no vacuum at that hose at an idle . during koer test it'll get a short burst of vacuum but you'll need a guage to see it and have to be watching for it . just because the egr and evp look new means nothing . i have a brand new one i just bought and put on a week or so ago and it is sticking and i am still getting a code from it . so "new" doesn't mean it "Works".......lol
i can use the hand pump on the egr and the code clears for a short while but then it returns . which indicates the egr is sticking and the evp is ok.

 

mousetrap,
sorry i cant help you with your problem but i have a question for you. how do you like the 351/C6 combo? what kind of mpg do you get? thanks!

 

Cool thanks guys, how do I clean it if it needs it, I am going to try to pick up a pump tomorrow to work on it.
I shouldn't really talk about the 351 c6 combo, because I am getting about 7 mpg, but it has been reliable, wanna buy mine????
thanks all