Choking/fuel problem


#1

I’ve got a problem with my 1999 F-250 Superduty.When I step on the gas the motor chokes out like it is not getting enough fuel.When I run it on high RMP’s the engine does not choke out.I’ve changed the fuel filter and checked the air filter both are fine.Is there anything else that I can check on my own without hooking it on a machine?



I can not afford taking it to the garage at the moment and was hoping to fix it myself.



Thanks in advance!

Steve.


#2

The odds aren’t very high that this is the problem, but it is easy and cheap to try. Try cleaning the MAF sensor.


#3

You might want to have the fuel pressure tested.

If the fuel pressure is low, the engine will high-idle all day. But if you put a load on the engine as in putting it gear, and then step on the accelerator, the engine will lay down because not enough fuel is being supplied for that condition.

Tester


#4

I’m afraid I don’t really know what a MAF sensor is?
Steve.


#5

When I push down on the accelerator it actually runs good but when I maintain speed it chokes.


#6

The MAF sensor is an airflow sensor mounted usually in the air fllter box or thereabouts. It measures the amount of air flowing in. It’s signal is one of the signals that the ECU uses to correctly meter the fuel. It means “Mass Airflow”. You should probably get a Haynes manual before starting any work at home.

Anyway, while that’s a great suggestion I’d recommmend stopping by the local parts store and try for a free reading of stored codes. Any thing that causes erratic operation should store fault codes.

Post the codes here.

By the way, your reply to tester is inconsistant with the original post and would lend me to suspect the EGR valve sticking open, whereas I too thought of poor fuel pressure based on the original post. Perhaps some clarity would help.


#7

This is a gasoline engine, right??


#8

sorry about that-it starts fine,it idles normal,when you take off it runs good,as you maintaining a speed of about 45-50 miles per hour it sputters a little.I can usually clear it up by running RMP’s higher temporarily.
Yes,it is a gas motor.


#9

Try a fresh set of spark plugs. It sounds like weak spark, or weak fuel pressure. Check the fuel pressure by running the engine at a load and rpm equal to 45-50 mph. If it has a manual transmission (or, even, an automatic transmission), you can raise the drive wheels, attach the fuel gauge, run the engine up to that rpm, load the engine with the brake, and read the fuel pressure. If the fuel pressure falls off, it may be caused by the fuel pressure regulator, or a weak fuel pump.


#10

Bought the spark plugs,have yet to put them in and I do not have a fuel pressure gauge.Steve.


#11

It may be as simple as new plugs and distributor rotor and cap (if this system is distributor based).

Kit may be right about the fuel pressure regulator or pump too, although I’d expect that to show up more on acceleration.

A stuck EGR valve will generally cause rough idle, so whil it’s still a possibility I’d be inclined now to dismiss it.

There are other possibilities like an oxygen sensor, a MAP sensor, and even a crank speed sensor, although none of then fits the symptoms exactly.

However, the good news is that you have an OBD-II OnBoard Diagnostic system. Whatever is causing the rough running should be storing codes. I still suggest getting the ECU checked at a parts store.


#12

I tried getting the codes checked today but the Autoparts place told me that they could not check itunless there was a light that came on which is not the case.
Got to return the new spark plugs that I bought today-turns out it is fuel injected.It has a 5.4 liter motor.


#13

See if it is time for a new air and fuel filter also. Handle the plug wires gently and pull off by the boot only. If you have trouble getting the plug wires off you may find a boot puller helpful Also do one plug and wire at a time to prevent connecting the wires incorrectly.


#14

Were the plugs you bought for a different engine? in what way were the plugs and engine different? It should be no suprise that the engine is fuel injected. Last domestic carb. from FORD was probably 1979 or so. Had a 77 Cougar that was carbed.


#15

Your spark plugs should be selected from the plug manufacturer’s listing for your particular year, make, model and engine. This sort of an error is a “red flag” to me. It, combined with your earlier posts, suggests to me that perhaps the repair would be better performed by someone with more automotive knowledge. No disrespect intended, I’m just trying to give responsible advice.

Check with your local community college (talk to the department chair) and see if they can use it in a lab class for their automotive students. If they will it’ll likely be free labor and a steep discount on the parts.


#16

Already replaced both.


#17

I agree-however all of those with that particular automotive knowledge charge for it and I can not afford it at the moment as I said earlier.


#18

Try the community college. Or even a high school automotive program.