Fuel Issues
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Joined: Oct 2003
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From: Ashland City, TN
Fuel Issues
I'm having a fuel issue.
Best way to explain it, it acts like the choke is stuck on. I'm dumping way to much fuel. I'll even occasionally get stutters.
I can't give an RPM reading, no tach, but it sounds like its idling around 1500-2000.
After driving and shifting out of gear, it will stay reved up for anywhere from 10-30 seconds, sometimes it will never rev down. But it rev's down to around 1000 RPM's
Tottaly irritating, because its killing my fuel economy, and when you try and slow down, the truck doesnt slow down without the break due to the high idle.
I've replaced, in the last year, TPS, IAC, CTS.
These are the only things I know associated with fuel sending.
I used to be able to just shut the truck off and turn it back on before the CTS, which fixed the problem for a day, and now nothing seems to trick the PCM.
No MAF, so even a computer reset on the SD system should make it send default fuel commands, which it currently isn't.
so, PCM resets dont work either.
No, I cannot pull codes.
And I have no O2 Sensor, but that shoudln't make any difference on Fuel if you reset the PCM. It should default, instead of adjust.
I have true duals, so I decided not to install the o2 sensor due to it would only read 1 bank, which isn't a good idea in my opinion.
Best way to explain it, it acts like the choke is stuck on. I'm dumping way to much fuel. I'll even occasionally get stutters.
I can't give an RPM reading, no tach, but it sounds like its idling around 1500-2000.
After driving and shifting out of gear, it will stay reved up for anywhere from 10-30 seconds, sometimes it will never rev down. But it rev's down to around 1000 RPM's
Tottaly irritating, because its killing my fuel economy, and when you try and slow down, the truck doesnt slow down without the break due to the high idle.
I've replaced, in the last year, TPS, IAC, CTS.
These are the only things I know associated with fuel sending.
I used to be able to just shut the truck off and turn it back on before the CTS, which fixed the problem for a day, and now nothing seems to trick the PCM.
No MAF, so even a computer reset on the SD system should make it send default fuel commands, which it currently isn't.
so, PCM resets dont work either.
No, I cannot pull codes.
And I have no O2 Sensor, but that shoudln't make any difference on Fuel if you reset the PCM. It should default, instead of adjust.
I have true duals, so I decided not to install the o2 sensor due to it would only read 1 bank, which isn't a good idea in my opinion.
Fleet Owner
Joined: Aug 2005
Posts: 23,667
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From: Easton,Ks
I will guess that you are talking about a 1995 F-series gas truck.
I thought I knew a lot about the PCM but I have never heard of a reset or reseting it.
So How do you reset it?
Are you saying you can not get the PCM to read the codes at all?
If so your PCM might be bad.
Does your fuel pumps run all the time the key is on without the engine running?
If yes to both you have a bad PCM.
I thought I knew a lot about the PCM but I have never heard of a reset or reseting it.
So How do you reset it?
Are you saying you can not get the PCM to read the codes at all?
If so your PCM might be bad.
Does your fuel pumps run all the time the key is on without the engine running?
If yes to both you have a bad PCM.
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Joined: Oct 2003
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From: Ashland City, TN
I dont have a PCM issue.
PCM should reset if you disconect the power to it?
Maybe I am wrong.
I have a fuel issue.
Fuel pump is fine. Just replaced it in the spring, but the problem was before that as well.
PCM should reset if you disconect the power to it?
Maybe I am wrong.
I have a fuel issue.
Fuel pump is fine. Just replaced it in the spring, but the problem was before that as well.
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
How do you know that?
No that will cause codes.
The PCM will resets itself every time you turn on the key.
If you want to know how to clear the Continuous Memory then you do it like this.
1. Run the Key On Engine Off Self-Test.
2. When the DTCs begin to be displayed, deactivate Self-Test:
Remove the jumper wire from between Self-Test Input (STI) connector and the Signal Return Pin of the DLC.
3. Continuous Memory will be erased in the PCM.
If you think this is the case have you put a fuel gauge on it?
If so what did it read at idle and with the vacuum hose off the FPR?
Was there any fuel in the vacuum hose when you took it off?
Why did you replace it?
Do you have two fuel tanks?
No that will cause codes.
The PCM will resets itself every time you turn on the key.
If you want to know how to clear the Continuous Memory then you do it like this.
1. Run the Key On Engine Off Self-Test.
2. When the DTCs begin to be displayed, deactivate Self-Test:
Remove the jumper wire from between Self-Test Input (STI) connector and the Signal Return Pin of the DLC.
3. Continuous Memory will be erased in the PCM.
If you think this is the case have you put a fuel gauge on it?
If so what did it read at idle and with the vacuum hose off the FPR?
Was there any fuel in the vacuum hose when you took it off?
Do you have two fuel tanks?
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Hotshot
Joined: Oct 2003
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From: Ashland City, TN
Hmm, good. probably should reset the codes then.
Thanks for that info. Will probably fix the problem. I hope.
I'm just trying to find more things to check that involve fuel.
I always get unhelpfull answers. But then, people dont nessarly know whats going on, or what i've done. so it just turns into this big thread of me telling everyone what I have done and what I know is fine.
I could use the readout's for the IAC though to check that. This is the first one i've ever had not get black on me easily, so it could be malfuncitoning as well.
I dont know the correct resistances to mesure to check it.
Fuel pumps go bad, gotta replace them.
I don't have a vacuum issue. I've checked that.
I dont need a fuel guage to know that I am dumping to much fuel.
Thanks for that info. Will probably fix the problem. I hope.
I'm just trying to find more things to check that involve fuel.
I always get unhelpfull answers. But then, people dont nessarly know whats going on, or what i've done. so it just turns into this big thread of me telling everyone what I have done and what I know is fine.
I could use the readout's for the IAC though to check that. This is the first one i've ever had not get black on me easily, so it could be malfuncitoning as well.
I dont know the correct resistances to mesure to check it.
Fuel pumps go bad, gotta replace them.
I don't have a vacuum issue. I've checked that.
I dont need a fuel guage to know that I am dumping to much fuel.
Thread Starter
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Joined: Oct 2003
Posts: 17,799
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From: Ashland City, TN
Awww, shizzle, we going to have to talk more about the Test stuff.
my CEL is burned out.
I never had any luck with pulling codes though lights or the CEL. They dont seem to work out.
BTW, I have OBD-I
I added you on G-Talk, no idea if you use it, or the chat feature in Gmail.
my CEL is burned out.
I never had any luck with pulling codes though lights or the CEL. They dont seem to work out.
BTW, I have OBD-I
I added you on G-Talk, no idea if you use it, or the chat feature in Gmail.
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
To test an IAC just unplug it with the engine idling and the idle speed should drop and the engine may die.
I take it the pump stopped pumping and you only have one tank.
I never said anything about a vacuum issue.
How do you know if you have 42 PSI across the fuel injectors then? Did you take the vacuum hose off the FPR with the fuel pumps on to see if you have a bad diaphragm.
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Joined: Oct 2003
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From: Ashland City, TN
Oh, shazzle. Forgot to mention i replaced the FPR too.
It was bad, but never changed the idle issue.
Still need to reset codes though.
I coulda replaced all this stuff and its still running like crap due to codes.
It was bad, but never changed the idle issue.
Still need to reset codes though.
I coulda replaced all this stuff and its still running like crap due to codes.
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Fleet Owner
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From: Easton,Ks
Codes in CM will not make it run bad, they just tell what is not right.
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Joined: Oct 2003
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From: Ashland City, TN
Guess this isn't helping me solve my issue any then.
Last time I pulled codes on it, it gave me codes that dont even apply to my vehicle.
To my sence, codes would tell the computer what to adjust for.
But thats how I think of it. *Shrugs*
Guess you have no other idea's for things to check then?
Last time I pulled codes on it, it gave me codes that dont even apply to my vehicle.
To my sence, codes would tell the computer what to adjust for.
But thats how I think of it. *Shrugs*
Guess you have no other idea's for things to check then?
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
I do not even know what we are working on, I am only guessing that it is a 1995 F-series but I do not know what engine size it has or what transmission it has.
If you have a fuel issue the only way to get a handle on it is to check the fuel pressure, do the self test and if it is SFI run the engine balance test.
You do not fix it by throwing parts at it, you will go broke that way.
You said that you do not have an O2 sensor, even if it is on one pipe it will still give some feed back to the PCM. I do not understand how you expect it to work right when you take its sensors away. I do not remember the O2 voltages with out looking it up but maybe zero volts tells the PCM lean and if this is the case the PCM will try to adjust the F/A ratio table to go as far rich as it can.