Husker6.5
135' diagonal 16:9HD, 25KW sound!
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No crank with whining noise
- Thread starter Landon730
- Start date
Husker6.5
135' diagonal 16:9HD, 25KW sound!
Now that it starts, what makes you think you need a new PMD or accelerator pedal assembly?
Husker6.5
135' diagonal 16:9HD, 25KW sound!
Lesson One. When trying to trouble shoot ANY vehicle electrical problem, FIRST make sure the battery(ies) is/are FULLY charged.
MrMarty51
Well-Known Member
After You get that HF multimeter for $1.98, be sure to check the output of the alternator.
Landon730
Active Member
Sometimes when you start it it runs wild but dies as soon as you turn the key off, so I know she ain’t a runaway. Other times when you start it. It will run at 1000 rpm and when you press the pedal it surges to 2000 and back down and back up etc. have a good spare pedal and pmd.
ak diesel driver
6.5 driver
That could also be an IP issue. Hopefully not.
Husker6.5
135' diagonal 16:9HD, 25KW sound!
From what little you've described, I'd be.looking hard at the IP being worn out. Unstable idle, "racing" under light throttle, erratic throttle response all point more to the IP than the pedal position sensor or PMD. PMD symptoms are mainly stalling and dying while running, with restart after cool down. Pedal position sensors will cause uncontrolled runaway and/or no throttle response. GM changed the pedal sensor design mid production in '94 to introduce a "fail safe" third sensor to the cluster and changed the ECM programming accordingly.
Husker6.5
135' diagonal 16:9HD, 25KW sound!
FYI, the life expectancy of an IP is 150,000 miles, injectors 100,000 miles. Judging by the condition/problems you've encountered so far, I'd say that the PO didn't give a hoot about either's mileage or condition.
Landon730
Active Member
The first time it started it ran great. I killed it so I could hook the driveshaft back up(from being towed with tow bar) and when I started it back up it started doing it. I have a spare manual injector pump and maybe electronic. Also sore injectors. Motor sposedly was rebuilt 100,000 miles ago. Pump and injectors are gonna be last thing I try. Gonna try the pedal first just cause it’s easiest lol. I’ll let you know what happens tonight
Paper clip and read codes. Did you drain tank and put fresh fuel in? New Fuel filter? Clean the grounds esp on the IP and the passinger corner of the block has 2 grounds. And as always clear return line to look for air.
Landon730
Active Member
Didn’t put fresh fuel in. Fuel looks clean and smells good. Fuel filter is ok. Don’t have any service engine lights or service throttle lights on. Not sure about return line but the truck did already run fine once.
Look for codes even w/o light. Some don't turn the light on...
Before throwing parts and time at this get it running on new fuel. It's the cheapest thing to try. We have no idea how old the fuel is unless you have better info on that? Old fuel has problems and IP's that are fuel lubed can act up on bad fuel that's lost it's lube. Filters plug. Just saying from the 'major fuel problem king' myself.
Before throwing parts and time at this get it running on new fuel. It's the cheapest thing to try. We have no idea how old the fuel is unless you have better info on that? Old fuel has problems and IP's that are fuel lubed can act up on bad fuel that's lost it's lube. Filters plug. Just saying from the 'major fuel problem king' myself.
Landon730
Active Member
Ok I’ll put some fresh fuel in it. I still wanna try the pedal as it’s easiest, fastest and cheapest because I have about 3 of them laying around. I’ll get some fuel still though because of the reasons you listed I’ll let you know how it goes after school today
Landon730
Active Member
I'm having uncontrolled runaway and no throttle response. Turns out it was MANUAL pump pedals that I had. I don't have enough cash right now to try the APPS so I guess this project will be on hold for a while. I'll let yall know if it's fixed as soon as I can get my hands on a new APPS
After going through all this above don't start throwing parts at it now. The throttle (APPS) isn't floored to give you a runaway. I doubt your APPS is the problem. Unplug it and I bet same issue.
PMD's can and are known to fail and cause wide open. So are pump issues. Where is the PMD? Still on the pump or was it relocated to intake or elsewhere?
Landon730
Active Member
I unplugged it and truck idles better then ever, like I said, won’t have cash for one until October unless I come up with something to do for someone. Anyways I think the APPS will fix it after unplugging it and truck idling great, I have a video of y’all would like to see her running?
Landon730
Active Member
Also pmd is relocated to intake and I put a spare on and that made no difference. PMD is fine so far. I have PLENTY of other known good pumps to put on it if need be. That’s the LAST resort as it’s most time consuming in my opinion especially without a shop and as limited as I am on tools
Will L.
Well-Known Member
In the mean time of waiting for payday of new pedal, (which i would say get the $3 harbor freight meter and test it first)
Remove,clean, and secure all the grounds. Bad grounds is super common and can create all kinds of wierd running issues. And that is free.
You can’t think of diesel fuel as ling term stable like it used to be- it is not. All diesel now has alcohols in it which evaporates off and the remaining fuel sucks. Drain out all the old fuel. Give it at least 10 gallons of good stuff so any remaining crap get mixed into enough fuel to keep the numbers up. You could hold it in some fuel cans a couple
Weeks until you see if that fixes it. If you then determine the old fuel is ok, then pour it back in- otherwise chuck it.
Do you have clear line on the ip return line yet? If not you need 6” long piece of 1/4” clear tubing from any hardware store. Then you can watch for bubbles. Yes air in line can caues this.
And can’t think of too many times the APP is toast and no code for it.
These guys stayed with you when you were fixing to rip
The engine out and walked you through it. You seem to be fighting them every step of the way. Just roll with what they are saying, thy aren’t misleading you.
Remove,clean, and secure all the grounds. Bad grounds is super common and can create all kinds of wierd running issues. And that is free.
You can’t think of diesel fuel as ling term stable like it used to be- it is not. All diesel now has alcohols in it which evaporates off and the remaining fuel sucks. Drain out all the old fuel. Give it at least 10 gallons of good stuff so any remaining crap get mixed into enough fuel to keep the numbers up. You could hold it in some fuel cans a couple
Weeks until you see if that fixes it. If you then determine the old fuel is ok, then pour it back in- otherwise chuck it.
Do you have clear line on the ip return line yet? If not you need 6” long piece of 1/4” clear tubing from any hardware store. Then you can watch for bubbles. Yes air in line can caues this.
And can’t think of too many times the APP is toast and no code for it.
These guys stayed with you when you were fixing to rip
The engine out and walked you through it. You seem to be fighting them every step of the way. Just roll with what they are saying, thy aren’t misleading you.
Husker6.5
135' diagonal 16:9HD, 25KW sound!
Husker6.5
135' diagonal 16:9HD, 25KW sound!
Uncontrolled runaway and no throttle response are classic signs of an IP on its last legs. You get no throttle response when it goes runaway (won't idle down when you release the accelerator pedal) because the IP is mechanically seizing from wear and the stepper motor can't over come the resistance. I can't ever recall either the early series '94 APPS or the late series '94 APPS NOT setting a code when they go bad. The early '94's were upgraded to the later style APPS and the PROM reflashed/replaced with the updated program to work with the new style APPS on a factory recall (IF the owner brought it in). If the APPS was bad, it would have set a code for it.
Meanwhile, Will's suggestions should be undertaken. Yes, bad ground(s) can cause some crazy things to happen on these trucks. The clear fuel line is a great diagnostic tool and entrained air in the fuel can cause all sorts of idle/surging problems, too. But as somebody who has owned a late '94 since 2002 and over 220K miles and has replaced a couple of IP's that have worn out, as well as the ones on my 98, you are most likely looking at replacing the IP whether or not you want to accept that.
Meanwhile, Will's suggestions should be undertaken. Yes, bad ground(s) can cause some crazy things to happen on these trucks. The clear fuel line is a great diagnostic tool and entrained air in the fuel can cause all sorts of idle/surging problems, too. But as somebody who has owned a late '94 since 2002 and over 220K miles and has replaced a couple of IP's that have worn out, as well as the ones on my 98, you are most likely looking at replacing the IP whether or not you want to accept that.