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1996 K2500 runs rough

79jasper

Active Member
Messages
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244
Location
El Paso, TX
So finally had a chance to look at my buddies truck.
He has done Leroys psd and relocate, new lift pump, has a new alternator, new Accelerator Pedal.
It has a very touchy throttle. In the video, I wasn't even giving 1/4 throttle. If you drop it into gear, it will idle down and stay there, until you touch the throttle again, and the rpms will stay up.
I also noticed the FSS is leaking.
And, I believe the transmission range sensor is bad. A few times going to start it, Wouldn't start unless I dropped in into neutral.
No check engine light, I tried using torque, no codes stored either.

I'm thinking of leaning towards the ds4, but I don't have as much experience with those as I do the mechanical pumps.

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I'll check them next time I'm over there.
It does start right up. It was down in the 40's today.

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It does sound like a fuel solenoid problem in the pump, but do the obvious checks 1st just to be certain. Make sure the lift pump is supplying pressure, put a piece of clear hose on the injection pump return to check for air bubbles, grounds Grounds and GROUNDS, make sure they're all clean and hooked up(none broke off), and if you have a scanner try to watch the solenoid closure time to see how much ir jumps around if any.
 
"I also noticed the FSS is leaking."
This can be the source of air. As mentioned eliminate air by the clear return line check as step #1 and then and only then step #2 is trons: grounds, filter harness removal etc. Grounds are always good advice, but, air free fuel is step one.
 
Maybe this weekend I can have the time to work on it more.
Definitely wanted to try the clear line to check for air.
Once it ran a bit, it smoothed out some. Which I figure is mostly from air getting in at the FSS. From what I can tell, it's the older version with the Allen head.
But still had the touchy throttle.

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i have a 95 that I am working on that has a very touchy throttle as well. I have had it in the garage for a few days for other problems but I did find a broken ground wire so I will take it for a drive tomorrow and see if the broken ground was the problem
 

I am barley on the peddel when it reves way up, like what in my truck would bring the idle up a couple hundred. Also the idle is very rough it does have pretty old fuel in it, (at least a year old) but I'm starting to think the injection pump maybe the culprit here

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Get your own thread. Lol just kidding.
Haven't been back over to my buddies to do more diagnosing on his.
Normally one would maybe think tps (as his even had a code for it) but even with a brand new tps, made no difference.

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Huh. I guess I didn't link the video of it.
It shoots up a bit faster.

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I'll still probably check for air intrusion.
But he's learning towards just buying a ip and having me swap it.
I'm working on talking him into a good one, not a parts store reman.

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Yup. I know of a few places to avoid with the db2. I'll assume basically the same with the ds4. Lol

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Well i put a known good used pump on last night off a buddys truck and that fixed my problems.
Runs nice and smooth and throttle is not touchy.

On a side not while bleeding the air from pump and lines i was just starting to see fuel at the drivers side injectors (had them crackled a bit) heard a strange sound and then stopped getting fuel. Cranked it a few more times and had fuel running all over the floor from the valley drain get to investigateing and find this what I'm guessing is a bleed screw broke off. Not sure how it broke but i put a differnt one in from old pump. Of course you can't get to the dang thing without taking the intake off but at least i was able to get the broken piece out with a screw driver
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I didnt really take a good pic but there is a screw that takes a t40 in the top of it wich would act as a bleed screw

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