Ami Hufford

Hi all,
I'm new here and decided I needed to consult a community of Chevy lovers to figure my problem. My name is Ami and I own a 1995 Chevy Silverado 2500 with a big block 454. It's 2 wheel drive with an extended cab. I love this truck and have been searching for answers as to why it isn't working right for the past three years. I'll start at the beginning though.
I bought the in 2012 when I got out of the military. It's gotten me through hell and back as well as years of moving. Three years ago while I was living in Florida it started having some issues with wobbling idle speeds. When I bought the truck it would reach 30 mph sitting in neutral so it started out with a high idle. When it started wobbling it revved to 1200 rpm then dropped 200 rpm and loop like that continually for a couple minutes until it would level out at 1000 rpm. It was odd and I was concerned so my dad suggested a hole in the diaphragm for the idle air control, or that it needed adjusting (I did look that up and found out you can't adjust idle on that year truck). Then it started stalling out. It would start, the idle would wobble, it would hit 200 rpm then just die. But I could always get it started up again. So my father in law looked at it and found some faulty injectors. We replaced them, problem persisted. So I got some fresh plugs and wires and distributor. I gapped the plugs to manufacturer specs, and labeled the wires based on the manual's diagram. Then I took the cap of the distributor. It looked like the distributor had been full of water which is inconsistent to the truck's previous life of hauling campers for a dealership. Then we took the old plugs out and they crumbled in the socket (luckily not in the engine). So I replaced everything. The truck ran a little better but still had the idle wobble and was running really rich. Then I had to move from Florida for health reasons. I got to Kentucky when I had to replace a battery but the engine sounded like a freight train. You know the slow big diesel engine looping noise that freight train engines make when they are moving slow along the tracks. That noise. But the truck didn't have an issues maintaining interstate speed while under a load as I have horses I was moving in an old 30ft stock trailer (12,000lbs gross weight). After the move it started the stalling problem again. It also took two cranks to start it as it would stall on the first crank. I took it to a mechanic my mom trusted and he said it was a throttle body problem. He then in that same span butchered my current throttle body trying to fix the issue. Still had issue of looping, wobbly idle, and stalling even while going down the interstate with cruise set. So I do an old trick my dad taught me and that was to flip the lid over the air filter so it can get more air. Stalling subsides but new issue arises. Oil was coming through the butterflies on the throttlebody and coating my air filter and pan. I am at a lose so I park it while I go back to work (OTR Truck Driver). One day I do an oil change and notice brass glitter in the oil. Take it to another shop and they say bearings and bad and do an Engine swap. So, now I have a brand new Jasper 454 engine in my truck. We had to connect the other old parts to it like the throttle body and what not as I was only replacing the block and internals. I pick up the truck and they tell me that they had to set the timing back so the truck would start. Once again I am at a loss. Here is where I'm struggling. New engine still looping, still stalling, still had wobbly idle. It isn't running as rich anymore but I still have to flip the air filter lid. When it stalls now it seems like all power just stops. It shuts completely down even while on the interstate. I can pop in neutral and do a rolling restart and its just fine after that. I am at such a loss as to what is causing the problem. I've hooked up a diagnostic tool to it and it is saying ignition issue and that is the only code it is throwing. I am open to any kind of ideas or thoughts as to what to do next. I also have not tackled the throttle body idea as finding one for a mid 90's 454 is not easy and the second mechanic suggested it might not be the culprit. Since the TBs I have found are so expensive I want to make sure that it will make a difference first. So, anybody out there with mid 90's 454s have this problem before? Picture of truck in question below with trailer attached. I also want to note that the truck had been custom order from Chevrolet by previous owner with a beefed up drive train, rear axle, and suspension just for hauling heavy 5th wheel campers.

Irish_alley

First, Thank you for your service.
what code came up with your "check engine" light?
have you clean your grounds good?
pretty much all the issues your having can be caused by all the sensors on the engine except the CTS.
does it do this all the time or only when cold or hot?

http://forum.73-87chevytrucks.com/sm...?topic=29996.0

i dont see why the air filter cover has anything to do with it, but hey if it works lol

Kazoocruiser

Welcome to the forum. Sorry you are meeting under stressful conditions for you. The new block eliminates the "air pump" side of the equation. How many miles are on the odometer? From the picture, it looks like maybe the fender on the passenger side got hit. Is that correct?

What I am going to suggest that you do is check your fuel pressure at the rail access port. It should show a reading of about 45-55 psi during running conditions. When you turn off the key, the pressure should remain for some period of time before bleeding off. The meter should jump immediately to the 45-55 psi indicated when the key is turned to the "run" (not start) position.

If you have a clogged fuel filter, that might cause some problems. The vehicle is almost 25 years old, and parts reach service limits. The fuel pump could be trying to push fuel through a clogged filter.

Have you pulled any codes with a scanner, and if so, what codes have you found?

As I recall, sometimes a manufacturer uses a fuel rail pressure sensor signal input to vary dwell (on) time of the pulse width of the injectors. If it's bad, it will give the symptoms that you are describing. The problem is, that maybe a wire got cut controlling the signal somewhere in the truck's history. So you are going to need a wiring doctor to verify voltage and ground-path circuits. Loose grounds are something you can check for with a multimeter, and will give you all kinds of problems until they are eradicated.

Keep us posted.
/s

Irish_alley

TBI motors are only 12-15 psi

Kazoocruiser

Sorry, it wasn't clear to me that the vehicle was a TBI unit. The advice about checking the fuel filter is still valid.

Irish_alley

yup, sure is. most fuel pump failures can be traced back to a poor filter and the pump having to pump through a clogged filter will cause it to work harder and fail. on a side note these tbi pumps dont have a check valve from what ive worked on

kr4kk13

look into getting a tire valve stem and take out the valve. put the fat end of the stem over the end individual injector where it sprays into your intake manifold. you have to remove the injectors to clean them. Take brake spray and glue the red spray straw into the valve stem entrance. now your gonna clean injectors BACKQARDS...


WHen you spray the carb cleaner into it will fill up. use a 9 volt to tap against the two prongs avctivating the spray backwatrds which will come out of the holes where the screen is.

also the fuel regulator which is a diaghram and a spring many times bogs down Look into getting a nother one or an adjustable unit from either junkyard or from online. When you go to put TBI back on rememeber its a 454 many parts and gaskertes are interchangeable with 305 and 350 Small blocks but the universal size of the opening where the valves are is bigger on the 454


also your iac and tps needs mulitmeter to check ..... AND CLEAN AND REPLACE your GROUND straps on engine block to firewall and engine block to frame and to battery. THese get corroded inside the strap and wire coating and you dont even know it. SHiny metal to shiny metal or no workieeeeee



Vet to Vet THanks. this took me 100 PPLUS HOURS OF FRUSTRATION NOW IF YOU DONT MIND IN HAVE A OIL PAN TO DROP DUE TO MY DISTRIBUTOR BOLT GOING INTO THE WRONG HOLE