My chore truck is a 1996 Chevy CK 1500 silverado with 5 liter engine. Last few days it has developed a problem. If it sits and cools off when I restart and take off it will bog and not go over 30 MPH. When I push the throttle over 1/4 it will just not accelerate. If I stop and shut the motor off then restart it runs fine. Truck has 190000 miles, new fuel pump, fuel filter, plugs, wires and cap and rotor 5000 miles ago. I checked for codes, none. Thinking maybe fuel pressure regulator sticking when cold?
- Thread starter MN Scott
- Start date
Super-H-Mike
Member
Ignition switch was a problem in those years.
Brian Allen
Well-known Member
Were the plugs set to the right gap for the truck?
My truck would act up, found the plugs gapped to 0.070".
Runs great now!
My truck would act up, found the plugs gapped to 0.070".
Runs great now!
Hobo,NC
Well-known Member
- Location
- Sanford, NC
I would hang a fuel pressure gauge on it.... If you installed a new pump and find it to be a fuel pressure issue I would take a good look at the tank....
I would also look good at the connections were the fuel pump relay plug into for damage...
dirtpusher
Member
I would agree with the catalytic converts. I have experienced this on my 90 and 95 chevy.
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farmer boy
Well-known Member
My first thought with any 1st Gen Vortec is the fuel pump. They can go bad very quickly. Check the fuel pressure at the schrader valve. Does this truck have the updated spider assembly? I had a simliar issue that went away when I replaced the pump. It would stumble and not accelerate over 3000rpm. If I put the truck in neutral, turned the key off, then back on, the issue went away for a while.(could be 20 minutes, could be a day) If the truck starts, it likely isn't the PFR, because cycling the key likely wouldn't help. The fuel pressure needs to be ATLEAST 58 psi to start,(more is better) and no lower than 50-52 psi to stay running.(again more is better) When you shut the truck off, keep reading the pressure. It should stay put. It could do down in 5 minutes, it may hold for 24 hours. If it holds for anything less than 20 minutes, clamp the rubber portion of the return line as you turn the truck off. If it holds, the FPR is the problem, if it doesn't, there's a leak internally, agian, likely the FPR. My bet would be the fuel pump. Have you had trouble with the fuel pump before on this truck?
I replaced the fuel pump a year and a half ago. It has 5000 to 6000 miles on it. At that time it would not start when cold without cranking it alot. Pressure gauge revealed low fuel pressure. Replaced pump and it starts with a touch of the key as it still does. I don't know if the spider has been upgraded, my guess is no. I have been busy this week but I will get a gauge on it and do your tests. Its getting worse every time I drive it but once I cycle the ignition it does not repeat until I shut it down for awhile. If it were the cats plugging up cycling the ignition would not fix the problem would it?
If the cats were plugged shutting the engine off and restarting would not fix the problem would it? It always has its no acceleration issue right after I start it cold. I then shut the engine off and restart it and it will run fine until I shut it off and it cools off and I restart at a later time. If the fuel pressure checks out I guess I will pull an O2 sensor and install a gauge and check for backpressure. Thanks for the tips guys.
farmer boy
Well-known Member
Can't see that cycling the key would make a cat issue go away. I'm leaning towards the fuel pump being the issue here. They are a troublesome piece of shite. They should have been recalled and had a decent pump put in them. I can't imagine the amount of money spent on tows to fix this problem, let alone the cost of the pumps and labour. What brand of pump was the replacement?
Hobo,NC
Well-known Member
- Location
- Sanford, NC
I take it that it bogs down on take off... Try different accelerator positions on take off... I find most issues to be under very light steady throttle... What you are trying to do is find a pattern you can duplicate over and over.. I have ran into a steady stream of metal tanks full of rust and stopping up the tank strainer are prematurely waring the fuel pump out (even new ones).... They all act like yours just like you described it...
I am not sure if your tank is metal... If you take your new fuel filter off drain and find brown gas on the inlet side I would look good at the tank... I have seen were this issue would take some driving keep the gauge hooked up. I think if its a fuel issue you will diffidently see it on the gauge if not you can move on to other things the fuel test is simple and free....
Update. Truck acted up today with the fuel pressure gauge attached. Pressure will bump up to 60 when it starts then settles at 53psi. When I go to accelerate pressure does not bump up but actually drops to 50 psi when the truck stumbles. When I shut it off and restart the pressure returns to 53 psi but will bump up to 60 when I give it throttle and truck has power. So I'm thinking its a fuel pump issue. When I replaced the pump 6000 miles ago I installed a new tank, fuel filter, Delphi pump with new sock.
Hobo,NC
Well-known Member
- Location
- Sanford, NC
How about the fuel pump ground wire were it bolts to the truck frame recheck it, remove, clean and make sure it has a stare washer. Did you do just the pump are replace the sender assy. Did you drop the tank are remove the bed. Did you replace the fuel pump relay. Do you know what a drag test is for the relay and fuel pump harness connections. A drag test,,, you need the proper terminal to do it about the only way to get the correct terminal is to cut one out of a old relay they are a beach to butcher... Push the terminal in all connections it should have some drag if not the plug in will have to be repaired are replaced... If so I cut the harness out of the relay center and salvage the connectors from a doner harness and wire it up out side the relay center... I have also seen the fuel lines kinked at the pump... Those pumps pull about 6 amps if you have away to check amp draw check it. The pump wave form can also be checked but it takes high dollar tools to do it 
... Looks like you are going after the pump and lots of things to check maybe you will find the issue at the pump are sender asy...
... Looks like you are going after the pump and lots of things to check maybe you will find the issue at the pump are sender asy...Similar threads
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