Truck runs fantastic, then multiple misfire the next day?

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Tech-GeeK1500

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So I've got my truck road worthy again after being down almost a year to refinish the frame, body and suspension. My truck is a 1998 k1500 with a 305. During the body on restoration the truck received a new fuel tank, pump and sending unit, filter, distributor cap, rotor, plugs, wires and ignition coil. I drove is last weekend on Saturday and it ran like a dream. Got in it Sunday and almost immediately after I got on the road it started hesitating and misfiring. Also my oil pressure gauge will drop to zero for a couple seconds and shoot back up to 40 psi, it almost does this in a pattern.

Last night I found that my ground strap to the engine block (the strap on the harness for the power steering and crank position sensor) was severely corroded and it broke when I backed the nut off the stud. I repaired the ground and it seemed to help marginally. The picture I uploaded is the list of error codes I got before repairing the ground. After the repair I now am only getting the P0300 misfire code, the ground wire repair seems to have taken care of the other codes. My truck still feels like something is pulling backwards on it when it tries to accelerate. It stumbles and runs very rough yet. It idles at about 550 rpm when in gear, very low. Any ideas?

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Tech-GeeK1500

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I think you're right. My brand new Spectra pump is only putting out around 53 psi at idle. When it primes before I turn the engine over it'll bump up to 60 then immediately bleed off.
 

knucklehead

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Check distributor cap and rotor for your multiple cylinder misfire. My buddies truck was just acting like that after sitting for one week. There was water dripping off the contacts and the rotor center contact had a hole burned thru it
 

joep88cheyenne

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If cap shows water or moisture in it there is a trick I used years ago. Spray the assembled cap and wires when it is all hooked up with wd40. Worked well on many cars I have had.
 

tunedbytuna

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So I've got my truck road worthy again after being down almost a year to refinish the frame, body and suspension. My truck is a 1998 k1500 with a 305. During the body on restoration the truck received a new fuel tank, pump and sending unit, filter, distributor cap, rotor, plugs, wires and ignition coil. I drove is last weekend on Saturday and it ran like a dream. Got in it Sunday and almost immediately after I got on the road it started hesitating and misfiring. Also my oil pressure gauge will drop to zero for a couple seconds and shoot back up to 40 psi, it almost does this in a pattern.

Last night I found that my ground strap to the engine block (the strap on the harness for the power steering and crank position sensor) was severely corroded and it broke when I backed the nut off the stud. I repaired the ground and it seemed to help marginally. The picture I uploaded is the list of error codes I got before repairing the ground. After the repair I now am only getting the P0300 misfire code, the ground wire repair seems to have taken care of the other codes. My truck still feels like something is pulling backwards on it when it tries to accelerate. It stumbles and runs very rough yet. It idles at about 550 rpm when in gear, very low. Any ideas?

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I had the same random misfire issues at one point with my 305 too. I had done a tuneup a few months before, and it started randomly missing. Mine was misfiring in the cap, they are notorious for doing this, even some new caps.


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Tech-GeeK1500

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Awesome, thanks for all the advice guys, I'll take a look at my cap and rotor tonight.
 

Tech-GeeK1500

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Thanks for the suggestion! The new cap and rotor I just installed are AC Delco from Amazon and they've only been on a few weeks. Do you guys think that 53 p.s.i. of fuel pressure at idle is a concern?
 

94burbk1500

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Thanks for the suggestion! The new cap and rotor I just installed are AC Delco from Amazon and they've only been on a few weeks. Do you guys think that 53 p.s.i. of fuel pressure at idle is a concern?
I guess I missed the part where you already did cap and rotor. My truck is tbi, so idk about the fuel pressure, sorry.
 
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