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11-26-2023, 10:54 PM | #1 |
Registered User
Join Date: Mar 2008
Location: Tullahoma, TN
Posts: 406
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Re: P0300 Requesting Advice
The fuel pressure is 60psi with the switch on and at idle. When I turn it off the pressure remains steady at 60psi and does not drop. However, when I rev it up the pressure only goes up to 65psi regardless of how high I rev it. Is that correct, or should the pressure continue to increase with the rpms?
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12-20-2023, 11:59 AM | #2 |
Registered User
Join Date: Jan 2006
Location: Smithfield, VA
Posts: 1,501
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Re: P0300 Requesting Advice
You mentioned NOTHING about the cap and rotor. I'll put money on 2 things. That's the problem and the other is your vents are plugged.
When I had the original factory distributor, I was running fine one day and it wouldn't start the next. Changed both and good to go. Check it out and see how bad they both look. You'd be surprised. |
12-20-2023, 08:33 PM | #3 |
Registered User
Join Date: Mar 2008
Location: Tullahoma, TN
Posts: 406
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Re: P0300 Requesting Advice
I did not check because I'm getting good fire at spark plugs. But I will check tomorrow anyway. On the scanner it shows that it is cylinders 3 & 5 that are misfiring, if that helps anyone help me. Also, the long range fuel trim is 17% on bank 1 and -5% on bank 2, but I don't know if that is good or bad or if it means anything.
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12-22-2023, 06:48 PM | #4 |
Registered User
Join Date: Apr 2018
Location: Carpenter, Wyoming
Posts: 83
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Re: P0300 Requesting Advice
This may not be helpful. I replaced the engine on a 1996 K1500 with a factory crate engine. When replacing the engine, I replaced a lot of parts including cap, rotor, and wires. A couple years later I was on the on ramp accelerating on to I80. The truck totally died and would not restart. I had it towed home and began working on the problem. I had 16,000 miles on the cap and rotor........so I was sure it wasn't that. I did a post with pictures on this site years ago. The cap and rotor looked fine. I tested the continuity on the cap and it was also fine. I checked for spark on all cylinders and had zero spark. Bottom line I replaced the cap and rotor and the truck fired up and ran perfect. It was not a cheap cap, and had bronze contacts. You have spark, but is a full spark or weak. I have a hard telling the difference.
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12-24-2023, 04:44 PM | #5 |
Registered User
Join Date: Mar 2008
Location: Tullahoma, TN
Posts: 406
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Re: P0300 Requesting Advice
SOLVED!!
I replaced the Cap and Rotor Button and it fixed it!! Thank you guys for recommending that I try replacing those!! Y'all were right!! I would have bet $10,000 that was not the issue. When I pulled the plugs out and started it, fire would jump two inches to the manifolds. There was no way that I thought that fire was the issue, but it was, the cap looked corroded and the rotor was a little burned on the end. I put in new Cap and Rotor and blew out the vents (they were not stopped up) and only #5 was showing a misfire. I pulled that plug out and hit it with a wire brush. fired it up and BOOM! No code and no misfires on the scanner!! That #5 plug would have probably cleaned up going down the road, but anyway, I'm good now and thank you guys so much, because I was within a hair of buying intake gaskets and a new fuel spider and spending my Christmas break on that. One last note for future people: Back when I was trying to figure out what was wrong, trying to diagnose, another thing I noticed, #3 & #5 at the manifold would never get over 200 degrees and all other cylinders were about 400 degrees. That could have been a weak spark that made that difference. IDK, but I'm glad I got my truck going again. Thanks Again guys!! |
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