LS1LT1 Forum banner

1 - 3 of 3 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter #1
Hey guys, I am hoping that someone can shed some light on my problem. So I have a 96 Chevy K1500 with a 350. Back in November I had the lower intake manifold, spider assembly, and new fuel regulator installed by a local garage with someone i trust. About a month and a half later it throws a check engine lights and runs for crap. Checked the code and it said cylinder 7 misfire. So I replaced cap rotor plugs and wires. It was good for about a week and then it started acting up occasionally with the same code. About 3 weeks ago I decided to check fuel pressure and aha there's the problem. I check it 3 different days and the first day when turn key on pressure would go to 58 and slowly dropped to 48. the other days it was 58 and 56. OK so it has to be fuel pump because reg is new, week ago replaced the pump and filter with Delphi. Fuel pressure is still 58. :craz28:Ok got the garage to warranty the reg and that was done yesterday and he didn't check the pressure after he was done. Today its surging and backfiring again occasionally so I checked the pressure and its still 58:confused: When you start it pressure drops to 40 and if you rev it pressure goes up then back down. I sure hope someone can help because I'm at a loss. Thanks in advance everyone!
 

·
Global Moderator
Joined
·
13,240 Posts
You need to put your truck on an obd2 scanner capable of real time sensor data. Since I don't know what fuel pressure on a 96 truck should be I can't say that 58 is wrong.

It sounds high as lt1 engines are around 43 psi, but I don't know for sure. See what your sensors are saying and get back to us.

Also spray your plug wires with a little water and run at night. Look for the spark leakage light show. Also make sure all plug wires are connected to the correct spark plugs.

If you haven't a clue as to what scanner readings mean, pm me with your e-mail address and I'll send you the pdf file of "scanner readings and what they mean". It is primarily for lt1 engines but the data means the same for a regular 350 also.

If fuel pressure is too high, I would check the return line for kinks and restrictions that would imped the flow of fuel back to tank. Also remove vacuum line from fuel pressure regulator, plug the vacuum line, and run engine that way as a test. Fuel pressure should go up with vacuum line disconnected.

If it doesn't, you still could have a bad fuel pressure regulator, or the blockage of fuel return line I mentioned above.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #3
Thanks cocobolo95 specs on fuel pressure should be 60-66. The first time I had to replace the fuel pump the pressure had dropped to 56 and it would not start. The plug wires were replaced already and the regulator does not have a vacuum source. The basic tune up was the first thing I did. The problem with its running is not constant. Most of the time when it does act up you can just feel the surging but sometimes it gets worse and starting backfiring and when that happens I have found that if you throw the pedal to the floor for a sec then its fine.
 
1 - 3 of 3 Posts
Top