5.3 hard start
Thread Starter
Staging Lane
Joined: Jun 2017
Posts: 56
Likes: 5
5.3 hard start Here is the story: the 5.3 in my 79 Camaro was starting fine and running great. I did rewiring of the entire car and for some reason afterward engine was not starting any more. It turned out the fuel pump went dead! I have tanksinc tank and in tank fuel pump. I changed the fuel pump and car would start but it would take 2-3 efforts, while before it would start right up. When it starts, it runs fine but it doesn't matter hot or cold, if I turn the engine off it would take 2-3 try to start the engine again. I measured the fuel pressure at the rail, and when the ignition is on and I hear the pump, I don't really get any pressure but when engine is cranked, it gradually builds pressure to 20-25 PSI instead of 55. I thought the fuel regulator is bad or clogged for some reason (although I only have 100 miles on the car after the engine swap). I changed the corvette style regulator/filter. Now the car is a little better but still it takes 2-3 try to get it running. Any idea? Idle control? Throttle position?
I have say that before I changed the fuel pressure regulator, the engine made a popping noise while thing to start, like a carburetor back fire.
Thanks for the help.
I have say that before I changed the fuel pressure regulator, the engine made a popping noise while thing to start, like a carburetor back fire.
Thanks for the help.
TECH Fanatic
Joined: Dec 2017
Posts: 1,467
Likes: 265
From: Bossier City, Louisiana
If you either don't have the full time 12 volt "keep alive" power applied to the PCM or you disconnect your battery, the PCM forgets its "learned" parameters from previous times it had been running. Mine is also hard to start if this occurs.
Rick
Rick
Thread Starter
Staging Lane
Joined: Jun 2017
Posts: 56
Likes: 5
Thanks
TECH Fanatic
Joined: Dec 2017
Posts: 1,467
Likes: 265
From: Bossier City, Louisiana
Yes, that was what it was for me. Mine took several starting attempts and long applications of the starter to get it to start. This occurs if I swap PCM's or disconnect the battery for more than a minute or two.
Rick
Rick
Thread Starter
Staging Lane
Joined: Jun 2017
Posts: 56
Likes: 5
If that is the case, how long , how many starting cycles, will take for ecm to reset/memorize new parameters?
TECH Fanatic
Joined: Dec 2017
Posts: 1,467
Likes: 265
From: Bossier City, Louisiana
Three to five cranks for 5-7 seconds. Then it catches, runs rough for a few seconds, gets its second wind and runs mostly OK. Might run with a slightly high idle for longer than usual. Once it goes through a warm up cycle, easy and dependable starting returns as normal.
Rick
Rick
Here is the story: the 5.3 in my 79 Camaro was starting fine and running great. I did rewiring of the entire car and for some reason afterward engine was not starting any more. It turned out the fuel pump went dead! I have tanksinc tank and in tank fuel pump. I changed the fuel pump and car would start but it would take 2-3 efforts, while before it would start right up. When it starts, it runs fine but it doesn't matter hot or cold, if I turn the engine off it would take 2-3 try to start the engine again. I measured the fuel pressure at the rail, and when the ignition is on and I hear the pump, I don't really get any pressure but when engine is cranked, it gradually builds pressure to 20-25 PSI instead of 55. I thought the fuel regulator is bad or clogged for some reason (although I only have 100 miles on the car after the engine swap). I changed the corvette style regulator/filter. Now the car is a little better but still it takes 2-3 try to get it running. Any idea? Idle control? Throttle position?
I have say that before I changed the fuel pressure regulator, the engine made a popping noise while thing to start, like a carburetor back fire.
Thanks for the help.
I have say that before I changed the fuel pressure regulator, the engine made a popping noise while thing to start, like a carburetor back fire.
Thanks for the help.
Spec is 48-52 PSI on a return style with vacuum pressure regulator. This is running at Idle.
If you can't make close to 50 PSI It will have a hard time starting. The pop you heard, Is a lean pop up through the intake.
Last edited by 1FastBrick; Jun 4, 2019 at 12:52 AM.
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Thread Starter
Staging Lane
Joined: Jun 2017
Posts: 56
Likes: 5
Problem solved. This was my issue just in case somebody else runs to the similar problem.
When I changed the fuel pump after the first one died, I guess the in tank black hose which connects the pump to the fitting outside the tank, was cracked therefore the fuel was squirting badly when the pump was running. First, due to leakage, it was not creating enough pressure and then after few tries pump was able to just supply 20-25 PSI to fuel rail since most of fuel was squirting out at the cracked hose connection. I took the pump out and put it in a bucket of gas (per tanksins tech support) and I was able to isolate the issue.
By the way, Tanksinc customer service is the best.
Thanks for all the help here.
When I changed the fuel pump after the first one died, I guess the in tank black hose which connects the pump to the fitting outside the tank, was cracked therefore the fuel was squirting badly when the pump was running. First, due to leakage, it was not creating enough pressure and then after few tries pump was able to just supply 20-25 PSI to fuel rail since most of fuel was squirting out at the cracked hose connection. I took the pump out and put it in a bucket of gas (per tanksins tech support) and I was able to isolate the issue.
By the way, Tanksinc customer service is the best.
Thanks for all the help here.
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