98 C5 Long Crank/ No start
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5th Gear
Joined: Nov 2020
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98 C5 Long Crank/ No start
I'll try and make this post as short as possible
my 98 c5 will long crank and not start until the second try every single time AFTER the car is driven. It will start up every time if it sits for a couple hours, but won't start up if you wait 20-30 mins. I've noticed that the fuel pump won't prime very loud unless the car is cold, im guessing something is getting hot and not allowing it to prime correctly since it primes loud and starts right up after sitting all night. I have replaced the fuel pump, battery, fuel filter, and plugs/wires. Any recommendations or thoughts on the issue? I do have lontube headers but my starter has a heat blanket and theyre wrapped.
my 98 c5 will long crank and not start until the second try every single time AFTER the car is driven. It will start up every time if it sits for a couple hours, but won't start up if you wait 20-30 mins. I've noticed that the fuel pump won't prime very loud unless the car is cold, im guessing something is getting hot and not allowing it to prime correctly since it primes loud and starts right up after sitting all night. I have replaced the fuel pump, battery, fuel filter, and plugs/wires. Any recommendations or thoughts on the issue? I do have lontube headers but my starter has a heat blanket and theyre wrapped.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,626
Likes: 4,069
From: Cape Coral, Florida
Welcome to the Forum !!...long crank times can be a failing cam sensor or maybe high resistance in your fuel pump wiring when it heats up...do you know how to perform a voltage drop test on the power and ground sides of the circuit ??...you can probably rule out fuel pressure bleeding down after shutdown since it starts OK after sitting all night...you can check the current draw on the pump too...pump draws about 6 amps or so so checking amps with a DVOM that usually limits current flow to 10 amps should be OK..,you can jump pins 87 and 30 at the pump relay using the ammeter function of your DVOM and see what you have !!
Thread Starter
5th Gear
Joined: Nov 2020
Posts: 5
Likes: 0
Welcome to the Forum !!...long crank times can be a failing cam sensor or maybe high resistance in your fuel pump wiring when it heats up...do you know how to perform a voltage drop test on the power and ground sides of the circuit ??...you can probably rule out fuel pressure bleeding down after shutdown since it starts OK after sitting all night...you can check the current draw on the pump too...pump draws about 6 amps or so so checking amps with a DVOM that usually limits current flow to 10 amps should be OK..,you can jump pins 87 and 30 at the pump relay using the ammeter function of your DVOM and see what you have !!
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,626
Likes: 4,069
From: Cape Coral, Florida
I hooked up a fuel pressure gauge to my rail and the pressure drops steadily to 0 as soon as I shut the car off, the injectors, fuel regulator and pump are all new. This is really confusing to me because the car will turn on first thing in the morning even though it has 0 pressure built up. Could this be the check valve in the rear?
this is how mine is set up !!
