1996 L31 hard to start when cold

[Greg Mck]

On the first start of the day it doesn’t want to start. It takes extremely long cranking time start to start. Once it starts it hesitates and acts like it wants to die. But if I leave it to warm up it works fine. And will start the rest of the day no problem. And run fine. Any ideas?

 

[Oldblue98]

On the first start of the day it doesn’t want to start. It takes extremely long cranking time start to start. Once it starts it hesitates and acts like it wants to die. But if I leave it to warm up it works fine. And will start the rest of the day no problem. And run fine. Any ideas?

Have you tried turning key on and let it sit a few seconds before trying to spin it over, injectors may be losing prime or pump may be getting weak and tired. My old pump would act like that if you just hit key and started spinning engine over, it would take longer to start than if you turn key on and listen for pump to prime up and then start. Was not long before pump puked and new pump solved the issues.

 

[east302]

Check the fuel pressure and see what you have. Spec is 60-66 psi ignition on/engine off.


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[Greg Mck]

I have 60 psi upon turning the key on, and 54 at idle. Tapping the peddle it goes up to 65psi. I tried replacing the engine coolant temp sensor and maybe it helped some but turning the key and waiting for about 30-45 sec (like old blue said)and then starting seems to work best for starting for the first start. Like I said after I intital warm up it works and starts fine. Maybe the fuel pressure regulator is going bad?

 

[Oldblue98]

I have 60 psi upon turning the key on, and 54 at idle. Tapping the peddle it goes up to 65psi. I tried replacing the engine coolant temp sensor and maybe it helped some but turning the key and waiting for about 30-45 sec (like old blue said)and then starting seems to work best for starting for the first start. Like I said after I intital warm up it works and starts fine. Maybe the fuel pressure regulator is going bad?

I have 60 psi upon turning the key on, and 54 at idle. Tapping the peddle it goes up to 65psi. I tried replacing the engine coolant temp sensor and maybe it helped some but turning the key and waiting for about 30-45 sec (like old blue said)and then starting seems to work best for starting for the first start. Like I said after I intital warm up it works and starts fine. Maybe the fuel pressure regulator is going bad?

Could be the check valve bad, letting it lose prime, kind of what I thought it could be. Some vehicles it is called a fuel anti drain back valve.

 

[Greg Mck]

Where is that located?

 

[Oldblue98]

Where is that located?

I believe on GM it is in the pump, like I said it was not long after mine started doing that when the pump failed and I replaced it. I had one other vehicle that did that and it was a old Wrangler and the anti drain back valve was a separate valve from the pump.

 

[Supercharged111]

Have you tried letting it fully prime before turnig the key to start?

 

[Ken K]

The check valve is located inside the fuel pump pressure outlet. It is not spring load, only gravity allows it to seat. Over time, fine dust & dirt finds it way into the fuel tank via the gas station. I had over a hundred shops that stop fuel pump failures & returns when inspecting the strainer. Dark strainer indicate clean the tank with hot water and agitation is the fix.
Your fuel pressure regulator is the stop for fuel returning to the tank when off. Otherwise, leakage at the injectors will cause this issue. As said, the eco will power the pump for two seconds on GM's during key on, but on a return type system, that is about 18 feet of line to fill and two seconds is not enough. Try some "Techron" in the tank to clean the injectors to help them seat. Run on low tank and repeat.
In the dealer, we isolate the system and watch for leak-down thru the pump, regulator or injectors. Adaptor hoses with shut-off valve in line help us find where if any, leakage is occurring. If it injectors, then ACDelco X66-P or GM's Top Engine Cleaner is used. Caution; Do not let this 10% mixture of X66-P and fuel return to the tank, only the injectors and fuel rail.

Chevron makes "Techron" and is the main ingredient in "Top Tier" fuel but at a lower %. Warranty allows us to clean injectors once, then directs the customer to use only "Top Tier" fuels. They sell "Techron" fuel injector cleaner in almost all local parts stores. It can only help, where ever you leak down is happening. Cheapest fix also, unless the hose on your pressure regulator has gas in it.

 

[Greg Mck]

In desperation I bought a new fuel pressure regulator before I started posting here. Do y’all think it would be worth replacing just for the hell of it? Or plan on replacing the fuel pump?