1996 L31 hard to start when cold

[east302]

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.

Question...

How would you test to see if the regulator versus the injectors were leaking?

Say that it fails a pressure test, builds to 60-psi or so but then drops off quickly when turned off. Do you then block the line downstream of the regulator and see if pressure still drops - meaning it is leaking through injectors? But, with it still blocked off, if it builds pressure and holds, does that mean that it is the regulator that isn’t holding?


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[Supercharged111]

Could pop the plenum off and see if there's a clean streak on the plenum floor near the vacuum nipple for the FPR. Or drop a scope in through the throttle body to see.

 

[Oldblue98]

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?

You already have it, nothing to lose but labor unless you need to return it or need the cash. I would not want to make that call for you because fuel pumps are not easy or cheap to change. But if I already had it I would probably start there. If you have to change pumps do not choose your pump by price, some of those cheap pumps are garbage.. People here seem to swear by the ac delco pumps or the delphi brand, at the time I changed mine I tossed it around and read reviews and people were having good luck with bosch pumps and that is what I installed and it has been in there for 7 years at the time bosch pumps were around 300.00 but I think they are cheaper now. If and when I do it again I will more than likely go with ac delco or delphi. I lived with the prime issue until mine went bad, I would turn the key on until I heard pump stop and then start it, otherwise you had to grind on it a bit before it started. I was backing out of the driveway one day and the pump puked out in the driveway, at least it saved me money on a tow bill by puking at home lol.

 

[Greg Mck]

I changed the fuel pressure regulator and now still won’t start. I have a gauge on the manifold with 58-60 at the manifold idk maybe spark instead of fuel? I’m at a loss.

 

[east302]

It’ll be fuel, spark or air, so might as well check for spark on all eight. Get a tester that lets you see the spark (and gauge its quality) versus the ones that just trip a light bulb.

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[Greg Mck]

Just to close this issue for me and for everyone else who was following.
After replacing the fuel pressure regulator it still didn’t start. I also replaced the ignition coil and module. Cap and rotor and the pick up in the distributor. And tried at least one old crank position sensor. None of this worked. So I brought it to a mechanic who said it the spider. Then he was like I don’t fix that. Older gentleman he said his back limited him. So then I brought it to another mechanic who finally fixed the problem. After all that it was the crank position sensor that was bad. go figure. He said” don’t buy electronics from auto zone because it’s hit and miss.” So won’t be using them for any kind of sensors anymore.

 

[94burbk1500]

Just to close this issue for me and for everyone else who was following.
After replacing the fuel pressure regulator it still didn’t start. I also replaced the ignition coil and module. Cap and rotor and the pick up in the distributor. And tried at least one old crank position sensor. None of this worked. So I brought it to a mechanic who said it the spider. Then he was like I don’t fix that. Older gentleman he said his back limited him. So then I brought it to another mechanic who finally fixed the problem. After all that it was the crank position sensor that was bad. go figure. He said” don’t buy electronics from auto zone because it’s hit and miss.” So won’t be using them for any kind of sensors anymore.

You can buy electronics from parts stores, just don't buy parts store brand electronics, stick to AC Delco whenever possible. Glad you got it sorted out.

 

[Oldblue98]

Just to close this issue for me and for everyone else who was following.
After replacing the fuel pressure regulator it still didn’t start. I also replaced the ignition coil and module. Cap and rotor and the pick up in the distributor. And tried at least one old crank position sensor. None of this worked. So I brought it to a mechanic who said it the spider. Then he was like I don’t fix that. Older gentleman he said his back limited him. So then I brought it to another mechanic who finally fixed the problem. After all that it was the crank position sensor that was bad. go figure. He said” don’t buy electronics from auto zone because it’s hit and miss.” So won’t be using them for any kind of sensors anymore.

At least it didn't cost you a broke starter and flex plate and transmission removal =) They are bad about causing kick back as well. Ask me how I know lol

 

[Supercharged111]

You can buy electronics from parts stores, just don't buy parts store brand electronics, stick to AC Delco whenever possible. Glad you got it sorted out.

LOL, who in their right mind would pay parts store prices for AC Delco? AC online is cheaper than Dorman is at O Reilly's. Plus they'd probably stick you for shipping as it's likely not even in their own supply chain.

 

[94burbk1500]

LOL, who in their right mind would pay parts store prices for AC Delco? AC online is cheaper than Dorman is at O Reilly's. Plus they'd probably stick you for shipping as it's likely not even in their own supply chain.

Someone who can't wait. I prefer to order on rockauto or amazon when possible, but sometimes you need a part now.