Cold Start fine but Warmed up it struggles. Vapor lock or CPS?

Hey everyone. I have an 05 Liberty 3.7. Cold starts are fine but anything after that it struggles to turn over and run. Wait about 30 minutes to an hour and its fine starting again. I replaced spark plugs and the coils are fine, also cleaned the throttle body but no luck. I took the OEM fuel pump out to give it a look, it was completely dirty and looks clogged so my mind went to fuel issues/vapor lock. I ordered a new one but now I'm seeing some people say it could be the camshaft position sensor. I doubt its that given the state of the fuel pump and when it does start after cooling down it struggles to rev like its not receiving fuel for about 30 seconds then it runs fine. Just wanted to get your guys' opinions but I'm almost sure that its the fuel pump since its like what 21 years old by now... thanks for any responses

No check engine light? No codes?

I had an 89 Mustang that did exactly what you're describing and it turned out to be a bad fuel pump so you may be on the right track. If it's as gross as you describe it sounds like you'll want to replace it anyway. I don't know if and where a fuel filter might be on a 05 but if you have one be sure to replace it at the same time. The in-tank strainer looks like it will do a pretty thorough job of filtration and hopefully that comes with your new pump.

Shankster said:

No check engine light? No codes?

I had an 89 Mustang that did exactly what you're describing and it turned out to be a bad fuel pump so you may be on the right track. If it's as gross as you describe it sounds like you'll want to replace it anyway. I don't know if and where a fuel filter might be on a 05 but if you have one be sure to replace it at the same time. The in-tank strainer looks like it will do a pretty thorough job of filtration and hopefully that comes with your new pump.

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Hey thanks for the response. It only has a code for the transmission so its probably the dirty fuel pump/filter and since the 05 model doesnt have a replaceable filter I gotta replace the entire unit. Nice wheel setup btw, i miss my beefy off road tires

I had same issue! Now when warm I put key in and wait the few seconds for the dash lights to go out. This was from another member. Works great and no warm hard starts. May be an issue with detecting the key? However try that.

The Crank position sensor is often the problem if hard starting warm. I suppose since the cam sensor is similar in construction it could be that as well, but my experience is usually the Crank Position sensor. Just do both since they are cheap and easy to change.

tonyiiiafl said:

I had same issue! Now when warm I put key in and wait the few seconds for the dash lights to go out. This was from another member. Works great and no warm hard starts. May be an issue with detecting the key? However try that.

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I'll have to try that too. Since the issue doesn't happen every time when warm, but never when cold, I just give it some gas now when starting it warm and that seems to help. When it does happen, feathering the gas when starting again sometimes helps.

DavidG91 said:

I'll have to try that too. Since the issue doesn't happen every time when warm, but never when cold, I just give it some gas now when starting it warm and that seems to help. When it does happen, feathering the gas when starting again sometimes helps.

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Let us know how that works

this sounds similar to my problem.
Go to start the jeep after driving someplace and letting it sit for a bit, and it sputters and coughs and eventually dies. Cycle the key and it starts right up.
My gut feeling is, something to do with the fuel pressure regulator or fuel pump. But it doesn't do it all the time, and it doesn't do it when cold starting for the first time on a given day. Hard to gather accurate data about fuel pressure or priming as there's no service port on the rail. I've tried to test the theory where I wait until I stop hearing the fuel pump and then crank it. There seems to be no issue starting it when I do that, which to me lends credence to it being a fuel pump/pressure regulation problem, but it's an imperfect test/diagnosis.
I've also gotten reports and seen that, the 06 I recently sold is also doing the same thing.

If anyone knows how I can install a mechanical fuel pressure gauge on the rail, let me know.