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Chugging Under Load

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Old 03-21-2012, 09:53 PM
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Originally Posted by MikeGyver
Check the fuel pressure while it is chugging. Hook up a gauge and duct tape it to the outside of your windshield.


Key on, engine off, you should have +- 62 psi. Your idle sounds about right. The pressure should fluctuate with engine vacuum like yours does. More vacuum, less fuel pressure. WOT under load, there is little or no vacuum, pressure goes all the way up to reference pressure, or 62 psi.
Old 03-21-2012, 11:14 PM
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I let me buddy talk me in to changing out the crank sensor tonight and that did nothing.

The pressure hose on my gauge is not long enough to tape to windshield. Maybe I'll take the hood off and secure it to the intake mani and watch it there?

If I'm at 52psi key on engine off and not 62 like you said, wouldn't that be a FPR issue? It's the only part that hasn't been replaced. Thanks for your help.
Old 03-22-2012, 10:24 AM
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Could be a cracked spark plug. It says you also changed them at same time.

Cracked spark plug can definitely cause an intermittent miss, and surely a low rpm/high load miss...with no codes.
Old 03-22-2012, 12:14 PM
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Originally Posted by madmaro00
I let me buddy talk me in to changing out the crank sensor tonight and that did nothing.

The pressure hose on my gauge is not long enough to tape to windshield. Maybe I'll take the hood off and secure it to the intake mani and watch it there?

If I'm at 52psi key on engine off and not 62 like you said, wouldn't that be a FPR issue? It's the only part that hasn't been replaced. Thanks for your help.
Don't you have a buddy that would ride on the engine and read the guage for a couple of beers? I don't know about 52 psi, but if you could pinch a flexible part of the return line and the pressure zooms, that would indicate that the pump is OK.
Old 03-22-2012, 12:19 PM
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Originally Posted by rel3rd
Could be a cracked spark plug. It says you also changed them at same time.

Cracked spark plug can definitely cause an intermittent miss, and surely a low rpm/high load miss...with no codes.
I think you’ve hit the nail on the head with that actually. My plugs are hard to install because I have virtually no clearance between the plugs and the frame rails. I have already found one that I cracked a couple days ago. I just didn’t want to think that I could have screwed up installing spark plugs. I’m going to replace them all tonight and report back. I’m going to feel like a real douche if that’s all it is, sure it won’t be the last time.

Originally Posted by MikeGyver
Don't you have a buddy that would ride on the engine and read the guage for a couple of beers? I don't know about 52 psi, but if you could pinch a flexible part of the return line and the pressure zooms, that would indicate that the pump is OK.
I need better friends apparently, or just alcoholic ones. There is not any room to sit even remotely saftely in my shoe-horn transplant. If the plugs don't work I'll pull the hood and take her for a spin.
Old 03-23-2012, 09:26 AM
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Originally Posted by rel3rd
Could be a cracked spark plug. It says you also changed them at same time.

Cracked spark plug can definitely cause an intermittent miss, and surely a low rpm/high load miss...with no codes.
You get a gold star! Changed out my new plugs for new plugs and it's like new. Cars have a good way of making you feel dumb sometimes. Hey, at least I got to learn a bunch of new stuff and have some spare parts now.

Thanks.
Old 03-23-2012, 09:31 AM
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Originally Posted by madmaro00
You get a gold star! Changed out my new plugs for new plugs and it's like new. Cars have a good way of making you feel dumb sometimes. Hey, at least I got to learn a bunch of new stuff and have some spare parts now.

Thanks.
You're quite welcome. One thing I have learned throughout the years...when you have a new problem...always, and I mean ALWAYS, look at what you've just done...first.

Glad you got it fixed.
Old 03-23-2012, 11:45 AM
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Glad you got it fixed man.
Old 03-24-2012, 07:16 AM
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I know this is fixed. Just wanted to add, I wanted to check fuel pressure on a fiero turbo project that I was building. I secured a small video camera aimed at the gauge, then went for a ride. Came home and watched the video and all was good.
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