5.0 Surging
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5.0 Surging
I've got a 1987 Mercury Grand Marquis with the 5.0 EFI engine in it. This car will be turned into a demolition derby vehicle.
So heres the deal.........I took many things out/off of the car, including the smog pump, the whole a/c unit, heater (I looped the line back into itself), all the headlight electrical from the frontof the car, and the exhaust is cut off. Also, the interior is gutted, I have moved the battery to the passenger side floor board, and the fuel tank was replaced with a boat-type tank and replaced the fuel pump with an inline fuel pump out of an 87 F-150 EFI. I did leave the dash untouched, though.
My problem right now is that the engine is surging when it idles, and when the gas pedal is pushed in fast, the engine takes a little while to catch up. Did I pull too much off or is there a vacuum line loose that could be making this happen? I plugged the few vacuum lines that I did disconnect with bolts in the end. I am at a loss so any help right now is good help.
Thanks
So heres the deal.........I took many things out/off of the car, including the smog pump, the whole a/c unit, heater (I looped the line back into itself), all the headlight electrical from the frontof the car, and the exhaust is cut off. Also, the interior is gutted, I have moved the battery to the passenger side floor board, and the fuel tank was replaced with a boat-type tank and replaced the fuel pump with an inline fuel pump out of an 87 F-150 EFI. I did leave the dash untouched, though.
My problem right now is that the engine is surging when it idles, and when the gas pedal is pushed in fast, the engine takes a little while to catch up. Did I pull too much off or is there a vacuum line loose that could be making this happen? I plugged the few vacuum lines that I did disconnect with bolts in the end. I am at a loss so any help right now is good help.
Thanks
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From: sunny fla sometimes windy
Now using google earth and zooming in I can see it is definately that vacum hose over there to your left right next to where you left the 9/16" wrench!!! Clean your IAC it should clear up the idle. You better strap the heck out of that gas tank!!
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wow, you were right. It was right next to the 9/16" wrench.
Nope, not really. I'll try cleaning that when I get a chance to work on it again. And by the way, the gas tank has two 3" metal straps bolted through the floor, so I dont think it will go anywhere.
Nope, not really. I'll try cleaning that when I get a chance to work on it again. And by the way, the gas tank has two 3" metal straps bolted through the floor, so I dont think it will go anywhere.
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I cleaned the IAC (air bypass valve) along with the pcv valve and it works great now. I just has a slight hesitation when tromping on the pedal real quick. Its nowhere near as bad as before but it is noticible. What could that be from?
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From: sunny fla sometimes windy
All fuel injection will hesitate for most drivers they will not notice it but if you do any fast driving it becomes evident!! Turn up the hard throttle stop screw, it will be harder to start since the fuel injection will think you are stepping on the gas while starting, But since you are going to thrash it anyways turning it up so it idles at around 900 should lead to better accelleration off the line, plus if you get hit hard and it messes with the computer system it might stay running!! You did cut out the inertia switch and wire in a toggle switch in it's place? If not the first hit will throw it!! and you'll be dead in the water!!
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I did cut out the inertia switch but didnt put a toggle switch in its place. I guess that wouldnt be such a bad idea either, in case the line breaks. I also have the idle turned up quite a bit and it still hesitates some. Its not too big of a deal though. I think I could live with this.
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From: sunny fla sometimes windy
Yeah it is a safety item and at least if it is spraying out and hooting a flame you could cut it off!! Also I would take all the igniton wires and put them on toggles in case the steering get's pushed up it won't rip the wires and cut them, leaving you stranded!! Just put them on the dash and a big red sign that says fuel cut off for the inertia line!! Could save your life!!
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From: Louisville,Ky.
What type of pump did you put on the frame? The stock type pump needs a low pressure pusher pump in the tank to properly feed it. I'd say check your fuel pressure. It should be at least 30psi and 38 to 40 at WOT.
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I didnt actually put the pump on the frame in the grand marquis. I took the high pressure fuel pump off of an 87 f-150, which was on the frame in the truck. I didnt, however, take the low pressure pump that supplies the high pressure pump. It seems to be working fine now other than the fact that it has a little hesitation when the pedal is pushed real fast.
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