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87 Duke Fuel Filter or Pump? by perceptionist
Started on: 11-07-2007 01:04 PM
Replies: 4
Last post by: perceptionist on 11-07-2007 11:03 PM
perceptionist
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Report this Post11-07-2007 01:04 PM Click Here to See the Profile for perceptionistClick Here to Email perceptionistSend a Private Message to perceptionistDirect Link to This Post
I am preparing to troubleshoot if I need to replace the Fuel pump or not. I will probably just go ahead and replace the filter since it is easy and will be piece of mind.

Whenever I remove the fuel lines from my throttle body, I never get the spray of fuel I am usually warned about... No pressure is released there. This was about an hour after the engine was shut off. How long is pressure typically retained in the fuel lines after turning the engine off? I am wondering if this is an obvious indicator of a bad fuel pump?

I have yet to figure out how to go about testing fuel pressure on my car.

Engine is new (reman crate)

O2 sensor is new

Vacuum tubes all checked and replaced as needed

I have just cleaned/rebuilt the throttle body with all new gaskets and seals.

To describe the problem:

Car will start and idle barely at around 500 rpm. I will then turn in the idle stop screw in an attempt to bring the idle up to around 900 rpm but it begins to falter and dies. When I give it gas it revs fine and smooth but if I try to keep it steady at any given rpm (2k 3k) it will waver.

I just want to find out as much as I can before tackling the fuel tank removal before it is necessary.
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jetman
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Report this Post11-07-2007 01:18 PM Click Here to See the Profile for jetmanClick Here to visit jetman's HomePageClick Here to Email jetmanSend a Private Message to jetmanDirect Link to This Post
Any engine trouble codes?
First thing is to quit messing with the throttle plate adjustment screw, that's a factory set item. I would back out the screw until the plate bottoms out and then give it a half turn so the plate doesn't stick. Use of a scanner is prefered but you'll come close manually.
Double check your o-rings in the TB injector, that's a likely source of fuel leakage.
Thoroughly clean out your Idle Air Control, that may be some reason to your erratic idle.
You normally have to install a Von Schrader valve to check fuel pressure or hook up to where your fuel filter is. It's not uncommon to have a small tear in your fuel pressure regulator, it's only $15 bucks to replace the diaphragm.
After alll is said and done, disconnect the negative battery cable for a couple of minutes, this will clear the ECM and you'll have to warm up the car and drive over 35 mph to allow the ECM to relaen the idle characteristics.


------------------
jetman
Silver 86 SE 2M6 4-speed, with
"check wallet light"

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perceptionist
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Report this Post11-07-2007 01:26 PM Click Here to See the Profile for perceptionistClick Here to Email perceptionistSend a Private Message to perceptionistDirect Link to This Post
I was getting a code #35 IAC prior to the throttle body rebuild now no codes.

Injector O-rings & Fuel pressure regulator were replaced with the TB rebuild kit.

Battery was out of the car for a couple months while the engine was replaced but I have yet to take it for a drive. So the ECM will not learn while parked/idling?
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jetman
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Report this Post11-07-2007 03:39 PM Click Here to See the Profile for jetmanClick Here to visit jetman's HomePageClick Here to Email jetmanSend a Private Message to jetmanDirect Link to This Post
This works on the V-6 engines. Jump the ADL with a paperclip, just like checking codes, turn ignition to on position, after 30 seconds disconnect IAC connector, turn key off, **** disconnect ECM fuse and negative cable. Reconnect IAC connector, fuse, and then battery cable and turn ignition to the on position for 15 seconds, then turn ignition off. This will now reset the IAC to a known key-off "park" position. Now start the car, the ECM should be able to control the idle but will still need to be driven to learn some other values.
*****(Normally on V-6 engines, once you capture the IAC and disconnect connector, you'll start engine and play with plate screw to get the lowest running idle, a scanner is highly recommended.)

87 Duke engine has dis ignition, if car still doesn't run properly (within reason) you may want to pull plugs and check wires. As I have been thinking about this today, your temp senders have alot to do with how your ECM regulates the fuel mapping but you said it's a reman, should be good.
I would love to know what the fuel pressure is at. Didn't GM make it tough to check fuel pressure, no Von Schrader valve like the V-6 engines.
Maybe this will help, if not, it's another bump, maybe some other rmembers will chime in here for you.

EDIT,,, See if the auto parts store has a loaner program for fuel pressure testers, the fuel filter connections seem like the logical place to hook up to test.

[This message has been edited by jetman (edited 11-07-2007).]

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perceptionist
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Report this Post11-07-2007 11:03 PM Click Here to See the Profile for perceptionistClick Here to Email perceptionistSend a Private Message to perceptionistDirect Link to This Post
Thank you for the replies.

I just replaced the fuel filter and wow was it clogged! It still was idling up & down until I drove it up the block and now it seems to be idling pretty steady.
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